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SMITHSONIAN 




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1930 \ 



OFFICE V\^^ 



MISCELLANEOUS COLLECTIONS 



VOL. 81 




:lETt WHO, BT HIS OBSERVATIONS, RESEARCHES, 



'--^ UAS .S A VA.HAB.E ^ ^ ^ J.^^....^^, ,oa ME."-SMn„SO. 



AND EXPERIMENTS, PBC 



(Publication 3063) 



CITY OF WASHINGTON 
PUBLISHED BY THh SMITHSONIAN INSTITUTION 



1930 



BALTIMORE, MD., C. S. A. 



ADVERTISEMENT 



The present series, entitled " Smithsonian Miscellaneous Collec- 
tions." is intended to embrace all the octavo publications of the 
Institution, except the Annual Report. Its scope is not limited, 
and the volumes thus far issued relate to nearly every branch of 
science. Among" these various subjects zoology. Ijibliography, geology, 
mineralogy, anthropology, and astrophysics have predominated. 

The Institution also publishes a quarto series entitled " Smith- 
sonian Contributions to Knowledge." It consists of memoirs based 
on extended original investigations, which have resulted in important 
additions to knowledge. 

C. G. Ai'.r.OT. 
Srcrctarx of tlir Sinitlisoniiin I nsliliilioii. 



(iii) 



CONTENTS 

r TiiERioT I. Mexican mosses collected by Brother Arsene 
Brouard-II. August 15, 1928. 26 pp., 9 text figs. (Publ. 

no. 2966.) 
2. Resser.'Charles E. Cambrian fossils from the Mohave Desert. 

Tulv 5, 1928. 14 PP-> 3 pis. (Publ. no. 2970.) 
^, Snodgrass, R. E. Morphology and evolution of the msect head 

and its appendages. November 20, 1928. 158 pp., 57 text 

figs. (Publ. no. 2971.) 

4 BusHNELL, David L, Jr. Drawing by Jacques Lemoyne De 

Morcrues of Saturioua, a Timucua chief in Florida, 1564. 
August 23, 1928. 9 pp., I pl., I text fig. (Publ. no. 2972.) 

5 \bbot Charles G. The relations between the Smithsonian 

Institution and the Wright brothers. September 29, 1928. 
27 pp. (Publ. no. 2977.) 

6. Aldrich, L. B. a study of body radiation. December i, 1928. 

54 pp., 9 text figs. (Publ. no. 2980.) 

7. Roberts, Frank H. H., Jr. Recent archeological developments 

in the vicinity of El Paso, Texas. January 25, 1929. 14 PP- 
5 pis.. 8 text figs. (Publ. no. 3009.) 
■ 8 Metcalf. Maynard ^I. Parasites and the aid they give m prob- 
lems of taxonomy, geographical distribution, and paleogeog- 
raphy. February 28, 1929, 36 PP-, 3 text figs. (Publ. no. 

3010.) 
9 Miller, Gerrit S., Jr. A second collection of mammals from 

caves near St. Michel, Haiti. March 30, 1929- 30 PP- 10 pis. 

(Publ. no. 3012.) 
10 McIndoo. N. E. Tropisms and sense organs of Lepidoptera. 

April 4, 1929. 59 pp., 16 text figs. (Publ. no. 3013.) 
Ti Fowle, Frederick E. Atmospheric ozone: Its relation to some 

solar and terrestrial phenomena. March 18, 1929. 27 pp., 

13 text figs. (Publ. no. 3014.) 

12. Jeanqon, T. a. Archeological investigations in the Taos Val- 
ley, New Mexico, during 1920. June 11, 1929- 29 PP- i5 P^s- 

14 text figs. (Publ. no. 3015.) 

I-,. Wetmore, Alexander. Descriptions of four new forms of 
birds from Hispaniola. May 15, 1929- 4 PP- (P"bl. no. 3021.) 

14 Collins, Henry B., Jr. Prehistoric art of the Alaskan Eskimo. 
November 14, 1929. 52 PP- 24 pis., 2 text figs. (Publ. no. 

3023.) 
15. Hall, Maurice C. Arthropods as intermediate hosts of hel- 
minths. September 25, 1929. -y pp. (Publ. no. 3024.) 

(v) 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 

VOLUME 81. NUMBER 1 



MEXICAN MOSSES COLLECTED BY 
BROTHER ARSENE BROUARD II 



BY 

I. THERIOT 

Fontaine la Mallet, France 






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j-^v 



(Publication 2966) 



CITY OF WASHINGTON 

PUBLISHED BY THE SMITHSONIAN INSTITUTION 

AUGUST 15, 1928 



J 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOLUME 81, NUMBER 1 



MEXICAN MOSSES COLLECTED BY 
BROTHER ARSENE BROUARD-II 



BY 

I. THERIOT 

Fontaine la Mallet, France 




(Publication 2966) 



CITY OF WASHINGTON 

PUBLISHED BY THE SMITHSONIAN INSTITUTION 

AUGUST 15, 1928 



Z^t Bovi) (^afttmore (prcee 

BALTIMORE, MD., U. S. A. 



MEXICAN MOSSES COLLECTED BY BROTHER 
ARSENE BROUARD— II ' 

By I. THERIOT 

FONTAINE LA MALLET, FRANCE 

In the present paper I continue my report upon the important moss 
collections made by Brother G. Arsene, which the United States Na- 
tional Museum submitted to me for study. The species here con- 
sidered belong chiefly to the families Grimmiaceae, Funariaceae, 
Bryaceae, Orthotrichaceae, Meteoriaceae, Neckeraceae, Leskeaceae, 
and Thuidiaceae. In a third paper, in preparation, I shall review the 
Pottiaceae, Amblystegiaceae, Brachytheciaceae, and Hypnaceae. 

Through the good offices of Brother Arsene, I have entered into 
correspondence with a new and zealous collector of Mexican- mosses, 
Brother Amable (F. S. C), a teacher in Mexico City. Last year I 
received from him an important collection from the " Valley of 
Mexico," a classic locality often cited in the Prodrormis of Bescherelle. 
The plants were gathered in localities whose altitudes vary from 2,100 
to 3,400 meters. Brother Amable's mosses will be included in the 
present paper and in the following one. To distinguish them from 
those of Brother Arsene's collection they are accompanied by Brother 
Amable's name. 

About two years have elapsed since the completion of the first paper, 
and meantime Mr. V. F. Brotherus has pubHshed the second edition of 
his Genera. Important modifications have taken place in the families 
and the genera, and in the known distribution of the species. The 
reader is advised that the present work follows the plan of the second 
edition, while the preceding paper was written in conformity with 
the first edition. 



^ Part I was published as Vol. 78, No. 2, Smithsonian Miscellaneous Collec- 
tions, June 15, 1926, and to this the reader is referred for a list of special 
collecting localities with altitudes. The comments and critical notes of the 
present instalment have been translated from the French by Brother Arsene. 

Smithsonian Miscellaneous Collections, Vol. 81, No. 1 



2 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

DITRICHACEAE (continuation) 
CERATODON PURPUREUS (L.) Brid. 

Valle de Mexico : Desierto {Bro. Amable). 

CERATODON STENOCARPUS Bry. Eur. 
Valle de Mexico: Desierto (Bro. Amable 1269). 

DICRANACEAE (continuation) 
AONGSTROEMIA BRITTONIAE Ther., nom. nov. 

Aongstroemia pusilla Ther. Smithsonian Misc. Coll. 78" : 2. 1926. 

I name this species after Mrs. E. G. Britton, who had the kindness 
to inform me that the name pusilla had already been used by Hampe. 

METZLERELLA LEPTOCARPA (Schimp.) Card. 

Valle de Mexico: Desierto (Bro. Amable 1254 in part). 

Mr. R. S. Williams has established (N. Amer. FI. 15: 153. 1913) 
the synonymy of this species with Dicranodontiimi costaricense 
(C. M.) R. S. Williams. I agree with him, but, following Brotherus' 
example, I maintain the species in the genus Metzlerella. Thus the 
name becomes Metzlerella costaricensis (C. M.) Broth. 

OREAS MEXICANA Ther., sp. nov. 

(Fig. I) 

Morelia: Cerro Azul (4793). 

Autoica, corticola, pusilla. Caulis vix 1-2 mm. altus. Folia sicca 
crispula, humida valde patula, lanceolato-linearia, breviter et late acu- 
minata, subobtusa, concava, canaliculata, marginibus planis, integris, 
1.7-2.5 mm. longa, 0.25-0.35 mm. lata, costa basi 40^1, dorso laevi, ante 
apicem evanescente, cellulis basilaribus hyalinis, rectangularibus, parie- 
tibus tenuibus, sequentibus quadratis vel breviter hexagonis, saepe 
transverse dilatatis, valde chlorophyllosis, tenuiter papillosis, parietibus 
tenuibus, I0/aX6-8;u. Pedicellus sicca suberectus, tortellus, humida 
superne cygnicollus, 1-2 mm. longus; capsula minuta, sicca suberecta, 
cylindrica, valde sulcata, humida subglobosa ; peristomium simplex, 
dentes (8) bigeminati, irregulares, nunc breves, e basi late triangulari 
obtusi, 6-8-trabeculati, nunc elongati, 14-16-trabeculati (0.12 mm. 
alti), longitudinaliter striati, sporae 18-24 /^ crassae. Caetera desunt 
(capsulae deoperculatae). 



NO. I 



MEXICAN MOSSES THERIOT 



This is one of the finest discoveries made by Brother Arsene. The 
genus Oreas has been regarded as monotypic ; liesides it has not been 
known in America. 




Fig. I. — Orcas me.vicana Ther. i, 2, 3, leaves; 4, acumen; 5, margin and 
median cells; 6, basal areolation; 7, cross-section of a leaf toward the middle; 
8, perigonial leaves; 9, dry capsule; 10, moist capsule; 11, 12, 13, teeth of 
peristome. 

Oreas Martiana Hoppe & Hornsch. is more robust, with stems 2 to 
6 cm. long; the leaves are very acute, partially revolute, and long- 
attenuate at the apex ; the costa is excurrent, and the cells are strongly 
incrassate and completely smooth. 



SYMBLEPHARIS HELICOPHYLLA Mont. 

Yalle de Mexico: Desierto {Bro. Amahle 1246, 1254 in part). 

In these specimens the species appears under two distinct forms, 
which are, however, rather frequently combined in the same tuft. 
They are characterized as follows : 

(a) Forma normalis. Pedicel 10 mm. long; deoperculate capsule 
2 mm. 

(b) Forma breviscta. Shorter pedicel (3-4 mm.) ; deoperculate 
capsule 1.5 mm. 

I am unable to discover any other differences between these two 
forms. 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOL. 8 1 



GRIMM I ACE AE 

COSCINODON ARSENEI Ther., sp. nov. 

(Fig. 2) 

Queretaro : Jurica, upon stones (iiooi). 

Autoicus, pusillus, sat compactus. Caulis brevis, simplex, 3-5 mm. 
altus. Folia sicca imbricata, bumida erecto-patula, obovata, breviter 
acuminata, longe pilifera, 1.5 mm. longa, i mm. lata, marginibus 
planis, integerrimis, costa valida, basi 80 /x, in pilum longum, hyalinum, 
integrum excedente, cellulis basilaribus quadratis, parce chlorophyl- 




FiG. 2. — Coscinodon Arsenci Ther. i, leaf ; 2, median cells ; 3, marginal cells ; 
4, basal areolation ; 5, capsule with calyptra ; 6, operculum ; 7, cross-section of 
calyptra; 8, teeth of peristome. 

losis, sequentibus breviter rectangularibus vel hexagonis, laevibus, 
parietibus tenuibus, majusculis, 15-30 jx longis, 12-15 /^ latis. Pedi- 
cellus erectus, circa i mm. longus ; capsula subimmersa, minuta, ovata, 
sicca laevis ; operculum conico-rostratum ; annulus latus ; peristomii 
dentes irregulares, nunc simplices, parum lacunosi, nunc fere ad basin 
fissi, papillosi, 0.35-0.40 mm. lati ; sporae 12-15 /* crassae ; calyptra 
mitraeformis, valde plicata, profunde laciniata, fere totam capsulam 
obtegens. 

Close to C. Wrightii Sull., but very distinct ; differing from it by 
the larger, entire leaves, thin-walled cells, the capsule borne upon a 
longer pedicel and consequently almost exserted, and, finally and 
chiefly, by the narrow, slightly lacunose teeth of the peristome. 



NO. I MEXICAN MOSSES THERIOT 5 

GRIMMIA OVATA Web. & Mohr, forma dioica 
Morelia: Cerro San Miguel (5070) ; Campanario (7449)- 

GRIMMIA ARSENEI Card. Rev. Bryol. 40: 37- iQ^S 

Morelia: (7894, 7906). 

Sterile plants. It would be interesting to know this plant in fruit, 
in order to be sure of its affinities. By its size and form and the 
direction and areolation of the leaves it appears very close to G. 
calif ornka Sull. ; nevertheless it may be distinguished by the areola- 
tion of the lamina, which is very opaque and formed throughout by 
two layers of cells, while in G. calif ornka the cells are bistratose only 
on the margin (i to 6 rows of cells). 

GRIMMIA CALIFORNICA Sull. 

Valle de Mexico: Salazar, upon earth {Bro. Aniable 1293). 
I believe this species is new for Mexico. 

FUNARIACEAE 
FUNARIA SARTORII C. M. 

Puebla: Hacienda Alamos (4724 in part) ; Rancho Posadas (4806). 
Distrito Federal: Mixcoac (9472); Desierto (Bro. Amahle 1206, 
1217). 

Determined from description. Brother Amable's specimens differ 
from Brother Arsene's in having shorter and slightly broader leaves, 
shorter peristome, and larger and more verrucose spores. They may 
represent a distinct species. 

FUNARIA APICULATIPILOSA Card. Rev. Bryol. 40: 37- 1913 
Puebla: Cerro Guadalupe (686, 687, 4613) ; Rancho Guadalupe 

(4590» 4592) • 

Nos. 686 and 687 have horizontal, larger capsules and a higher peri- 
stome; moreover, their leaves are more difficult to moisten. 

FUNARIA EPIPEDOSTEGIA Card. Rev. Bryol. 36: 109. 1909 
Morelia: Cerro San Miguel (5043, 5044, 5083); Campanario 
(7939a)- 

FUNARIA ORTHOPODA Ther., sp. nov. 

(Fig. 3) 
Puebla: Rio San Francisco (919, 923). 

Caulis brevissimus, 1-2 mm. altus, inferne denudatus, superne 
comosus. Folia sicca et humida erecta, difficile emollita, valde concava. 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOL. 8 1 



oblongo-acuminata, acuta, elimbata, marginibus planis, integris, 2 mm. 
longa, 0.7 mm. lata, costa tenui, percurrente ; rete pellucido, cellulis 
vesiculosis, quadratis vel breviter hexagonis, superioribus longioribus. 
Pedicellus erectus, 15-25 mm. longus, capsula inclinata, oblonga, 
arcuata, asymmetrica, macrostoma, collo brevi attenuata, profunde 
sulcata ; operculum plano-convexum ; peristomium duplex, dentes 
papillosi, baud striati, 0.5 mm. alti, processus papillosi ; sporae sub- 
laeves, 20-24 jx crassae. 




Fig. 3. — Funaria orthopoda Ther. i, 2. 3, leaves; 4, apical cells; 5, basal 
areolation ; 6, capsule ; 7, fragment of peristome. 

Belonging to the group of F. hygromctrica (L.) Sibth. Distin- 
guished from that species and its numerous forms or subspecies by a 
straight not hygroscopic pedicel, a suberect capsule, and larger spores. 

FUNARIA HYGROMETRICA (L.) Sibth. and var. CALVESCENS 
(Schwaegr.) Bry. Eur. 

Apparently very common in Mexico, as elsewhere. There are more 
than 25 numbers in the collection. I think it useless to enumerate them. 



FUNARIA CONVOLUTA Hampe 

Puebla: (7958). Morelia : Loma del Zapote (4638, 4639) ; Bosque 
San Pedro (4576). 

The species is surely close to F. hygromctrica var calvescens; never- 
theless it may be recognized by the form of the capsule, the large size 



NO. 1 MEXICAN MOSSES THERIOT 7 

of the spores, and, chiefly, by the perichaetium, the external leaves 
of which are spreading and the internal ones closely clasping the 
pedicel, all of them very concave, very shortly acuminate or sub- 
rounded, and acute or subobtuse. 
A novelty for Mexico. 

FUNARIA ANNULATA Besch. Prodr. Bryol. Mex. 48. 1871 

Puebla: Road to Cholula (713)- 

Brotherus considers this moss very close to F. cdvescens Schwaegr. 
I do not deny it, but I have not been able to examine enough speci- 
mens to appreciate the extent of the variations and to form a concrete 
opinion of its relative position. 

BRYACEAE 
WEBERA SPECTABILIS (C. M.) Jaeg. 

Bryum spcctabilc C. M. Syn. 2 : 583. 185 1. 
Morelia. Campanario (4772> 7535)- 

WEBERA CYLINDRICA Schimp. in Besch. Prodr. Bryol. Mex. 52. 1871 
Morelia: Campanario (7549. 7932, 7952); Loma Santa Maria 
(5102). 

I consider these two species very close. It would not be difficult, 
I think, to find some day transitional forms which will throw W. 
cylindrica into synonymy. Meanwhile I distinguish W. cylindrica by 
its broader leaves (0.5-0.7 mm., instead of 0.3-0.4 mm.), more fre- 
quently revolute, with a stronger costa (70-120 /x against 40-60 ix.) . 

WEBERA DIDYMODONTIA (Mitt.) Broth, in Engl. & Prantl, Pflanzenfam. 

ed. 2, i: 362. 1924 
Bryum didymodontium Mitt. Muse. Austr. Amer. 289. 1869. 

Morelia: Campanario (7547, 7555> 7556, 7640). 

Determination doubtful. In the sterile state it seems to me mipos- 
sible to distinguish with certainty this species from W. commutata 
Schimp. Only a single specimen (7556) is in fruit, and the capsules 
are very young. I recognized the species by the length of the pedicels 
(up to 4 cm.), and I give the same name to the sterile specimens 
because they are from the same place and look identical with no. 7556. 

WEBERA ZACATECANA (R. S. Williams) Ther., comb. nov. 

Pohlia sacatecana R. S. Williams, Bryologist 26 : 22,- pl- 4- I923- 
Morelia: Andameo (4833)- 



8 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

MNIOBRYUM ALBICANS (Wahlenb.) Limpr. Laubm. Deutschl. 2: 277. 1895 
Mnium albicans Wahlenb. Fl. Lapp. 353. 1812. 

Puebla: Rio San Francisco (5005). Morelia: Rincon (9436). 
Distrito Federal : Tlalpam (9500). 

EPIPTERYGIUM MEXICANUM (Besch.) Broth. 

Valle de Mexico: Desierto {Bro. Amabic). Growing as isolated 
stems among other mosses. 

BRACHYMENIUM BARBAE-MONTIS C. M. 

Puebla: Tepoxiichitl (s. n.). Morelia: Andameo (4820). Tlax- 
cala: Acuitlalpilco (743 in part). 

The last number differs from the others by its broader leaves, 
revolute for a longer distance, with a short apiculus. It is perhaps 
more than a form, but unfortunately the specimens are absolutely 
sterile. 

BRACHYMENIUM EXIGUUM Card. Rev. Bryol. 38: 7. 191 1 

Puebla: San Antonio (Bro. Nicolas 6028); Cerro Guadalupe 
(660). 

BRACHYMENIUM MURALE Schimp. in Besch. Prodr. Bryol. Max. 51. 1871 

Puebla: Rancho Posadas (4804). Veracruz: Cordoba (s. n.). 

BRACHYMENIUM Sect. LEPTOSTOMOPSIS 

I recognized in this section among Brother Arsene's mosses the 
following species: B. capiUare Schimp., B. lutcolimt (C. M.) Jaeg., 
B. imbricatum Schimp., B. Munchii Broth., B. clilorocarpum Card., 
B. Lozanoi Card., B. iiivcitiii Besch., and B. condensafum R. S. 
Williams. 

Among these numerous species, the last three are easy to distin- 
guish : B. Lozanoi by its leaves distinctly and finely serrate near the 
apex ; B. nivcuni and B. condensafum by their leaves widely marginate 
and finely dentate at the apex. 

It is not the same for the others. The determination of the numer- 
ous specimens has been a laborious and delicate task, because, accord- 
ing to my observations, among the characters attributed to each one 
of these species few are constant. And yet I had before me, for 
every one of them, a fragment of the type or of some other plant 



NO, I MEXICAN MOSSES — THERIOT 9 

authentically named! But where a variable species is concerned, a 
single stem can not give an accurate and complete idea. This stem 
constitutes simply a form of the species, and its comparison with the 
others makes them appear, very often, as if they were distinct species. 
Such are the reasons why my opinion about these debatable species 
is founded more on the mosses I had to identify than upon the small 
fragmentary authentic specimens at hand ; hence it seems useful to 
say how I understand them. 

BRACHYMENIUM CAPILLARE Schimp. in Besch. Prodr. Bryol. Mex. 50. 1871 

Innovations not julaceous, rather laxly foliated; leaves oblong, 
obtuse, the margins plane or almost plane, the costa excurrent ; stem 
and perichaetial leaves obtuse-lanceolate, strongly revolute. Capsule 
cylindrical. 

Puebla: Esperanza (4508, 4659- 4668, 4669, 4682, 4992). Morelia: 
Campanario (7461, 7463). 

No. 4992 is a form with larger leaves, and nos. 7461 and 7463 a 
form with a thicker capsule. 

BRACHYMENIUM LUTEOLUM (C. M.) Jaeg. 
Bryum iutcolmn C. M. Linnaea 38 : 625. 1874. 

Close to the preceding species. Differs by julaceous innovations 
with densely imbricate leaves, which are oval-suborbicular. 

Puebla: Hacienda Batan (s. n.). MoreHa : Bosque San Pedro 

(4579) • 

BRACHYMENIUM IMBRICATUM Schimp. 
Bryum imbricatifolium C. M. Syn. 2 : 578. 1851. 

As in S. luteolum, with julaceous innovations ; leaves strongly im- 
bricate, but in both the stem and branch leaves the costa almost always 
disappearing below the apex. 

Puebla: Hacienda Alamos (4718, 47^1, 4759^ 4865). 

BRACHYMENIUM MUNCHII Broth, in Card. Rev. Bryol. 38: 5- i9" 

Julaceous innovations with oval or oblong leaves, narrower at the 
apex and almost acute. The stem and perichaetial leaves are subobtuse 
or acute, with a strong (60 /a) costa always excurrent. 

Puebla: Esperanza (4943); Mahnche (6004); Hacienda Batan 
(4973)- 



lO SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

Judging by the exsiccatae I possess (Bryoth. Levier, leg. Miinch; 
Pringle 15078), this species is very variable. The leaves of the inno- 
vations are more or less elongate and somewhat narrow-acute ; the 
perichaetial leaves are more or less revolute, widened or not at the 
base ; the capsule is oblong, but in Brother Arsene's specimens it is 
more often claviform. 

BRACHYMENIUM CHLOROCARPUM Card. Rev. Bryol. 36: in. 1909 

This possesses a special habit, which, once seen, renders easy its 
recognition. Its affinities are with B. imbricatum and B. Munchii. It 
is distinguished from both species by the costa, which is excurrent in 
the leaves of the innovations and generally evanescent in the peri- 
chaetial ones ; also " by the soft, pale, inclined or hanging capsule and 
by the strongly flexuous pedicel " (teste Cardot). 

Puebla: (4624). Morelia: Andameo (4831). 

BRACHYMENIUM LOZANOI Card. Rev. Bryol. 38: 5. 191 1 

Morelia: Cerro Azul (4558, 4560). 

Near B. systylinm (C. M.) Jaeg. by the size and the form of the 
leaves; but in B. systylinm the entire or subentire leaves are difficult 
to moisten. 

BRACHYMENIUM NIVEUM Besch. Journ. de Bot. 15: 383. 1901 
Morelia: Andameo (4834). 

BRACHYMENIUM CONDENSATUM R. S. Williams, Bryologist 
26: 2. 1923 

Morelia: Cerro San Miguel (5065). 

Very close to the preceding species. I distinguish it hy its leaves, 
with a wider margin toward the apex, a costa vanishing more often 
below the apex, and a shorter and less flexuous hyaline hair point. 
In B. niveuni the hair point is very long and flexuous, giving the 
tufts the facies of some Argyrohrynm, like B. arachnoidemn for 
instance. 

BRACHYMENIUM MEXICANUM Mont. Ann. Sci. Nat. II. Bot. 9: 54. 1838 

Morelia: (7905) ; Cerro San Miguel (4871, 4874, 5061). 

The leaves are exactly entire. That condition agrees well with 
Montague's original description, " foliis integerrimis," and with C. 
Muller's. Mitten saw them difl:'erently : " Margine superne minute 
serrulata ; " it was probably an exceptional case. 



NO. I MEXICAN MOSSES — THERIOT II 

ANOMOBRYUM FILIFORME (Dicks.) Husn. var. MEXICANUM (Schimp.) 
Par. Ind. Bryol. 182. 1894 

Puebla: Hacienda Alamos (577, 4636). Morelia: (7889, 7902, 
7911); Andameo (4821, 4836); Campanario (7445. 75i3. 7548). 
Valle de Mexico: Desierto {Bra. Amable). 

ANOMOBRYUM PLICATUM Card. Rev. Bryol. 36: 112. 1909 
Morelia: Wall of a garden (7966), 

BRYUM LAXULUM Card. Rev. Bryol. 36: 113. 1909 

Morelia: (7647, 7648, 7649, 7650, 7655, 7949) ; Jesus del Monte 
(7609) ; Bosque San Pedro (4585) ; Loma Santa Maria (7865, 7878, 
7881, 7883). Valle de Mexico: Desierto {Bro. Amable). 

Some of these collections, chiefly nos. 7647, 7649, and 7650, have 
elongate and narrow leaves like B. lanceolifolium Card. ; but the 
cuspid, the reflection of the edges, and the areolation are characters 
which connect them closely to B. laxuhim. 

BRYUM Sect. ARGYROBRYUM 

The species of this section belonging to Brother Arsene's collection 
are cited or described in the first paper. 

BRYUM ARGENTEUM L. 

Valle de Mexico: Portales {Bro. Amable 1258). 
A form tending toward var. brachycarpum Card. 

BRYUM ARGENTEUM L. var. COSTARICENSE Rev. & Card. 

Valle de Mexico: Salazar (Bro. Amable 1310) ; Colhuacan (1319). 

BRYUM ARGENTEUM L. var. CHLOROCARPUM Card. 

Valle de Mexico: Desierto (Bro. Amable 1266) ; Contadero (1297 
in part). 

This is a very curious plant. The capsule, narrowly cyHndrical and 
attenuate into a long neck, would make one believe it a good species if 
one did not find in the same cluster shorter capsules of a different 
outline, among which some insensibly approach the typical form of 
B. argenteiim. 

BRYUM LIEBMANNIANUM C. M. Syn. 2: 573. 1851 
Mexico: Upon a roof {Bro. Amable). 



12 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 



BRYUM SQUARRULOSUM (Card.) Ther. 

Brachymenhim sqnarrulosum Card. Rev. Bryol. 38:7, 31. 1911. 

(Fig. 4) 

I have this moss under two different names in my collections : 
Brachyineniuin squarrulosum Card., Barnes & Land 486, Pringle 
10580 in part, 15213; Bryum suhchryscum Broth. & Par. in sched. 
(comm. Paris), Bro. Arsene. Although these names belong to differ- 
ent genera, the two plants are certainly identical. 

I found this same species, abundantly and well fruited, in Brother 
Arsene's collection ( see below) . The capsules have an inner peristome 
made up of a basal membrane half the height of the teeth, the seg- 




FiG. 4. — Bryum squarrulosum (Card.) Ther. i, 2, 3, stem leaves; 4, peri- 
chaetial leaf ; 5, leaf from the innovation ; 6, median cells ; 7, marginal cells ; 
8, basal areolation ; 9, moist capsule. 

ments widely split, oblong-lanceolate, equal to the teeth and provided 
with appendiculate cilia. The peristome of Barnes & Land 486 is in 
every way similar. This moss, which has the habit, leaves, and areola- 
tion of a Brachymeniiiin, belongs, then, by its capsule, to the genus 
Bryum. It has a close affinity with Bryum chryseum Mitt., the same 
facies, size, and leaves. But the two species are essentially different 
in their sporophyte: B. squarrulosum has a short, thick, claviform 
capsule, and B. chryseum has an elongate, narrow capsule insensibly 
attenuate into a neck of the same length. 

The name proposed by Brotherus and Paris was happily chosen, 
but it remains a nomcn nudum; the one given by Cardot is the 
valid one. 



NO. I MEXICAN MOSSES — THERIOT I3 

Morelia: Loma del Zapote (7506) ; Andameo (4818, 4846) ; 
Punguato (4879, 5059) ; Campanario (7559) ; Jesus del Monte 
(7619). Distrito Federal : Mixcoac (9151, 9457). Tlaxcala: Acuit- 
lalpilco (718). 

No. 4846 presents a curious and rare mixture of two species, Bryum 
squarrulosum and Erythrodontimn densuni var. brevifolium Card., 
which have the same size, same habit, and same shade of color, and 
are indistinguishable to the untrained eye. 

BRYUM MICROBALANUM Card. Rev. Bryol. 36: 112. 1909 
Puebla: Rancho Posadas (4809). 

BRYUM ROSULATUM C. M. Hot. Zeit. 14: 416. 1856 
Morelia: Campanario (7529) ; Jesus del Monte (7963 in part). 

BRYUM LATILIMBATUM Card. Rev. Bryol. 36: 114. 1909 
Puebla: Cerro Guadalupe (794). 

BRYUM EHRENBERGIANUM C. M. Syn. i: 255. 1849 

Puebla: (4991); Esperanza (4941). Tlaxcala: (606 in part). 
Valle de Mexico: Desierto (Bro. Ainablc 1208). 

BRYUM COMATUM Besch. Prodr. Bryol. Mex. 55. 1871 

Morelia: Cerro San Miguel (5084) ; Punguato (5049); Campa- 
nario (7552 in part) ; Jesus del Monte (7607) Loma Santa Maria 
(7645). Valle de Mexico : Contadero (Bro. Amable 1312). 

BRYUM ANDICOLA Hook., forma 

Puebla: Cerro Guadalupe (688). Morelia: Loma del Zapote, 
(7503); Calzada de Mexico (7630a). Distrito Federal: Mixcoac 
(9452, 9463) ; Valle de Mexico, Desierto (Bro. Amable 1203). 

Looser areolation ; cells 40-50 /a X 20 /a. 

BRYUM BOURGEANUM Card. Rev. Bryol. 36: 115. 1909 
Valle de Mexico: San Rafael (Bro. Amable 1278). 

BRYUM SUBELIMBATUM Ther., sp. nov. 

(Fig. 5) 

Puebla: Fort Lorette, alt. 2,200 m. (657). 

Caulis 2 cm. altus, laxe sed regulariter foliosus, interdum rosulatus. 
Folia sicca crispulo-contorta, elliptico-oblonga, breviter acuminata, 



14 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 



acuta, cuspidata, marginibus usque ad medium folii anguste revolutis, 
superne denticulatis, costa basi 120 /x lata, sensim attenuata, in cus- 
pidem brevem excurrente, cellulis mediis hexagonis, 50-60 fx longis, 
20-24 /ji latis, parietibus tenuibus, basilaribus breviter rectangularibus, 
marginalibus (e 2-3-ser.) linearibus, concoloribus, baud incrassatis, 
limbum vix distinctum efformantibus. Caetera desunt. 

In its size and tbe dimensions of the leaves this is to be compared 
with B. andicola Hook. ; it may be distinguished from that species by 
the more acute-acuminate, longer-cuspidate leaves, the cells being 
twice as long and also wider, and above all by the hardly differentiated 




Fig. 5. — Bryuin subelimbatum Then i, leaves; 2, apical cells near point a; 
3, marginal cells toward point b ; 4, median cells at point c ; 5, basal areolation. 

border, composed toward the middle of the leaf of 2 or 3 linear cells 
with walls as thin as those of the adjacent cells and entirely disappear- 
ing toward the apex. 

ORTHOTRICHACEAE 

ZYGODON SPATULAEFOLIUS Besch. Prodr. Bryol. Mex. 43. 1871 

Valle de Mexico: Desierto (Bro. Amahle 1252). 
Mr. N. Malta considers this species identical with Z. obtusifoliiis 
Hook. 



ZYGODON OLIGODONTUS Card. Rev. Bryol. 36: 107. 1909 
Valle de Mexico : Salazar, upon a tree {Bro. Aniable 1235 in part). 



NO. I MEXICAN MOSSES THERIOT 1 5 

ORTHOTRICHUM DIAPHANUM (Gmel.) Schrad. Spic. Fl. Germ. 69. 1794 

Bryuin diaphamirn Gmel. Syst. Nat. 2 : 1335. 1791. 

\"alle de Mexico: California {Bro. Amable 1273) ; Tlalparft {Bro. 
Amahle 1236). 

ORTHOTRICHUM MALACOPHYLLUM Card. Rev. Bryol. 38: 2. 191 1 
Valle de Mexico: Contadero {Bro. Amahle 1301 in part). 

ORTHOTRICHUM PYCNOPHYLLUM Schimp. 

Puebla: Esperanza (4680) ; Hacienda Batan (4966, 4967). 
Morelia : Cerro Azul (4794, 4930) . Valle de Mexico : Salazar {Bro. 
Amahle 1295). 

Brother Amable's material is plentiful, with well-fruited specimens, 
consequently I was able to make interesting observations and more 
particularly to ascertain the wide variability of this species. For 
instance, in the same tuft some plants have immersed capsules and 
others show them more or less exserted ; sometimes the ripe capsules 
are entirely smooth and sometimes a little costate ; the segments of the 
inner peristome may be nearly entire or more or less erose ; finally, 
the leaves, when moist, are either spreading or strongly squarrose. 

It seems that the individuals with exserted capsules and squarrose 
leaves should be called O. recnrvans Schimp., and those with immersed 
capsules O. Lozanoi Card.; but both have a densely villous calyptra, 
while in 0. recurvans and O. Lozanoi the calyptra is only sparingly 
villous. 

To what conclusion do these remarks lead if not that the names 
O. pyciiopliyllum, O. recurvans, and O. Lozanoi have been created for 
forms of a very variable species and that it is desirable, as Cardot 
suggested in 1909 (Rev. Bryol. 36: 107), to reunite them under a 
single name, the one which has priority (O. pycnophyllum Schimp.) ? 

MACROMITRIUM GHIESBREGHTII Besch. Prodr. Bryol. Mex. 44. 1871 

Puebla: Boca del Monte (4685) ; Esperanza (4671, 4676, 4681, 
4687, 4688, 4756, 4801). 

Nos. 4685, 4687, and 4688 represent forms with shorter branches, 
with leaves less appressed when dry and more spreading when moist, 
and with shorter pedicels. 

I recall that Cardot (Rev. Bryol. 38: loi. 191 1) considers M. 
Ghiesbreghtii and M. Leiboldtii Hampe as mere forms or varieties 



l6 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

of M. inexicanum Mitt., but I have not had an opportunity to form 
a personal opinion on this point. 

MACROMITRIUM PYCNOPHYLLUM Card. Rev. Bryol. 36: 108. 1909; 

37: 19. 1910 

Morelia: Campanario (7568, 7635) ; Cerro Azul (4535- 4545, 4548, 
4777) ; Cascade de Coincho (4717 in part). 

Often found intermingled with the following species. Sometimes 
the association is so intimate and the stems so entangled that the 
separation of the two species is almost impossible. 

MACROMITRIUM TORTUOSUM Schimp. in Besch. Prodr. Bryol. Mex. 45. 1871 

Morelia: Cerro Azul (4557, 4777a, 4791, 4792); Cascade de 
Coincho (4712, 4717 in part) ; Campanario (7464, 7524, 7528, 7532, 
7536, 7560, 7567, 7634a, 7636, 7638). 

Determination only probable. I had the choice between M. tor- 
tuosuiii Schimp. and M. Schhnperi Jaeg. (ilf. Uexuosum Schimp.). 
Although not absolutely identical with M. tortuosum, the specimens do 
not dififer enough to be separated. On the other hand, I do not know 
M. Schimperi, and the descriptions of the two species in Bescherelle's 
Prodromus are insufficient to permit distinguishing one from the 
other. 

CRYPHAEACEAE 
CRYPHAEA ORIZABAE Schimp. in Besch. Prodr. Bryol. Mex. 70. 1871 

Veracruz: Cordoba (s. n.). 

Determined from description. I distinguish this species from C. 
filiformis (Sw.) Brid. by the leaves, which are larger and very entire 
at the apex, and have larger cells. 

CRYPHAEA APICULATA Schimp. 

Puebla: Hacienda Batan (4970). 

The leaves are entire, as described by Bescherelle, and not " sehr 
klein gezahnt," as described by Brotherus. 

CRYPHAEA ATTENUATA Schimp. in Besch. Prodr. Bryol. Mex, 72. 1871 

Morelia: Cerro Azul (4798); Valle de Mexico: Desierto {Bro. 
Amablc 1223, 1237). 



NO. I -MEXICAN MOSSES THERIOT I7 

CRYPHAEA PATENS Hornsch. var. DECURRENS (C. M.) Schimp. & Par. 

Veracruz: Jalapa (8002). Puebla : Esperanza (7921,7975). 

According to my observations this variety differs from the type by 
the form of the leaves, which are gradually and insensibly narrowed, 
by their direction when moist (less spreading than in C. patens), 
and by the perichaetial leaves, which are enervate or nearly so. 

CRYPHAEA SARTORII Schimp. in Besch. Prodr. Bryol. Mex. 72. 1871 

Puebla: Xuchitl, alt. 2,800 m. (7980). 

Cardot (Rev. I'ryol. 38: 102. 191 1) thinks it is convenient to re- 
unite this species with C. patens. I willingly adhere to his opinion, 
because the habit, the less dentate acumen, and the less incrassate areo- 
lation do not seem to be characters sufficiently important for the 
separation of C. Sartorii. 

DENDROPOGONELLA RUFESCENS (Schimp.) E. G. Britton, Bryologist 

9: 39. 1906 

Puebla: Xuchitl (7968) ; E.speranza (7955). 

LEUCODONTACEAE (Continuation) 
LEUCODON CRYPTOTHECA Hampe, Linnaea 12: 350. 1838 
\'alle de Mexico: Desierto {Bro. Amahlc 1283, 1306). 

PTEROBRYACEAE 
RENAULDIA COCHLEARIFOLIA (Hornsch.) Broth. 
MoreHa: Cerro Azul (4559a). 

PTEROBRYOPSIS MEXICANA (Schimp.) Fleisch. Hedwigia 45: 60. 1905 

Morelia : Campanario (7460) ; Cerro Azul (4501, 4503, 4977, 4982, 
7(356) ; Cerro San Miguel (5080, 5086) ; Carindapaz (7956) ; Cas- 
cade de Coincho (4716). 

Considering these specimens in the aggregate, I have observed some 
variability in the compression of the branches, the form of the leaf, the 
length of the cells and the thickening of their walls, the density of the 
chlorophyll, etc. Some of them would thus seem to show a tendency 
toward P. Pringlci Card., a species I do not know. 



l8 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

METEORIACEAE 

PILOTRICHELLA FLEXILIS (Sw.) Jaeg., forma 

P. turgescens (C. M.) Jaeg.; Neckera turgcscens C. M. Syn. 2 : 131. 1850. 

Puebla: Esperanza (4750, 4757). Morelia : Cerro Azul (4979, 
4986). Veracruz: Jalapa (7993,8003). 

PAPILLARIA APPRESSA (Hornsch.) Jaeg. 

Puebla: Xuchitl (7991). Veracruz: Cordoba (s. n.), forma /?agf^/- 
lifera. 

Mrs. E. G. Britton considers this species a synonym of P. nigrcsccns 
(Sw.) Jaeg. 

PAPILLARIA HAHNII Besch.; Ren. & Card. Bull. Soc. Roy. Bot. Belg. 

2: 127. 1899 

Puebla: Xuchitl (7997). \ eracruz : Jalapa (7999). 

PAPILLARIA DEPPEI (Hornsch.) Jaeg. 

Puebla: Boca del Monte (4689) ; Esperanza (4749, 475i). 

No. 4751 has leaves ending in a very long and very fine acumen, 
like those of P. suhidifolia Schimp., w^hich, in my opinion, should not 
be kept specifically distinct from P. Dcppei. I might add that the 
differences I have observed between P. Dcppei and P. Hahnii are not 
of great systematic importance. 

METEORIUM ILLECEBRUM (C. M.) Mitt. Muse. Austr. Amer. 437. 1869 

Neckera illecebra C. M. Syn. 2 : 137. 1850. 

Puebla: Esperanza (4724, 4728, 4733, 4746); Xuchitl (8004). 
Morelia : Santa Clara, alt. 2,000 m. (4845) ; Campanario (7526, 7531, 
7533, 7559, 757o, 7575)- Veracruz: Jalapa (7969). 

Variable in the form of the leaves, in the length of the hair point, 
and in the number of papillae (oftener i, rarely 2 or 3) to each cell 
and their development. 

METEORIUM ILLECEBRUM (C. M.) Mitt. var. TERETIFORME Card. Rev. 

Bryol. 38: 40, 191 1 

Morelia: Cascade de Coincho (471 1). 

The following numbers belong to forma gracilis: Puebla: Es- 
peranza (4514, 4662, 4691); Hacienda Batan (4962). Morelia: 
Cerro Azul (4525) ; Zamora (7964). 



NO. I 



MEXICAN MOSSES THERIOT 



19 



NECKERACEAE 

NECKERA HORNSCHUCHIANA C. M. Syn. 2: 51. 1850 
Morelia: Cerro Azul (4526). 

NECKERA CHLOROCAULIS C. M. and N. ORBIGNYANA Lor. 

I have tried to differentiate these two species, with the help of the 
descriptions and the specimens of my collections, but have had little 
success. Indeed, it is rare to find a specimen which combines all the 
characters attributed to each species. As a matter of fact, if, among 
the mosses of Brothers Arsene and Amable enumerated below, I take 
at random three plants, I cannot find two of them identical. This 
seems to mean that I have before me transitional forms linking closely 
the extremes which have received the names A^. chlorocaidis ant/ N. 
Orbignyana. It is then more convenient, beyond a doubt, to combine 
these two species under the name N. chlorocaulis C. M., which has 
priority (1851) over Lorenz's species (1864). 

Puebla: Esperanza (4744, 7977) ; Hacienda Batan (4964, 4965). 
Morelia: Cerro Azul (4559,4798). Veracruz: Jalapa (7996)- Valle 
de Mexico: Desierto {Bro. Amable 1213, 1224, 1239). 



PILOTRICHACEAE 

PILOTRICHUM MEXICANUM Ther., sp. nov. 

(Fig. 6) 

Morelia: Loma Santa Maria (4867, 4895, 7869). 
Sterile. Caulis secundarius 4-5 cm. altus, erectus, irregulariter 
ramosus, ramis inaequalibus, saepe arcuatis, plerumque simplicibus. 




Fig. 6. — Pilotrichiim mexicanum Ther. i, stem leaf; 2, branch leaf; 3, cross- 
section of leaf ; 4, apex of a stem leaf ; 5, margin of leaf. 

Folia caulis secundarii erecto-adpressa, late ovata, acuta, concava, 
longitudinaliter plicatula, 1.5 mm. longa, 0.8 mm. lata, marginibus 
inf erne revolutis, sequentibus serrulatis, dentibus acutis hyalinis, costis 



20 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 



fere parallelis, attenuatis, ad medium evanidis. rete opaco, chloro- 
phylloso, cellulis laevibus, hexagonis, parietibus tenuibus ; folia ramea 
similia sed minora. Caetera desunt. 

A curious plant, which is very different from all the species of the 
genus to which I could compare it, by the leaves dentate in the upper 
two-thirds, by its smooth obscure areolation formed by thin-walled 
cells, and by the insensibly attenuate costae not extending beyond the 
middle of the leaf. It has the habit of P. fasciailatunv C. M., but the 
leaves of the latter are of a different form ; moreover, the costa, which 
plainly contrasts with the areolation, stops abruptly, without attenua- 
tion, and projects beyond the lamina. 



HOOKERIACEAE 
CYCLODICTYON ALBICANS (Sw.) Broth. 
Hypiuim albicans Sw. Prodr. Veg. Ind. Occ. 140. 1788. 
Morelia : Campanario ( 772 1 ) . 

CYCLODICTYON ARSENEI Ther., sp. nov. 

(Fk;. 7) 

Distrito Federal: Cuajimalpa, alt. 3,100 m. (9489). 

C. albicanti (Sw.) Broth, et C. luimcctato Card, proximum, sed 
differt rete densiore, cellulis magis chlorophyllosis, praesertim limbo 
latissimo e 3-4 seriebus cellularum formato. 




Fig. 7. — Cyclodictyon Arscnci Tlier. i, 2, 3, dorsal and lateral leaves; 4, upper 
and marginal cells near point a : 5, median and marginal cells near point c. 



NO. I MEXICAN MOSSES THERIOT 21 

Neither can our species be C. Licbmanni Schimp., for in describing 
the latter the author does not speak of a border ; besides, he compares 
it with C. albicans, attributing to it more long-cuspidate and more 
strongly dentate leaves. 

FABRONIACEAE (continuation) 
FABRONIA PATENTIFOLIA Card. 

\^alle de Mexico: Texcoco, upon trees {Bro. Amahlc 1288). 

FABRONIA DENTATA Schimp. in Besch. Prodr. Bryol. Mex. 87. 1871 

Valle de Mexico : California (5ro. Aniahle 1275) ; Chapingo, upon 
tree {Bro. Amahle 1286). 

I see in this moss a species entirely independent from F. Havinervis 
C. M. It is easy to recognize by the smaller and more abruptly nar- 
rowed leaves, with almost entire margins, a slender costa scarcely 
reaching the middle, and shorter and wider cells. 

I imagine the author was alluding to the perichaetial leaves when 
he named this species " dcntata," but it will be agreed that for a moss 
whose stem and branch leaves are entire the name is rather badly 
chosen. 

FABRONIA OCTOBLEPHARIS Schwaegr. Suppl. i=: 338. pi. 99. 1816. 
(Fig. 8, in part) 

Valle de Mexico: Contadero, upon the earth {Bro. Amahlc 1301, 
1308 in part, 1316). 

An exact match for the European moss. Cardot described (Rev. 
Bryol. 37: 50. 1910) a variety amcricana of this species, but the type 
had not, till now, been indicated in Mexico. It is worth remarking 
that the moss from Contadero grows upon the ground, a rather rare 
station for species of the genus Fabronia; yet the classical habitat of 
F. octoblcpharis in Europe is precisely " earth upon walls." 

FABRONIA OCTOBLEPHARIS Schwaeg. var. MEXICANA Ther., van nov. 

(Fig. 8, in part) 

Queretaro : Jiirica, alt. 1,850 m., on rocks {Bro. Arscne iiooo 
in part). 

DitTers from both the type and var. auicricana Card, by its squatty 
habit, its shorter, numerous, more densely leafed branches ; by its 
oval and more abruptly acuminate leaves ; by the oval, shortly apicu- 



22 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOL. 



late, subentire perichaetial leaves ; and, above all, by the slightly 
elevated (o.ii mm.) peristome, with obliquely striate and punctate 
teeth. Perhaps a distinct species. 




Fig. 8. — Fabronia octoblepharis Schwaeg. var. vie.vicana Ther. i, leaves; 2, 
apical cells; 3, upper and marginal cells; 4, basal areolation ; 5, perichaetial 
leaf ; 6, moist capsule ; 7, exothecal cells ; 8, fragment of peristome ; g, apex of 
a tooth. Fabronia octoble pilaris Schwaegr. {Bro. Aniable 1316). 10, leaf; 11, 
12, perichaetial leaves ; 13, moist capsule ; 14, fragment of peristome. 

LESKEACEAE 
RHEGMATODON FILIFORMIS Schimp. in Besch. Prodr. Bryol. Mex. 87. 1871 
Morelia: Cerro Azul (4543). 



LINDBERGIA MEXICANA (Besch.) Card. Rev. Bryol. 38: 51. 191 1 

Leskea mexicana Besch. Prodr. Bryol. Mex. 89. 1871. 

This seems to be extremely common in Mexico, if one may judge 
by the following list : Puebla : (451 1 ) ; Rancho Santa Barbara (4517, 
4518, 4597, 4601, 4810) ; Hacienda Alamos (4722, 4758, 4763, 4766) ; 
Cholula (4863) ; Molino de Huexotitla (4815). Morelia: Bosque San 
Pedro (4570.4571.4573,4588). Tlaxcala: Acuitlalpilco (743,744). 
Distrito Federal : Mixcoac (9450, 9455, 9474, 9484) ; Tlalpam 
(9496). Valle de Mexico {Bro. Amahle) \ Texcoco (1285, 1289, 
1290) ; Desierto (1212) ; San Rafael (1284) ; Tlampantla (1234) ; 
El Pehon (1216). 



NO. I 



MEXICAN MOSSES THERIOT 



23 



No. 1216, from the Penon, is a robust form. No. 1234 from 
Tlampantla is another and more remarkable form. Its leaves are 
narrowed and long-acuminate as in var. acuminata Card., but by the 
size and the areolation it is connected with the normal forms. 



LINDBERGIA MEXICANA var. ACUMINATA. Card. Rev. Bryol. 37: 51. 1910 

Puebla : Hue jotzingo (4615, 4857). Valle de Mexico : San Rafael 
{Bro. Aniable 1276). 

LINDBERGIA OVATA Ther., sp. nov. 

(Fig. 9) 

Morelia: Cerro San Miguel (5078, 5079). 

Autoica. Caulis tenellus, repens, dense caespitosus, ramis erectis 
vel circinatis. Folia densa, leviter imbricata, marginibus jjlanis, inte- 




FiG. 9. — Lindhergia ovata Ther. i, stem leaf; 2, branch leaf; 3, apical cells; 
4, basal areolation ; 5, 6, perichaetial leaves ; 7, moist capsule ; 8, fragment of 
peristome. 

gerrimis, 0.8 mm. longa, 0.5-0.6 mm. lata, rete chlorophylloso, opaco, 
cellulis ovatis, laevibus, parum incrassatis, marginalibus transverse 
dilatatis, costa subaequalia circa f folii evanescente. Folia perichaetia- 
lia similia, intima vaginantia ; pedicellus erectus, i cm. longus ; capsula 
oblonga, operculum conicum, peristomii dentes papillosi, opaci, 0.3 
mm. alti, membrana pallida, vix papillosa, processus nulli ; sporae 
30-36 /u, crassae. 

Differs from L. mexlcana Besch. by the branches with less imbricate 
leaves, somewhat spreading when dry, by its oval leaves abruptly 
contracted into a short acumen, with the costa stopping much farther 



24 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

from the apex, by the larger, wider, and more convolute inner peri- 
chaetial leaves, by the more inflated oblong capsule, with a higher 
operculum, and lastly by the longer and more densely papillose teeth 
of the peristome and the spores twice larger. 

THUIDIACEAE 
HERPETINEURON TOCCOAE (Sull.) Card. Bot. Centrabl. 19': 127. 1905 
Anomodon Toccoac Sull. Muse. Bor. Amer. 58. 1856. 
Morelia: (7907); Campanario (7454, 7465); Carindapaz (7951 
in part). 

HAPLOCLADIUM MICROPHYLLUM (Sw.) Broth. 

Hypmnii iiiicrophyllnin Sw. Prodr. Veg. Ind. Occ. 142. 1788. 

Puebla: Esperanza (4675). Morelia: Jesus del Monte (7608, 
7613. 7625). Walle de ^Mexico : Desierto (Bro. Aniahlc 1241 in part, 
1245 in part). 

RAUIA SUBCATENULATA (Schimp.) Broth. 
Pscudolcskca sitlnatonilata Schimp. in Besch. Prodr. Bryol, Mex. 90. 1871. 

Morelia : Rincon (4566) ; Pare San Pedro (4580, 4586) ; Loma 
Santa Maria (4875, 4876, 4889, 4897, 4905, 4909, 4915. 4916, 5090, 
7853) ; Campanario (7456) ; Jesus del Monte (7689). 

THUIDIUM TUERCKHEIMII C. M. Bull. Herb. Boiss. 5: 219. 1897, forma 

Morelia: Loma Santa Maria (4893). 

In habit and areolation this form approaches var. angustatiim 
Card. ; but, disregarding the fact that one cannot compare the fruit 
(the plant being sterile), it differs in the dark green color of the tufts 
and in its longer rameal leaves. The apical cells of the secondary 
branch leaves are rather frequently acute. 

THUIDIUM MEXICANUM Mitt. Muse. Austr. Amer. 577. 1869 

Morelia: Cerro Azul (4552. 4553, 4984). Valle de Mexico; San 
Rafael {Bro. Aiiiablc 1277, 1279, 1281, 1282). 

This is the form named T. orthocarpuni by Bescherelle, and reunited 
by Cardot with Mitten's species. 



NO. I MEXICAN MOSSES THERIOT 25 

THUIDIUM (EUTHUIDIUM) 

The determination of the three following species, represented by 
sterile plants, is given with all reserve, especially in the case of T. 
Schlumbcrgeri. 

THUIDIUM ROBUSTUM Card. Rev. Bryol. 37: 52. 1910 

Puebla: (4944, 4955, 4958) ; Esperanza (4677). Distrito Federal: 
Cuajimalpa (9486). 

THUIDIUM MIRADORICUM Jaeg. 

Thuidiuiii tauiariscinum var. mcxicamiin Schimp. in Besch. Prodr. Bryol. 
Mex. 92. 1871. 

Morelia: Cerro Azul (4540, 4987). 

THUIDIUM SCHLUMBERGERI Schimp. in Besch. Prodr. Bryol. Mex. 92. 1871 

Puebla : (4946, 4952) ; Esperanza (4564, 4658, 4665, 4684, 4739, 
4753, 7981). Morelia: Cerro Azul (4529, 4785) ; Cerro San Miguel 
(5055, 5074, 7502, 7545) ; Campanario (7455, 7644, 7923, 7927, 7930, 
7931. 7937)- Mexico (9477)- 

ENTODONTACEAE (continuation) 
ENTODON ERYTHROPUS Mitt. var. MEXICANUS Card., forma 

Valle de Mexico: {Bro. Amable) \ San Juanico (1260, 1261) ; 
Contadero (1304, 1309). 

Pedicel short, 8 mm.; capsule elongate and narrow (4 mm. x 
0.6 mm.) . It is not var. hreviscta Card., since, according to the author, 
that is a depauperate form, and the above plants are as robust as the 
ordinary forms of the type. There is therefore no authority for 
separating them from the var. mexicanus. I consider them as a forma 
breviseta-stenocarpa. 

ENTODON ABBREVIATUS (Bry. Eur.) Jaeg. 

Valle de Mexico: {Bro. Amable); Desierto (1245); San Rafael 
(1280) ; Contadero (1302, 1305, 1308 in part). 

ERYTHRODONTIUM TERES (C. M.) Par. Ind. Bryol. ed. 2, 159. 1904 
Ncckera teres C. M. Syn. 2 : 98. 1851, in part. 
Morelia: Cerro Azul (5081) ; Campanario (7466, 76^)2,^). 



26 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

ERYTHRODONTIUM LONGISETUM (Hook.) Par. Ind. Bryol. ed. 2, 158. 1904 

Neckcra longiseta Hook. Muse. Exot. pi. 43. 1818-20. 

I refer with doubt to this species (which now inchides E. cylin- 
dricaule C. M.) no. 7530, from El Campanario. This plant has the 
pedicel plainly yellow, but the teeth of the peristome are striate as in 
the species of the division A. Should not this last character have all 
the importance which is ordinarily given to it? 

POLYTRICHACEAE (continuation) 

ATRICHUM MULLERI Schimp. var. CONTERMINUM (Card.) Ther. 

Valle de Mexico: Desierto {Bro. Amablc 1267, 1271 in part). 

POGONATUM ERICAEFOLIUM Besch. var. LOZANOI (Card.) Card. Rev. 
Bryol. 37: 6. 1910; 38: 38. 19" 

Valle de Mexico: Desierto {Bro. Amable 1272 in part). 

POGONATUM CUSPIDATUM Besch. Prodr. Bryol. Mex. 62. 1871 
Valle de Mexico: Desierto {Bro. Amable 1210, 1270). 

POLYTRICHUM JUNIPERINUM Willd. 
Valle de Mexico: Mexico {Bro. Amable 1218). 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 

VOLUME 81, NUMBER 2 



CAMBRIAN FOSSILS FROM THE 
MOHAVE DESERT 



(With T?iree Plates) 



BY 
CHARLES E. RESSER 

Associate Curator of Stratigraphic Paleontology: 
United States National Museum 




(Publication 2970) 



CITY OF WASHINGTON 

PUBLISHED BY THE SMITHSONIAN INSTITUTION 

JULY 5, 1928 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 

VOLUME 81, NUMBER 2 



CAMBRIAN FOSSILS FROM THE 
MOHAVE DESERT 



(With Three Plates) 



BY 

CHARLES E. RESSER 

Associate Curator of Stratigraphic Paleontology, 
United States National Museum 




(Publication' 29701 



CITY OF WASHINGTON 

PUBLISHED BY THE SMITHSONIAN INSTITUTION 

JULY 5, 1928 



^^t £orb (^afttmore (pttee 

BALTIMORE, MD., U. S. A. 



CAMBRIAN FOSSILS FROM THE MOHAVE DESERT 

By CHARLES E. RESSER 

associate curator of stratigraphic paleontology, uxited states 
national museum 

(With Three Plates) 

INTRODUCTION 

Twenty years ago Darton ' first announced the finding of Cambrian 
rocks in Bristol Mountain (then called Iron Mountain), near Cadiz, 
California, on the Santa Fe Railroad, about lOO miles east of Barstow, 
a locality well south of any from which Cambrian fossils had pre- 
viously been obtained. He pointed out the fact that these beds, which 
rest unconformably on an eroded granite surface, dip down the slope 
of the hills toward the east, mentioning, in his brief description of 
the section, that the few fossil fragments found both in the shale 
below the nodular blue limestone and in the limestone layers in the 
shale above it. were thought by Dr. Walcott to be possibly Middle 
Cambrian in age. A more thorough study of the region was made in 
1921 by C. W. Clark, then a student at the University of California,' 
who published a detailed description of the section, listing fossils from 
two horizons. These lists, which had also been checked by Walcott, 
included one new name among the fossils from the lower shale and 
another for the single fossil found in the upper shale. Only the 
latter was described sufficiently to preserve the name. The name, 
Wanneria ? cadizensis, proposed for the new species in the lower 
shale becomes a noinen niidiini. Clark's original collection, together 
with one obtained later under the direction of Dr. J. C. Merriam, 
is the basis for the following discussion of the contained faunas. 

]\Iy attention was called particularly to the interesting features of 
these faunas while identifying the species prior to their return to the 
University of California, the officials of which have very kindly given 
their permission for the following descriptions. The types of the 

^ Darton, N. H., Discovery of Cambrian Rocks in Southeastern California. 
Journ. Geol., Vol. 15, 1907, p. 470. 

' Clark, C. W., Lower and Middle Cambrian Formations of the Mohave 
Desert. Univ. of Calif. Publ., Dep. Geol.. Vol. 13, No. i, 1921, pp. 1-7. 

Smithsonian Miscellaneous Collections, Vol. 81, No. 2 



2 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

specifs herein described remain in the National ^Museum, and a third 
set was set to Princeton University. These fossils are interesting in 
that they constitute the most southerly and westerly occurrence of 
Cambrian beds west of the Rocky Mountains, besides being sufficiently 
well preserved to show structural features, particularly of the 
Mesonacidae which are yet but poorly and incorrectly described. 

GEOLOGICAL SECTION AND CORRELATIONS 

The section in Bristol ^Mountain, as described by Clark, may be 
summarized as follows: about 470 feet (143.3 "''■) o^ cjuartzites rest 
unconformably on an eroded granite surface. Above this lied occurs 
about 22 feet (6.7 m.) of fine-grained, arenaceous shale containing 
thin beds of sandstone. The Mesonacid fauna herein described occurs 
abundantly in the soft shale portion of this bed. Xext above is 25 feet 
(7.6 m.) of blue to black, unfossiliferous, nodular limestone. This is 
in turn overlain by 120 feet (36.6 m.) of brown or black arenaceous 
shale from which, about 12 feet {'i^.y m.) below the top. the two ^liddle 
Cambrian fossils were obtained. The Paleozoic section is terminated 
by Carboniferous limestones about 635 feet (193.5 ^''''•) thick. 

Owing" to the presence of the Mesonacidae, the three lower beds 
were referred to the Lower Cambrian, and the overlying shale to the 
Middle Cambrian. No question can be raised as to the Middle Cam- 
brian age of the fossils in the upper shale, but the final decision as 
to the Mesonacid fauna must await the results of studies now being 
made at many places in an attempt to settle the vexing question as to 
where the Lower-Middle Cambrian boundary must be drawn. 

According to our present ideas, Bristol Mountain must be in the 
seaway through which various Cambrian seas are supposed to have 
invaded the continent from the Pacific. Both faunas here described 
would appear to be more or less closely related to those in formations 
elsewhere in the southwestern United States, all of which were 
deposited in shallow seas whose exact extent and connections are 
not yet fully known. The fossils in the lower shale find their nearest 
affinities in the Prospect Mountain formation far to the northeast 
in the Eureka District, Nevada, with some relationship also apparent 
in the intervening Silver Peak District. The seas in which these older 
beds in the three regions mentioned were deposited certainly had 
Arctic connections, whereas no faunas are at present known from 
beds deposited in strictly Pacific seas. Whether the occurrence of 
older Cambrian beds in Bristol Mountain indicates Pacific connections 
must remain undetermined for the present. However, it would appear 



NO. 2 CAMBRIAN FOSSILS FROM MOHAVE DESERT RESSER 3 

rather improbable that a strictly Arctic sea, narrow as it must have 
been and on a continental mass of such low relief as then prevailed, 
should approach so near the Pacific basin and not be connected with 
it. The ^liddle Cambrian fauna of Bristol IMountain apparently 
represents that usually characterized by the trilobite Dolichomeiopus 
productiis, a fauna that is exceedingly widespread, extending from the 
southern Appalachians to Greenland and from British Columbia to 
Arizona, usually occupying a position somewhat below the middle of 
the Middle Cambrian. This fauna again is commonly regarded as 
Arctic rather than Pacific in origin. And so, while additional light is 
shed on paleogeography by the Bristol Mountain fossils, we cannot 
yet outline the exact boundaries of those early seas. 

DISCUSSION OF SOME AIESONACID GENERA 

I do not propose at this time to undertake the much needed revision 
of the ]\Iesonacidae, but shall simply deal with questions raised by 
the particular species under discussion. 

MESONACIS Walcott 1885 

Mcsonacis Walcott, 1885, Amer. Journ. Sci., 3d ser., Vol. 29, p. 328. (De- 
scribed as a new genus.) 

Mesonacis Walcott, 1910. Smithsonian Misc. Coll., Vol. 53. No. 6, p. 261. 
(General treatise on the entire family.) 

The distinctness of the genera Mesonacis and OleneUus has been 
questioned, because many species previously referred to OleneUus 
proved upon the discovery of additional specimens to have the extra 
segments posterior to the fifteenth, and hence were transferred to 
Mesonacis. Some of these transfers appear to be ill-founded since 
no account was taken of the other generic features. 

At the present stage of the study I would suggest that both 
Mesonacis and OleneUus are good genera, although there is consid- 
erable difficulty in distinguishing the cephala or even the cephalon and 
the first fifteen segments. Several dififerences may however be pointed 
out. In Mesonacis the eyes are shorter and do not reach the occipital 
ring ; also the rim around the head is narrower, particularly near the 
genal angles. The main distinction, according to my present view, 
is to be found in the character of the so-called rudimentary segments 
that occur posterior to the fifteenth, with its large spine. Unfortu- 
nately these most important anatomical features are infrequently 
preserved, even though the percentage of entire shields to cephala is 
considerably greater than in other trilobite groups. In Mesonacis all 



4 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

these segments have pleurae, as ilkistratecl in the figures of M. 
vermontana (see particularly Walcott, 1910, pi. 26). According to 
my present views, Olcncllus had such segments, perhaps fewer in 
number, but zmthoiit pleurae, i. c, without dorsal furrows. These are 
illustrated in the specimen figured by Walcott in 1910, on plate ZZ^ 
figure I, as Pacdumias transitans. It must be remembered that most 
of our ideas of Olcnellus are based not on Hall's original figures of 
O. thompsoni but on the incorrect restoration, made from a very 
poorly preserved specimen, first published by Walcott in 1886 and 
subsequently widely copied. This figure, as Walcott stated in 1910, 
( description of pi. 35, fig. i ) is incorrect in representing the anterior 
lobe of the glabella as not reaching the rim. In this respect OlencUus 
and Mcsonacis are identical. 

The peculiar habit possessed by most of the jVIesonacidae, that of 
the genal spines advancing forward, is not an individual character- 
istic, as is commonly assumed, but is specific. This is clearly indicated 
in the following specific grouping of the specimens from this locality. 
If the position of the genal spines were a matter of individuality, it 
would not be possible, as stated later in the descriptions, to assemble 
a dozen or more specimens into each of several species in which there 
is no variation in this respect. 

PAEDUMIAS Walcott, 19 10 

Pacdiiniias Walcott, 1910, Smithsonian Misc. Coll., Vol. 53, No. 6, p. 304. 
(Described as a new genus.) 

The original description of the single species referred to this genus 
in 1 910 is based mainly on the specimens from York, Pennsylvania, 
but it is clearly stated that the type locality is in X'ermont. The 
observations on which this original discussion were based were made 
on some specimens that cannot belong to the genus. The best example 
so used is the large, well preserved specimen illustrated by Walcott, 
1910, as figure i on plate 33, which I now refer to Olcncllus. Walcott 
states on page 308, " Nearly all the specimens of Pacdumias found at 
York have the typical cephalon of P. transitans, as shown on pi. 34, 
figs. 2-4. In all of these the anterior lobe of the glabella is some 
distance from the frontal rim of the head, while in typical Olcncllus 
thompsoni and Mcsonacis vermontana from Vermont the anterior lobe 
touches the frontal rim." Thus it will be seen that he had in mind 
what he calls the " elongate form " as the typical form of Pacdumias. 
Accordingly I have chosen the specimen figured on plate 34, figure i 
as the lectotype (U. S. Nat. Mus., Cat. No. 56808). 



NO. 2 CAMBRIAN FOSSILS FROM MOHAVE DESERT RESSER 5 

Pacdumias, as it is proposed to restrict it, possesses several definite 
generic characters. The glabella fails to reach the rim and is con- 
nected with it by a ridge that crosses the intervening space. The 
marginal sutures and rim are quite like the same features in Mesonads. 
All the species strictly referable to Pacdumms thus far studied 
possess intergenal spines, a feature not present in the types of 
Mesonads or OlcneUus. 

Except that intergenal spines have not been found in Nevadia, the 
cephala of that genus and Pacdumias have a number of characters in 
common. In both, the glabella does not reach the rim and is connected 
medially with it by a ridge. In both genera the glabella tends to taper 
forward, a feature that has caused the placing of a number of species 
into Callavia that do not belong there (see p. 6). 

SYNOPTICAL CHARACTERIZATION OF MESONACIS, OLENELLUS, 
PAEDUMIAS, NEVADIA, AND CALLAVIA 

The characteristics of the various genera studied in connection with 
this paper may be briefly summarized as follows : 

Mesonads. — Glabella touches the anterior rim and does not taper 
forward, but usually has more or less of an hour-glass shape. Rim 
narrow and striated. Marginal and epistomal plates separated by 
intramarginal and marginal sutures. Third thoracic segment large, 
and a strong spine occurs on the fifteenth. Rudimentary segments, 
with well developed pleurae, posterior to the fifteenth. Hypostoma 
without spines. 

Olenellus. — Glabella as in Mesonads. Rim perhaps a little wider 
and eyes somewhat longer. Thorax same as in Mesonads, to fifteenth 
segment. Rudimentary segments posterior to the fifteenth without 
definite pleurae, i. e., without dorsal furrows. 

Paedumias. — (Restricted) Glabella usually tapers forward, never 
extends forward to rim, with which it is connected by a median ridge. 
Rim, marginal and epistomal plates, and thorax to the fifteenth seg- 
ment like Mesonads and Olenellus. Intergenal spines present. Rudi- 
mentary segments posterior to the fifteenth zvifJiout pleurae, as in 
Olenellus. Hypostoma with spines on posterior margin and connected 
with the rostral or epistomal plate by a stalk, which probably causes 
the median ridge on the upper surface of the cephalon. 

Nevadia. — Cephalon most like Paedumias. Glabella fails to reach 
the rim, with which it is connected by a median ridge. Rim and 
sutures possibly the same also, but none of the specimens is well 
enough preserved to be quite certain on these points. No intergenal 



6 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

spines observed. Thorax distinct because of the loose arrangement of 
the segments. Hypostoma unknown. 

Callazna. — Glabella fails to reach the rim, but there is no median 
ridge. Rim wide but poorly defined, in fact it may be said to be 
lacking. Intergenal spines very strong. Well developed occipital and 
thoracic spines. Third thoracic pleura not enlarged. No strong spine 
on the fifteenth segment. Hypostoma without posterior spines, 
attached directly to a broad sickle-shaped plate. This plate separates 
from the cephalon along a marginal suture (intramarginal) that corre- 
sponds to the one on the inner edge of the rim in Mesonacis, and it 
is divided into two similarly shaped pieces by the true marginal suture. 
Thus both the marginal and epistomal plates are situated on the under 
side. Since the combined width of the two plates is considerable they 
bridge the space between the anterior margin and the glabella, so that 
the hypostoma needs no stalk and hence there is no median ridge on 
the top side of the cephalon. 

The other genera assigned to this family were not studied in this 
connection and will be discussed in a later revision. 

FOSSILS FROM THE LOWER SHALE 

The following six species all occur in association in a fine-grained, 
brown, somewhat calcareous shale, which is practically indistinguish- 
able from the shales in both the eastern and western United States 
that carry the same genera of trilobites. 

Since all the fossils come from one locality and occur in two beds 
only, no locality or horizon will be listed following the descriptions. 

PATERINA PROSPECTENSIS Walcott 

Plate I, figs. I, 2 

Micromitra (Paterina) prospcctcnsis Walcott, 1912, Monogr. U. S. Geol. 
Surv., No. 51, p. 352, pi. 2, fig. 4. 

The few specimens of this brachiopod from Bristol Mountain are 
somewhat larger than the individuals from the type locality in Nevada, 
but otherwise seem to agree with them in all respects. 

MESONACIS FREMONTI (Walcott), Restricted 

Plate I, figs. 3-9; plate 2, fig. 9; plate 3, fig. 8 

Olenellus fremonti Walcott (pars), 1910, Smithsonian Misc. Coll., Vol. 53, 
No. 6, p. 320, pi. 37, figs. I, 2. 

A number of species are certainly included among Walcott's speci- 
mens grouped under this specific name. The form from southern 



NO. 2 CAMBRIAN FOSSILS FROM MOHAVE DESERT RESSER J 

California here illustrated agrees in every respect with that from the 
type locality — Eureka District, Nevada (Loc. 52), to which the 
species is now restricted, and also with the Specimens from Resting 
Springs, Inyo County, California (Loc. 14L). This is the most abun- 
dant species at Bristol Mountain, being represented by more than 50 
specimens, of which only two show a portion of the thorax. The speci- 
mens vary in size from less than one cm. in width of cephalon to more 
than 12 cm., and the position of the genal spine is exactly the same 
in all. 

The illustrations show the intramarginal suture that begins on the 
posterior margin of the cephalon, crosses over the genal angle, and 
then passes forward just inside the strongly striated rim, separating 
a marginal plate from the cheeks (see p. 5). This suture, as it passes 
forward, leaves the exact inner edge of the rim and runs along on it 
becoming less well defined, but does not reach the outer margin. A 
second suture appears to be present on the margin, thus forming a 
second detachable plate that lies under the first. This second plate, 
to which the hypostoma is probably attached, should, I think, be re- 
garded as corresponding to the rostrum or epistoma of other trilobites. 
Just what the upper plate, which carries the upper half of the genal 
spines, may represent is not clear. Provisionally I shall call this plate 
the marginal plate. In some specimens the marginal plate is broken 
away (pi. i, figs. 3, 4) exposing the underlying epistoma; in others 
both plates have been lost. 

The facial suture, the position of which in the trilobites of this 
family has been a matter of much discussion, is quite clearly indicated 
in normal position posterior to and along the eyes, but its course 
anterior to them is not apparent. 

MESONACIS BRISTOLENSIS, new species 

Plate 2, figs. 5-8 

None of the illustrated forms in the various species of the 
Mesonacidae with advanced genal spines has them in the position they 
occupy in this species. This species is represented in the collections 
by about 15 specimens in all of which the spines are in the same 
position, even though the cephala vary from 2.5 cm. to more than 
4 cm. in width, indicating again that within these limits neither size 
nor age of individuals causes variation in the position of the genal 
spines. 

This species differs from M. fremonti first of all in the more ad- 
vanced position of the long, slightly curved genal spines, which gives 



I 

I 

i 



8 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

the head a trapezoidal shape, making it shorter and wider. Again the 
facial suture shows plainly posterior to the eye but does not appear in 
front of it. The glabella of M. bristolcnsis extends farther forward 
so that it apparently overhangs the rim. It dififers also from M. 
frcmonti in having a greater constriction where the dorsal furrow is 
bent inward opposite the third pair of glabellar furrows, thus giving 
the glabella somewhat of an hour-glass shape. The occipital ring 
is wider than in M. frcmonti, and the furrow, while also interrupted, 
dififers in having the shallowing inner ends turn sharply backward 
before dying out completely. The third pair of glabellar furrows also 
does this, and the two lateral portions are parallel to the two portions 
of the occipital furrow. The second pair of glabellar furrows is 
represented by a continuous line, only slightly curved back in the 
center — less than in M. fremonti. The first pair of furrows is similar 
in direction and depth in both species. 

The rim of M. bristolcnsis appears to narrow toward the center of 
the head, owing to the more forward extension of the glabella. It is 
striated as usual and the intramarginal suture running along the inner 
edge of the marginal plate is clearly marked. This suture occupies the 
usual relative position on the greatly shortened rim and across the 
genal angle. It continues sub-parallel to the posterior edge of the free 
cheek, the outer edge of which in this case occupies a vertical posi- 
tion, constituting the lateral margin of the cephalon, and terminates in 
the lower corners of the cephalon where the facial suture reaches the 
margin. 

The palpebral lobes are relatively further forward, shorter, and 
perhaps a little more curved than in M. frcmonti. 

Mcsonacis bristolcnsis has the usual striated surface, but the striae 
appear a little stronger than in the other species. 

MESONACIS INSOLENS, new species 
Plate 2, figs. 1-4 

More than 20 cephala of this species occur in the collections, and 
again none shows any variation in the point of origin and direction of 
the advanced genal spines. A poorly preserved, almost entire specimen 
indicates some of the characters of the thorax, which also will not 
fit any of the described forms with similarly advanced genal angles. 

Compared with M. bristolcnsis, the most similar species in this 
fauna, several differences beside that of the position of the genal spine 
are readily noticeable. The shape of the cephalon is normal, being 
quite like that of M. frcmonti. The posterior portion of the facial 



NO. 2 CAMBRIAN FOSSILS FROM MOHAVE DESERT RESSER 9 

suture is again well marked. The glabella is not quite so far forward, 
but is also considerably constricted in the center by the convergence 
of the dorsal furrow. The occipitar furrow marks off a relatively 
wide occipital ring by means of two straight slits which are also 
directed slightly backward. The two parts of the third pair of glabel- 
lar furrows which have a shallow connection across the glabella, are 
peculiar in the manner of deepening and turning forward at their 
outer ends into the dorsal furrow. The second and first pairs are 
as in M. bristolcnsis, as are also the eyes. 

The pleural portion of the third thoracic segment is more than 
ordinarily enlarged, even for a Mcsoiiacis. 

PAEDUMIAS NEVADENSIS (Walcott), Restricted 

Plate 3, figs. 3-7 

Callavia ? ncvadcnsis Walcott, 1910 (pars), Smithsonian Misc. Coll., Vol. 53, 
No. 6, p. 285, pi. 38, fig. 12. 

The specific name is here restricted to the incomplete specimen 
illustrated, and its congeners, cited from the type locality, Eureka 
District, Nevada (Loc. 52). The removal of this species from 
Callazna and its reference to Pacdnmias is demanded by the structure 
of the rim, as pointed out in the preceding generic discussion. 

Since the specimens from Bristol Mountain seem to agree in all 
respects so far as the incomplete Nevada specimens of P. ncvadcnsis 
permit comparison, they may be counted as representing a second 
species common to the two localities. 

Owing to the tapering anterior glabellar lobe, coupled with its dis- 
tance from the anterior margin, this species cannot well be confused 
with any other at the California locality, except its close ally P. clarki. 
Intergenal spines are present. 

PAEDUMIAS CLARKI, new species 

Plate 3, figs. I, 2 

At first this species was referred to one of the forms included in 
Mesonacis gilhcrti, but closer comparison showed differences from all 
of them. It seems certain also that some of the specimens referred 
by authors to the species Mesonacis gilbcrti belong neither to that 
species nor even to Mesonacis, but are distinct species of Paedumias. 

Compared with P. ncvadcnsis, P. clarki is immediately distinguished 
by the fuller anterior lobe of the glabella and by the shorter distance 
between that and the frontal rim. The intergenal spines in P. clarki 
are too weak to show in the photographs. 



£0 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

Unfortunately the specimen illustrated in plate 3, figure i fails to 
preserve the rear portion of the thorax so that its features cannot 
be determined. 

FAUNA OF THE UPPER SHALE 

Two species were found in the IMiddle Cambrian shale overlying 
the nodular limestone. They lie side by side on one small piece of rock. 

DOLICHOMETOPUS ? LODENSIS (Clark) 

Plate 3, fig. 9 

Bathyuriscus howelli lodensis Clark, 1921, Univ. Calif. Pub!., Dep. Geo!., 
Vol. 13, No. I, p. 6. 

The original description states simply that the thoracic segments 
number eight and that the pleurae of the fifth are much longer than 
the rest, particularly than the three succeeding ones. 

This species is referred to Dolichometopus in spite of the fact that 
no other species now in the genus has the long fifth thoracic pleurae. 
Except for this and the sharper pleural spines, this species agrees 
quite closely with the adjacent specimen referred to D. productus. 

DOLICHOMETOPUS PRODUCTUS (Hall and Whitfield) 

Plate 3, fig. 9 

Ogygia producta Hall and Whitfield. 1887, U. S. Geol. Expl. 40th Parall., 

Vol. 4, p. 244, pi. 2, figs. 31-35. 
Dolichometopus productus Walcott, 1916, Smithsonian Misc. Coll.. Vol. 64, 

No. 5, p. 369, pi. 53, figs. 2-4. 

This single incomplete specimen appears to be the same as the 
common D. productus, a widespread IMiddle Cambrian species. 



12 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 



DESCRIPTION OF PLATE P 

PAGE 

Paterina prospectcnsis (Walcott ) 6 

Fig. I. (X2.) Large dorsal valve. Plesiotype. U. S. Nat. Mus., Cat. 
No. 7^2>77- 
2. ( X 2.) Ventral and dorsal valves. Plesiotype. U. S. Nat. Mus., 
Cat. No. 78378. 

Mesonacis frcinonti (Walcott) 6 

Fig. 3. Fairly well preserved cephalon. The course of the posterior 
facial suture, the marginal suture, the occiptal and intergenal 
spines, and the general shape of the cranidium, together with 
the slightly advanced position of the genal spines, are clearly 
shown. Plesiotype. U. S. Nat. Mus., Cat. No. 78379. 

4. Another cephalon in which the anterior margin on the left is 

disturbed by the peculiar slickensiding in the fossils from 
this locality. Size and position of the eyes and character of 
glabeller furrows are well shown. Plesiotype. U. S. Nat. 
Mus.. Cat. No. 78380. 

5. A third, less complete cephalon, well preserved on the right side, 

showing particularly the posterior facial and intramarginal 
sutures as well as the striations on the rim. Plesiotype. U. S. 
Nat. Mus., Cat. No. 78381. 

6. Small cephalon with left eye practically complete. Plesiotype. 

U. S. Nat. Mus., Cat. No. 78382. 

7. Mould of portion of cephalon and thorax. Note extra width of 

third segment. Plesiotype. U. S. Nat. Mus., Cat. No. 78383. 

8. ( X 4-) Enlargement of genal angle of specimen illustrated in 

preceding figures, showing striated rim and course of the intra- 
marginal suture across the genal angle. 

9. The associated hypostoma, referred to the species. Plesiotype. 

U. S. Nat. Mus.. Cat. No. 78384- 



^ All figures natural size unless otherwise stated. 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOL. 81, NO. 2, PL. 1 






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SMITHSONIAN MISCELLANEOUS COLLECTIONS 



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NO. 2 CAMBRIAN FOSSILS FROM MOHAVE DESERT RESSER 






DESCRIPTION OF PLATE 2 

PAGE 

Mesonacis insolcns, new species 8 

Fig. I. Poorly preserved carapace giving some idea of the shape and 
general characteristics of the species. Cotype. U. S. Nat. Mus., 
Cat. No. 78386. 

2. Well preserved cephalon beside the hypostoma of Mesonacis frc- 

monti. Cotype. U. S. Nat. Mus., Cat. No. 78387. 

3. Small cephalon illustrating the size and position of the eyes and 

the glabella. Note the occipital spine. Cotype. U. S. Nat. Mus., 
Cat. No. 78388. 

4. A larger head in which the full size of the advanced genal spines 

is shown. Cotype. U. S. Nat. Mus., Cat. No. 78389. 

Mesonacis hristolensis, new species 7 

Figs. 5, 6. Cephalon and enlarged ( X 4) view of the glabella showing 
the surface features. Cotype. U. S. Nat. Mus., Cat. No. 78390. 

7. Another cephalon with a fairly complete glabella. Cotype. U. S. 

Nat. Mus., Cat. No. 78391. 

8. Fairly complete cephala of this species and of M. insolens, show- 

ing the different angles at which the genal spines arise. Cotype. 
U. S. Nat. Mus., Cat. No. 78392. 

Mesonacis fremonti (Walcott ) 6 

Fig. 9. Portion of the thorax near the posterior end. Plesiotype. U. S. 
Nat. Mus., Cat. No. 78385. 



14 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 



DESCRIPTION OF PLATE 3 

PAGE 

Pacdnniias clavki, new species 9 

Fig. I. A specimen preserving the major portion of the thorax. Note 
the narrow rim and the median ridge between it and the 
glabella. Two other cephala occur on the same piece of rock. 
Cotype. U. S. Nat. Mus., Cat. No. 78393. 
2. Larger cephalon with eyes and glabella well preserved. Cotype. 
U. S. Nat. Mus., Cat. No. 78394. 

Pacdumias ncvadcnsis (Walcott) 9 

Fig. 3. Small, but fairly complete cephalon. Plesiotype. U. S. Nat. Mus., 
Cat. No. 78395- 

4. Large cephalon showing the intergenal spines. Plesiotype. U. S. 

Nat. Mus., Cat. No. 78396. 

5. Another large cephalon, somewhat crushed, causing this specimen 

to resemble P. clarki. Plesiotype. U. S. Nat. Mus., Cat. 
No. 78397. 

6. Smaller cephalon with the glabella better preserved. Note the 

occipital spine. Plesiotype. U. S. Nat. Mus., Cat. No. 78398. 

7. Cephalon complete on the left side, showing position and size of 

the genal spine. Plesiotype. U. S. Nat. Mus., Cat. No. 78399. 

Mesonacis fremonti (Walcott ) 6 

Fig. 8. Enlargement ( X 4) of the left rear quadrant of the hypostoma 
shown on plate i, figure 9. Plesiotype. U. S. Nat. Mus., Cat. 
No. 78384. 

Dolichotnetopiis ? lodcnsis (Clark) 10 

Fig. 9. The smaller shield shows the general characters of this species. 
The larger, less complete carapace is referred to DoUchometo- 
pus productus. Holotype. U. S. Nat. Mus., Cat. No. 78400. 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOL. 81. NO. 2, PL. 3 





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SMITHSONIAN MISCELLANEOUS COLLECTIONS 

VOLUME 81, NUMBER 3 



MORPHOLOGY AND EVOLUTION OF THE 
INSECT HEAD AND ITS APPENDAGES 



BY 

R. E. SNODGRASS 
Bureau of Entomology 




(Publication 2971) 



CITY OF WASHINGTON 
PUBLISHED BY THE SMITHSONIAN INSTITUTION 

NOVEMBER 20, 1928 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 

VOLUME 81, NUMBER 3 



MORPHOLOGY AND EVOLUTION OF THE 
INSECT HEAD AND ITS APPENDAGES 



BY 
R. E. SNODGRASS 

Bureau of Entomology 



S*^li(^,5"^' 






[is: 



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(Publication 2971) 



CITY OF WASHINGTON 

PUBLISHED BY THE SMITHSONIAN INSTITUTION 

NOVEMBER 20, 1928 



BALTIMOriE, MD., V. S. A. 



MORPHOLOGY AND EVOLUTION OF THE INSECT HEAD 
AND ITS APPENDAGES 

By R. E. SNODGRASS 
Bureau of Entomology 

CONTEXTS PACK 

Introduction 2 

I. Evolution of tlie arthropod head 2 

Cephalization 3 

Development of the body iit segmented animals 12 

The protocephalon 19 

The definitive arthropod head 27 

II. General structure of the insect head 33 

The head capsule 34 

The labrum and epipharynx 41 

The stomodeum 42 

The hypopharynx 45 

The tentorium 50 

III. The head appendages 56 

The antennae 57 

The postantennal appendages 59 

The gnathal appendages 60 

The mandibles 62 

The first maxillae 74 

The second maxillae 77 

Morphology of the gnathal appendages 79 

IV. Summary of important points 9° 

V. The head of a grasshopper 94 

Structure of the cranium 95 

The antennae 99 

The mandibles ^0° 

The maxillae 102 

The labium 106 

The preoral cavity and the hypopharynx 107 

The stomodeum 112 

The mechanism for moving the head 118 

VI. Special modifications in the structure of the head 120 

Modifications in the fronto-clypeal region 120 

Modifications in the posterior ventral region of the head 125 

VII. The head of a caterpillar 131 

Structure of the head capsule • ^3~ 

The antennae ^37 

The mandibles ^38 

The maxillae and lal)ium I39 

The stomodeum ^45 

The musculature of back of head, and nature of insect neck 150 

Abbreviations used on the figures 153 

References ^55 

Smithsonian Miscellaneous Collections, Vol. 81, No. 3 



2 SMITHSOMAX MISCKLLANEOLS CULLECTlUXS VOL. 8l 

INTRODUCTION 

Tt is regrettable that we must arrive at an understanding of things 
by way of the human mind. Lacking organs of visual retrospection, 
for example, we can only hold opinions or build theories as to the 
course of events that have preceded us upon the earth. Knowledge 
advances by what biologists call the method of trial and error, but the 
mind can not rest without conclusions. Most conclusions, therefore, 
are premature and consequently either wrong or partly wrong, and, 
once in every generation, or sometimes twice, reason back tracks and 
takes a new start at a different angle, which eventually leads to a new 
error. By a zigzag course, however, progress is slowly achieved. Error, 
then, is a byproduct of mental growth. It is not a misdemeanor in 
scientific research unless the erring one clings to his position when he 
should see its weakness. It is better to write beneath our most positive 
contentions that we reserve the right to change of opinion without 
notice. The reader, therefore, should not take it amiss if he finds 
certain conclusions drawn in this paper that do not fit with former 
statements by the writer, for no apology will be ofifered. 

I. EVOLUTION OF THE ARTHROPOD HEAD 

The head, as a dififerentiated region of an animal, is a more ancient 
structure than is any other specialized part of the body, and a proper 
understanding of the head structure involves an examination of the 
evidence of cephalic evolution from the very earliest period when 
evidence of head development can be found. Most of the Arthropoda 
have well developed heads, and that the arthropod head is a specialized 
body region, just as is the thorax or the abdomen in forms where these 
body regions are difi:'erentiated, is shown by the fact that in the embryo 
it consists of a series of body segments. In most cases, and particularly 
in insects, however, the head differs from the other body regions in 
that its component segments become so thoroughly consolidated in 
the adult as to leave little evidence of the primitive elements in the 
head structure. Even in the ontogenetic record the true history of the 
head development is so oljscure in many respects, and so much deleted 
in the early passages, that, though all the facts of embryology were 
known, it is probable that the assembled information would still give 
but an incomplete account of the phylogenetic evolution of the head. 
It is only by a comparative study of the head structure and its develop- 
ment in the various arthropod groups, and by an effort to correlate 
the known facts of arthropod organization with what is known in 
other animals successively lower in the scale of evolution, that we 



NO. 3 



INSECT HEAD SNODGRASS 



may arrive at a satisfactory conclusion as to the steps by which the 
complex head of an insect has been evolved— and even then we must 
allow much for errors of judgment. 

CEPHALIZATION 

It has been but little questioned that the numerous groups of meta- 
zoic animals are derived from a creature resemliling the 1)lastula of 
embryonic development (fig. i A). The embryonic blastula is exem- 
plified, among living animals, in the early stage of the free-swimming 
larval'planula of the Coelenterata (fig. 2 A). The planula develops 



Bid 




Fig. I. —Typical early stages in general embryonic development. 
A hlastula stage diagrammatic, consisting of a blastoderm (SW) surround- 
ing a blSocoele' cavity" (BIc). B, C, D,. stages in development of a chUon 
Cfrotn Kowalevskv i88^) : B, d fferentiation of cells m blastula, L, gastruia 
^,on 7oS gast icoele cavit; (GO. lined with endoderm (tud), and opemng 
through blaftfpore (Bp) ; D, later stage, showing ongm of mesoderm layers 
(Msd) just within lips of blastopore. 

directly from the coelenterate egg, and has the form of a hollow mass 
of cells the outer surface of which is covered with vibratde cilia. 
The uniform motion of the cilia propels the animal through the water 
in the direction of one axis of the body (fig. 3), and thereby one end 
is distinguished as anterior and the opposite as posterior. The creature 
thus becomes uniaxial and bipolar, though as yet there may be no 
differentiation of body structure. The functional differences at the 
two poles of the body, however, determine the course of the subse- 
quent development of physical characters. Structural dififerentiation 
of the end of the body that is forward in usual progression is called 
cephalization, a term meaning the process of evolving a head. 



SMITHSONIAN MISCELLANEOUS COLLECTKJNS 



VOL. 



The body of the planula is usually larger at the anterior end 
(figs. 2,3), and only in this does the planula attain cephalization in 
the Strict sense. Its principal structural dififerentiation occurs at the 
posterior pole, where there takes place an ingrowth of cells 
(fig. 2 B-D) that soon fills the hollow of the body, and finally, by the 
appearance of a cavity within its mass, becomes the wall of the stomach 
of the mature animal. The process of forming a primitive stomach, or 
archenteroii. as it takes place in the planula, is typified by that of 
gastrulation in ordinary embryonic development (fig. i A-D). The 
planula, of course, is a specialized larval form, and its manner of 
cndoderm formation can not be taken as showing how the archenteron 
was evolved, but the free-swimming planula does show that the primi- 
tive mouth, or hlasfoporc (fig. jC,D,Bp), was formed at the 




A 



B 



C 



D 



Fig. 2. — Formation of the endoderm in a coeleiiterate planula larva by pro- 
liferation of cells from posterior pole. (From Hatschek, 1888, after Claus.) 

Blc, blastocoele ; Pld, blastoderm ; Bed, ectoderm ; End, endoderm. 

posterior pole of the body, and not at the anterior pole. It is interest- 
ing to note, therefore, that the position of the mouth opening was 
not necessarily a primary determining factor of cephalization ; the 
practical site for a mouth in a free-swimming, ciliate animal was 
determined by the direction of the animal's movement. Korschelt 
and Heider (1895) have stated, if a monaxial, heteropolar planula is 
allowed to swim through water containing particles of carmine, it 
can be seen that the particles are rej^ulsed at the anterior and lateral 
parts of the body, but that they accumulate at the posterior pole. 
'' Here accordingly," say Korschelt and Heider, " was a favorable 
place for the reception of particles of food, and by a flattening or 
shallow invagination of the posterior pole these favorable conditions 
were increased. The archenteron, therefore, in its earliest beginnings 
was a pit in which to catch particles of food." 



NO. 3 INSECT HEAD— SNODGKASS 5 

This is a satisfactory explanation of the origin of the gastrula if 
not questioned too closely; but Bidder (1927) rather disturbs the 
idea with his statement that " the laws of viscous matter make it clear 
that the free-swimming gastrulae we observe as larvae could never 
earn their own living, since the stream-lines would carry every particle 
of food outside the cone of dead water which is dragged behind the 
gastrula mouth." On the other hand, Bidder admits, '" creeping 
planulae or gastrulae might pick things up." A creeping animal, 
however, would never in the first place develop a mouth at the rear 
end of the body. What we want is an explanation of the original 
posterior position of the blastopore, and if none offered will sufifice. 
we must be content with the fact. 

The further history of the coelenterate larva has no bearing on the 
evolution of insects, for the creature soon becomes attached by its 
head end, and. probably as a result of the sedentary, plant-like habits 




Fig. 3. — Free-swimming plaiuila larva of a coelenterate, Sympodiuin corral- 
1 aides, with ciliated ectoderm, and completeb'-formed endoderm. (From Ko- 
walevsky and Marion, 1883.) 

of its immediate ancestors, develops into a polype or jellyfish having 
a radiate, flower-like type of structure. Some writers have suggested 
that the worms and the arthropods may have been evolved from an 
elongate medusa, but it seems more probable that the Coelenterata, 
the Annelida, and the Arthropoda are all to be traced back to a free- 
swimming gastrula ancestor. The mature planula is a specialized 
gastrula, but it is of general interest in that it gives us a ])assing 
glimpse of a free-living animal in the blastula and gastrula stages at 
a time when cephalization was first established in the Metazoa. 

The structure and development of the arthropods suggest that 
these creatures were developed from forms adapted to a creeping 
rather than a swimming mode of progression. Some planula larvae 
lack cilia and have creeping habits, and such forms, though they have 
nothing to do with the arthropod ancestors, show that a free-living 
creature in the blastula or gastrula stage may change its mode of 
])rogression. The creeping habit as an habitual mode of progression 
entails some fundamental structural adaptations. An animal that crawls 



6 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

must keep one surface against the support, and thus it estabHshes a 
functional distinction between its upper surface and its lower surface, 
which has led to the structural differentiation of dorsivcntrality ; and 
from this, in combination with movement in one direction, finally, 
bilateral symmetry of organization necessarily follows. 

Progression by crawling instead of by swimming alters the whole 
status of the relation between the animal and the environment. A 
mouth at the posterior end of the body now becomes quite impracti- 
cable, and embryonic history shows that crawling animals proceeded to 
rectify the defect, supposedly inherited from their free-swimming 
ciliate ancestors, by lengthening the mouth, or blastopore, in a for- 
ward direction on the under side of the body. In the young Peripatus 
embryo, for example (fig. 4 A, B), the l)lastopore is a long slit on the 




Fig. 4. — Early stages in the development of Peripatus capensis. (From Balfour, 
1883.) 

The blastopore {Bp) elongates on ventral surface of embryo, and then 
closes except at the two ends (C) where open extremities become mouth and 
anus. Segmentation appears as series of coelomic sacs in mesoderm (see fig. 6, 
Msd). 

ventral surface of the blastoderm. Later, the edges of the slit come 
together (C) and unite except at the two ends, where openings re- 
main into the archenteron that become the mouth and anus of the 
mature animal. In insects and other arthropods, the process of gas- 
trulation in the embryo (fig. 5 A) is clearly a modification of that in 
Peripatus, by which many of the details have been omitted and the 
whole procedure greatly altered. In most insects (fig. 5B), gastru- 
lation resembles that of the planula (fig. 2) in so far as it takes place 
by an internal proliferation of cells from the blastoderm, but most 
of the gastrulation area gives rise to mesoderm, the true endoderm 
being formed only at the two extremities of the inner layer (fig. 5 C, 
AMR). 



NO. 3 



INSECT HEAD SNODGRASS 



The mesoderm, and the associated mesenchyme, play an important 
part in the organization of all the higher Metazoa, since they form the 
internal organs that lie hetween the ectodermal covering of the body 
and the endodermal epithelium of the alimentary canal. The meso- 
derm is of particular importance in segmental animals because it is 
in this layer that metamerism originates. Mesoblastic tissue is pro- 
duced in a gastrulated embryo in two ways : First, in the form of 
scattered cells proliferated from the inner surface of the invaginated 
endoderm ; and second, in the form of cell layers. The scattered cells 



Pre 





B r/ Asd 
Bp 



Ecd 



AMR 




Msd 



Ecd 



Fig. 5. — Gastrulation in insects. 

A, embryo of Lcptiuotarsa deciml'mcata with long gastrulation groove, or 
blastopore {Bp), on ventral surface. (From Wheeler, 1889.) 

B, cross section through blastopore of embryo of Forficula, showing mesoderm 
(Msd) formed by invagination of middle plate. (From Heymons, 1895.) 

C, anterior mesenteron, or endodermic, rudiment (AMR) formed at anterior 
end of mesoderm (Msd) in embryo of honeybee. (From Nelson, 1915.) 

form a loosely coherent mesenchyme ; the cell layers constitute the 
true mesoderm. The primitive mesoderm cells are given ofif from the 
endoderm near where the latter joins the ectoderm, that is, just within 
the lips of the blastopore (figs, i D,6, Msd). In the young annelid 
larva, the mesoderm cells first form two lateral bands of tissue at the 
posterior end of the body (fig. 7 D, Msd). Later, the extended meso- 
derm tracts become excavated by a series of cavities, the coelomic 
sacs, which mark the beginning of segmentation. In Pcripatiis (fig. 4), 
likewise, two rows of coelomic sacs {Msd) are formed as paired 
cavities in the mesoderm, which extends laterally between the ecto- 
derm and the endoderm along the line of junction between these two 



8 



SMITHSONIAN AnSCELLANEOUS COLLECTIONS 



vor 



8 1 



layers (fig. 6,Msd). In the annelids, the coelomic sacs form the 
entire segmented body cavity ; in Pcripatus and most of the arthropods, 
the greater part of the definitive body cavity is derived from a space 
between the ectoderm and the endoderm lined with mesenchymatic 
cells. 

It is most important to bear in mind the intimate relation that exists 
between the mesoderm and the endoderm. In the arthropods, especi- 
ally in insects, the process of gastrulation, as above noted, is greatly 
modified, and mesoderm tissue alone is proliferated along the greater 
part of the length of the blastopore area, which in only a few general- 
ized forms appears as a true opening. At each end of the mesoderm, 
however, endodermal tissue is formed (fig. 5 C, AMR), and the two 




~-M5d- 



FiG. 6. — Formation of mesoderm in Peripatiis cafciisis. (From Balfour, 1883.) 

Cross sections of embryos through blastopore, showing formation of meso- 
dermic coelomic sacs (Msd) from endoderm (End) just within lips of blasto- 
pore (Bp). 




endoderm rudiments mark the anterior and the posterior limits of 
the mesoderm — consequently, they define the area of segmentation. 

It is unnecessary to speculate as to the phylogenetic steps that may 
have led from the early creeping gastrula form of animal to the worm- 
like ancestor of the arthropods, but we must note the important 
advance in cephalization, and the possibilities of further head develop- 
ment that came with the establishment of a mouth at the anterior end 
of the body. Food, whether living or inert, had now to be recognized 
and seized on contact. Consequently, it became highly important to 
the animal to be able to determine its course according to favorable 
or unfavorable conditions of the surroundings. The ectoderm of the 
anterior end of the body developed a special sensitiveness to environ- 
mental changes, and, probably by means of ectodermal processes ex- 
tending into the body, communicated the stimuli received from with- 
out to the internal tissues. Certain groups of the sensitive cells then 



NO. 3 INSECT lIEAll SXODCRASS 9 

were withdrawn into the hody where they became the rudiments of a 
central nervous system. Other sensory cells, remaining at the surface 
but sending processes inward to the buried cells, formed the peripheral 
sensory system. This anterior differentiation of sensory and con- 
ductive tissues opened still other possibilities of cephalization, which 
have led to the development of the brain and all the com])lex sense 
organs located on the head in higher animals. 

It is difficult to establish, by concrete example, the contention that 
the change in the position of the mouth resulted from a change in the 
manner of locomotion, but it is indisputable that the ancestors of the 
worms and the arthropods must have assumed the crawling habit at 
some stage in their evolution. The chaetopod annelids, in their em- 
bryonic development, arrive at a first larval stage known as a trocho- 
phore (fig. 7 D), which is a free-swimming creature with well differen- 
tiated anterior and posterior poles, and a dorsal and a ventral surface, 
with the mouth situated anteriorly in the latter. If dorsiventrality is 
to be attributed to a creeping mode of locomotion, then there must 
be some stage omitted between that represented by the free-swimming 
planula, and that of the free-swimming trochophore, because there is 
no evident reason, otherwise, why two forms having the same mode 
of life should have an organization so different. The trochophore is 
without doubt a specialized larval form modified secondarily for a 
swimming habit. It can not, therefore, be taken to represent an an- 
cestral form of the worms ; but it is the only free-living creature that 
shows us the beginning of the worm organization, and its structure 
can certainly be traced into that of the arthropods. 

The annelid trochophore is typically ovate in shape with the larger 
end forward (fig. /D), or rather, upward, since the creature floats 
upright in the water, but the side in which the mouth (Mth) is located 
is called the ventral surface because it becomes the under surface of 
the mature worm. The mouth lies a little below the middle of the 
body, and the anus (Aji) is situated at the posterior pole. The body 
is surrounded by several bands of vibratile cilia. The principal band 
(b), comprising usually two rows of cilia, is situated on the widest 
part of the body and just before the mouth. It divides the animal into 
a preoral, or prostornial, region (Pst), and into a postoral, or iiictas- 
tomial, region (Mst). A second band of cilia (c) is generally present 
a short distance behind the mouth, and sometimes there is a third, 
preanal band (G, d) near the posterior end, which sets off a terminal 
circumanal region, or pcriproct (Ppt). At the anterior end of the 
body there is a central tuft of tactile hairs (G, a), a pair of small 
lateral tentacles (Tl), and one or more simple eye spots (0). 



10 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 



The mouth of the trochophore (fig. 7 D, Mth) opens into an ecto- 
dermal stomodeum (Stoiii), which leads into a large endodermal 
stomach, or mesenteron (Ment), of two parts, the second of which 
communicates with the exterior through a short ectodermal procto- 



M5b 




Mth 

^M5t 



VMcl 



VNv 



Fig. 7. — Structure and development of an annelid trochophore larva. (From 
Hatschek, 1888-91, but figures A to F turned in position of adult worm with 
mouth downward.) 

A, blastula stage with endoderm cells (End) differentiated at posterior pole. 
B, gastrulation, showing a primitive mesoblast cell (Msb) of one side. C, 
gastrulation completed, mesenteron {Mcnt) detached from ectoderm at posterior 
end, its anterior end opening through stomodeum (Stoni) and mouth. D, full- 
grown trochophore larva of Polygordhis. E, diagrammatic view of the muscle 
system. F, the nervous system. G, ventral surface of a trochophore. 

a, apical tuft of cilia; An, anus; AP, apical plate; b, preoral band of cilia; 
BIc, blastocoele ; Bp, blastopore : c, postoral band of cilia ; d, circumanal band of 
cilia; DMcl, dorsal muscle; DNv, dorsal nerve; End, endoderm; Ment, mesen- 
teron; Msb, primary mesoblast cells; Msd, mesoderm; Mst, metastomium ; Mth, 
mouth ; Nph, nephridium ; O, eye spot ; Ppt, periproct ; Proc, proctodeum ; Pst, 
prostomium ; Stoni, stomodeum ; TI, tentacle ; VMcl, ventral muscle ; ]''Nv. 
ventral nerve. 

demn {Proc) . In development, the endoderm is formed by invagina- 
tion at the posterior end of the body (fig. 7A, B, iiwrf), but the 
blastopore {Bp) soon shifts to the ventral surface (C) and elongates 
forward. The posterior part of the blastopore is then closed ; the 



NO. 3 INSECT HEAD SNODGKASS II 

anterior open extremity is carried inward by an ectodermal invagina- 
tion which becomes the stomodeum (C, Stom), the external opening 
of which is the definitive mouth (Mth). The proctodeum and the 
anus are formed later by a posterior invagination of the ectoderm, 
and the proctodeum secondarily opens into the posterior end of the 
stomach. At the anterior end of the preoral region of the body, or 
prostomium, the ectoderm is thickened to form a sensory apical plate 
(D, G, AP) beneath the sensory organs here located, and from it 
ectodermal nerve tracts extend posteriorly in the body wall (F). 
Typically, there is a pair of dorso-lateral longitudinal nerves (DNv), 
and a pair of ventro-lateral nerves (VNv). The simple musculature 
of the trochophore (E) is developed from mesenchyme tissue; the 
epithelial mesoderm forms only the pair of mesoderm bands (D, Msd) 
and a pair of nephridia (Nph) in the posterior part of the body. 
This description of the trochophore is based mostly on that of Hats- 
chek (1888-1891), from whose work the illustrations of figure 7 are 
taken. 

The trochophore develops into the worm form of its parents by a 
metamorphosis involving an elongation of its posterior end (fig. 9), 
accompanied by a reduction of the cephalic swelling, until finally, in 
the adult, the only dififerentiation in the head region is an anterior, 
median prostomial lobe overhanging the mouth (fig. 10, Pst). The 
prostomium usually bears the principal sensory areas or organs of 
the worm, and a ganglionic nerve mass is differentiated from the 
inner surface of its ectoderm, which becomes the supraoesophageal 
ganglion, or brain, of the annelid. In the Polychaeta, the prostomium 
may bear one or more pairs of eyes, and several pairs of sensory ten- 
tacles (fig. 10). As the body of the young worm elongates, it be- 
comes transversely segmented, the somites increasing in number 
posteriorly as the segmented area lengthens. 

The young arthropod embryo, in its first definite form (fig. 8 A), 
consists of a large head region, the so-called cephalic lobes (Pre), and 
of a slender body (Bdy). The mouth (B, Stom) is situated on the 
ventral surface of the cephalic enlargement. The proctodeal invag- 
ination and the anus are formed, usually in a later stage, at the pos- 
terior end of the body. 

The large-headed stage of the young arthropod embryo has a cer- 
tain resemblance to the trochophore stage of the annelid larva ; but it 
is probable that the similarity between the two forms has no genetic 
significance, and that the size of the cephalic lobes in the arthropod 
embryo is to be explained as an acceleration of development. Yet, 
it is evident that the cephalic region of the arthropod embryo cor- 



12 



SM iTHSOXlAX M ISCKLLANEOUS COI. LECTIONS 



NUE. 



8l 



responds with the prostomial and metastomial regions of the trocho- 
phore, and includes also the next following somite, for the first an- 
tennae, which are the appendages of the second somite of the arthro- 
pods, are developed on the cephalic lobes of the embryo (fig. 8 B, C. 
'D.Avt). In the insect embryo, furthermore, the region of the rudi- 
mentary second antennal appendages, or the tritocerebral segment 
(fig. 8 C, ///), is often incorporated into the cephalic lobes. It is 
probable, therefore, that the very early insect embryo represents a 
higher stage of cephalic evolution than does the annelid trochophore 



Pre 




.Pre 



-Ant 



Pre 



Pnt 




C 



Fig. 8. — Young stages of insect embryos, showing cephalic lobes, beginning 
of segmentation, and formation of appendages. 

A, germ band of Blatclla gcnnanica on seventh day, with cephalic lobes {Pre) 
indicated. (From Riley, 1904.) 

B, embryo of same, about nine days old, with cephalic lobes developed into 
a distinct protocephalon (Pre), antennae (Ant) appearing, stomodeum iStotn) 
indicated as thickening of ectoderm. (From Riley, 1904.) 

C, young embryo of Lcpisiiia, with well -developed protocephalon (Pre), 
bearing stomodeum and rudiments of antennae, with tritocerebral segment 
(///) closely associated with its base. (From Heymons, 1897.) 

D, embryo of BhilcUa late in tenth day, with labrum (Lm) , mouth (Mth), 
and antennae (Ant) on protocephalon {Pre), followed by rudiments of post- 
antennal appendages (Put), mandibles (Md), first maxillje (iMx), second 
maxillje (jAIx), and legs (Li). (From Riley, 1904.) 

larva, in as much as it has already progressed to a point where the 
head includes two or three of the body segments. 

The definitive head of the arthro])od may contain as many as six or 
seven of the body segments. Before going farther in the study of 
]irogressive cephalization. then, it will be necessary to understand 
something of the development and general organization of the body 
in segmented animals. 



r>i:\EL01^MENT OF THE BODY IN SEGMENTED ANIMAL.S 

In the Annelida, the worm form is developed from that of the 
trochophore by an elongation of the posterior part of the larval body 



NO. 3 



INSECT HEAD — SNODC.KASS 



13 



(fig. 9), and by a decrease in the relative size of the cephalic enlarge- 
ment. The young worm is a cylindrical creature with only a com- 
paratively small prostomial lobe projecting before the mouth. With 
the elongation of the body, the alimentary canal and the mesoderm 
bands are correspondingly lengthened, and the trochophore muscles 
and nerves are continued into the new region. The external surface 
of the body of the trochophore is marked ofif into several areas by 
circular bands of cilia ; the worm body, on the other hand, is con- 
stricted by transverse grooves into a series of segments, or somites. 
The segmentation of the adult worm originates in tJie mesoderm 
bands by the development in the latter of a series of paired coelomic 
sacs. Secondarily, the mesodermic divisions become impressed u])on 




-Ment 




A 

Fig. 9. — Diagrams of the development of an annelid trochophore larva, and 
early stage in its metamorphosis into a segmented worm. (F"rom Hatschek, 
i888-'9i.) 

A, early larval stage, showing a primary mesohlast cell {Msh) of one 
side. B, later stage in which the mesoblast has formed scattered mesenchyme 
cells (Msc), and a ventro-lateral band of mesoderm (Msd) in each side of the 
body. C, early stage of metamorphosis in wliich each mesoderm band has 
divided into a number of primary segments. 

the body wall, and the segmentation expressed externally by a series 
of transverse, circular grooves on the intersegmental lines. In the 
worms, the segments increase in number from before backward by 
the differentiation of new segments between the last one formed and 
the periproct. The latter remains as an undifferentiated terminal piece 
of the body bearing the anus. The prostomial region of the trochophore 
becomes the prostomium of the adult worm; the metastomial region 
in the Archiannelida constitutes the first body segment, or that im- 
mediately behind the mouth ; but in the Polychaeta and Oligochacta 
the metastomium is said to unite with the next somite to form a com- 
pound peristomial segment. 

In the adult annelid (fig. 10), the body, as distinguished from the 
head, is all that part of the worm that lies posterior to the mouth 
(A, MfJi), and the only differentiated head region is the prostomium 



14 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8 1 



(Pst), though the peristomium (Prst) is sometimes called a part of 
the " head ". The prostomium varies in size from a small lobe over- 
hanging the mouth, to a large area extended posteriorly into the 
dorsal region of the peristomium (B). It bears the principal sensory 
organs, eyes and tentacles (O, TI), of the anterior part of the worm. 
The alimentary canal extends entirely through the body from the 
mouth at the anterior ventral edge of the peristomium to the anus 
at the end of the periproct. 

The nervous system of the adult annelid consists of a brain located 
before or above the oesophagus, derived from the ectodermal apical 
plate of the prostomium of the trochophore (fig. 7 F, AP), and of 
a ventral nerve cord of segmental ganglia and intervening connec- 
tives, formed from two nerve strands developed from the ectoderm 





Fig. 10. — Anterior end of an adult polychaete annelid worm, Nereis virens. 

A, lateral view. B, dorsal view. 

Mth. mouth; 0, ocellus; Pip, prostomial palpus; Ppd, parapodium ; Prst. 
peristomium ; Pst, prostomium ; Tl, prostomial tentacles. 

of the ventral body wall and prolonged from the ventro-lateral nerve 
strands of the trochophore. The ventral cord, therefore, is connected 
with the brain by a pair of connective nerve cords passing to the sides 
of the oesophagus. Usually, the two ventral nerve strands are united 
along the midline in adult worms, but in certain polychaete forms 
(Serpulidae) the two cords are said to remain separate, though con- 
nected by transverse, interganglionic cominissures in each segment. 

In the Arthropoda, body segmentation begins during an early em- 
bryonic stage, and the somites are added, in general, as in the annelids, 
from before backward by the differentiation of new segments behind 
the last one formed. In some of the arthropod groups, segmentation 
is completed in a postembryonic stage; in insects (except Protura), 
however, the somites are all defined before the creature leaves the 
Qgg, and the typical sequence of segmentation is not always followed. 



NO. 3 INSECT HEAD SNODGRASS I 5 

The component segments of the cephalic loljes, or head of the arthro- 
pod embryo, are never distinct, but the subsequent development of 
the anterior nerve centers shows that the lobes comprise two segments 
at least, in addition to a prostomial region, and that usually a third 
segment is more or less included in their posterior part. 

The way in which metamerism arose in the phylogenetic history of 
segmented animals is not known, and it is not necessary to believe 
that the method of segment formation in either the annelid larva or 
the arthropod embryo gives a picture of primitive segmentation in 
the course of evolution. The development of the trochophore into the 
worm is clearly a process of metamorphosis, that is, it is the return 
of a specialized, aberrant larva to the ancestral form represented more 
nearly in that of the adult ; and it is well known that embryos do not 
keep closely to the phylogenetic path in the details of their development. 
Since so many other essential features in the body structure of animals 
are connected with the mode of locomotion, the writer holds as most 
probable the idea that segmentation also had its beginning as an 
adaptation to a specific kind of movement. The creeping, worm-like 
ancestors of the annelids and arthropods certainly at an early period 
must have developed a contractile tissue in their mesoderm bands — - 
that they did so is attested by the early development of a central 
nervous system consisting of motor neurons, following the lines of the 
later established ventral longitudinal muscle bands. It is, then, clear 
that a breaking up of the contractile tissue into short lengths would 
give a greater efficiency of movement, with the possibility of more 
variety of action, and that, wdth the differentiation of true muscle 
fibers, the attachment of the ends of the fibers to the ectoderm would 
carry the metamerism into the body wall. The fact that embryonic 
segmentation begins anteriorly and progresses backward, in itself 
suggests that metamerism originated in a creeping animal ; in a free- 
swimming form, the progress of segmentation should be the reverse, 
for the motile region of the animal would be the tail end. Organs de- 
veloped at the time of metamerism or subsequent to it, such as ne- 
phridia, tracheae, and external appendages, are repeated in each seg- 
ment, those antedating segmentation either remain unsegmented, as 
the alimentary canal, or take on a secondary segmentation, as do the 
body wall and the nervous system. 

There are other theories of metamerism: Hatschek (i 888-1 891) 
enumerates five views that have been proposed to explain the origin 
of body segmentation, but none of them is based on the simple fact 
that in embryonic development, metamerism begins in the mesoderm 



i6 



SMITHSONIAN M iSCKLLANEOUS COLLECTIONS VOL. 8l 



and secondarily spreads to other tissues. The older locomotion theory 
was defective in that it attributed the formation of segments to the 
mechanical stress of movement. 

At the completion of metamerism, a segmented animal has attainel 
a generalized structural stage in which it consists of a segmented body 
part coextensive with the length of the alimentary canal (fig. ii), 
and of a prostomial region (Pst) anterior to the mouth (Mth). Since 
the mouth in annelids and arthropods marks the site of the original 
anterior extremity of the blastopore on the ventral surface of the 
body (figs. 4 B, 5 A, Bp), it is evident that nicsodcniuil segments can 
not be formed morphologically anterior to the mouth, and therefore, 
that the preoral region is never truly segmented. The common idea, 
then, that the arthropod mouth lies behind the first head segment, or, 
as proposed by some writers, behind the second or even the third seg- 



Stom 



Ment 



Proc 




VNC 
-Diagram of the structure of a theoretically generalized segmented 



Fig. II.— 
animal. 

An, anus; Arc, archicerebrum : Mcut, mesenteron; Mth, mouth; Ppt, peri- 
proct; Proc, proctodeum; Pst, prostomium ; Stoiii, stomcdeum; VNC, ventral 
nerve cord. 



ment, disregards the fundamental relation between the endodermal and 
mesodermal layers. Segmentation can not exceed the extent of the 
mesoderm, and the primitive extent of this layer in the annelids and 
arthropods is defined by the positions of the mouth and the anus. The 
blastopore never extends quite to the true cephalic extremity. The 
stomodeal invagination, which gives rise to the definitive mouth, is 
thus preceded by an unsegmented prostomium. The closed posterior 
end of the blastopore, however, is at the posterior extremity of the 
body, where the blastopore and endoderm originated, and the later 
formed ]n-octodeum, therefore, opens terminally in the periproct. In 
some arthropods a median lobe, or suranal plate, grows out over the 
anus from the periproct, and simulates the prostomial lobe at the 
anterior end of the body. Likewise, there may be lateral and subanal 
lobes of the periproct. 

In as much as the most important evidence of the segmentation of 
the arthropod head is derived from a study of the cephalic nerve 



NO. 3 



INSECT HEAD SNOUGRASS 



17 



masses, it will be necessary to understand next the essential features 
in the evolution of the central nervous system in segmented animals. 

The annelids, as already noted, have a ganglionic nerve mass lying 
in the anterior part of the body, before or above the stomodeum, 
which takes its origin from the ectodermal apical plate of the pro- 
stomium (fig. 7 F, Ap) . This, the most primitive brain of the annelid- 



Arc 



a,.NC 




Com 




Fig. 12. — Diagrams suggesting the evolution of a central nervous S3'stem of 
annelid-arthropod type of structure. 

A, theoretical structure of nervous system in an unsegmented pre-annelid 
form, consisting of a prostomial archicerebrum (Arc), and of two ventro- 
lateral nerve cords (NC), connected medially by transverse nerves, and giving 
off nerves laterally to body wall and internal organs. Nerve cells dififused along 
the cords. 

B, simple nervous system of the ladder type in a segmented animal. The 
nerve cells aggregated into segmental groups, or ganglia (Gng), along the cords ; 
the intervening parts of cords converted into connectives (Con), and the 
transverse ventral nerves forming commissures (Com) between the ganglia. 

C, the segmental pairs of ganglia united into compound ganglia of a median 
ventral nerve cord (J'NC), in which the first, or suboesophageal, ganglion 
(SocGng) is postoral, and connected with archicerebrum of prostomium (Arc) 
by connectives (CocCon^ encircling the mouth (Mth). 

arthropod series (fig. 12 A, Arc), has been named by Lankester 
(1881) the archicerebrum (a happy, though mismated union of lin- 
guistic elements). In the trochophore, a pair of dorsal and a pair of 
ventral nerves (fig. 7 F, DNv, VNv) extend backward from the 
apical plate, but in the adult worm and in arthropods only the nerves 
of the ventral pair are retained. In the more primitive condition, the 
two ventral nerve strands have a latero-ventral position (fig. 12 A, 



./ 



l8 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

NC), and it seems reasonable to attribute the special development of 
these nerves in a creeping animal to the special development of sensi- 
tivity in the ectoderm along the edges of the body in contact with the 
supporting surface. 

That the nerve strands were primarily unsegmented is shown by the 
fact that they are not ganglionated in the Archiannelida, and by their 
condition in Pcripatiis where the nerve cells are still distributed along 
the length of the cords, and segmental grouping of the cells is but 
slight. A concentration of the nerve cells of the cords in each seg- 
ment is, then, only a simple adaptation to efficiency where metamerism 
l)ecomes the established body structure. After the segregation of the 
nerve cells into pairs of segmental ganglia, the intervening fibrous 
tracts of the cords remain as connectives between the successive ganglia 
in each chain, while transverse ventral nerves, originally going from 
one cord to the other, become commissures uniting the ganglia of 
each segmental pair. In this way, apparently, a simple nervous system, 
formed primarily as two parallel strands of nerve tissue, became a 
segmented system of the ladder type (fig. 12 B) . In the further course 
of evolution, the ganglia of each segment come together medially and 
combine into a single ganglionic mass, or segmental ganglion (C), 
which, in some arthropod groups, acquires an addition from a sec- 
ondary median cord of nerve tissue developed from the ventral 
ectoderm along the midline of the body. The transverse commissures 
are now internal fibrous tracts of each double ganglion, but the length- 
wise cords persist usually as paired interganglionic connectives. Each 
definite body ganglion, or pair of ganglia, innervates, in general, only 
the parts and organs of its own segment, but all the ganglia show a 
tendency to migrate along the cords, especially in a cephalic direction, 
and to unite with other ganglia to form composite ganglionic masses. 
Whatever may be the final position of any pair of ganglia, however, 
its nerves in most cases still go to the segment in which the ganglia 
originated. The nervous system, thus, often gives a key to the body 
segmentation where the latter is obscure or obliterated. 

The next important stage of development is that, characteristic of the 
arthropods, in which are formed the external segmental appendages. 
The organs designated " appendages " in the limited sense are hollow, 
ventro-lateral outgrowths of the body wall (figs. 13, 14, 22), which 
become movable by muscles inserted on their bases, and flexible by a 
series of joints in their walls, also provided with muscles. Here again, 
we connect structural evolution with movement, for undoubtedly the 
segmental appendages in the first place were all organs of locomotion, 
giving a new power of movement supplanting the wriggling and 



NO. 3 



INSECT HEAD SNODGRASS 



19 



creeping of earlier ancestral forms. The question of whether the 
appendages were first used for propulsion through the water, or for 
progression on a solid support will not be discussed here, but, in the 
course of their evolution, the appendages have become specialized to 
serve a great variety of functions. Moreover, by the functional 
grouping of the appendages, the corresponding body segments have 
themselves become differentiated into groups forming often quite 
distinct body regions (fig. 13 B), of which the head of an insect is one 
of the most highly evolved. 





Fig. 13. — Young insect embryos at a stage when the thorax is already 
differentiated, but in which the gnathal segments are not yet added to the 
protocephalon to form the definitive head. 

A, embryo of Lepisma saccharina (from Heymons, 1897). B, embryo of 
Ranatra fusca (from Hussey, 1926). 

Ab, abdomen; Ccr, cercus; Gn, gnathal segments; ///, tritocerebral segment: 
Li, first leg; Lm, labrum ; Md, mandible; iMx, first maxilla; sMx, second 
maxilla ; Pp, " pleuropodium " ; Pre, protocephalon ; Th, thorax. 



THE PROTOCEPHALON 

The arthropods differ from the annelids in the possession of a com- 
posite head, or syncephalon, formed by the union of several of the 
anterior segments with the prostomium. 

In the embryonic development of most Arthropoda the head is 
first differentiated as a swelling of the anterior end of the body, form- 
ing the so-called cephalic lobes (fig. 8 A, B, Pre). On this region are 
developed the labrum (D, Lm), the eyes, the stomodeal invagination 
(B, Stom), or mouth (D, Mth), the antennae (Ant), and in some 
cases the postantennal appendages, when the last are present (fig. 
22 A, 2Ant). The cephalic lobes soon become a very definite em- 
bryonic head (fig. 13A, B, Pre), which either remains as the entire 



20 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8 1 

adult head (certain crustaceans), or constitutes the basic structure to 
which other body segments are added later to form the definitive head. 
It is impossible, therefore, to escape the conclusion that the primary 
embryonic head represents an early phylog-enetic stage of cephaliza- 
tion, which was characteristic of the ancestors of all the arthropods. 
This first arthropod head may be termed the protoccphalon (proceph- 
alon. Patten, 1912) to distinguish it from the prostomial head of the 
annelids, which might fittingly be designated an archie ephalon, though 
Cram]iton (1928a) has proposed this term to denote a later formed 
cephalic region composed of the protocephalon and the mandilnilar 
segment. 

There has been some uncertainty as to the number of segments in- 
volved in the protocephalon, for the segmentation of the cephalic lobes 
is never clearly marked in the eml)ryo, and the existence of primary 
head segments is usually indicated rather by the presence of the head 
appendages, and by the divisions of the cephalic nerve mass, than by 
the appearance of metamerism in the head itself. It appears most prob- 
able, however, for reasons to be given presently, that the protocephalon 
comprises a prostomial region and two or three primitive somatic 
segments. The adult arthropod brain is a syncerebrum, consisting 
always of two parts, the protocerebral and deutocerebral lobes, to 
which in most cases are added the ganglia of a following segment, 
which constitute then the tritocerebral brain lobes. The protocerebral 
lobes are the most complex part of the brain, and they are probably 
formed of elements derived from a primitive prostomial region and 
from the ganglia of a preantennal segment. The deutocerebral lobes 
are simple developments of the ganglia of the antennal segment. The 
postantennal ganglia do not always enter into the composition of the 
definitive brain, and their segment is often not a part of the proto- 
cephalic head of the embryo, as indicated by the position of its appen- 
dages (fig. 8 D, Put, fig. 22 B, C, Ch ; D, Pnt). 

The segmental position of the mouth has been the subject of much 
difference of opinion. Most writers hold that the stomodeal invagina- 
tion is situated in or Ijefore the first true head segment ; others claim 
that it lies l)eliind the second, or even the third segment (Comstock 
and Kochi, 1902; Holmgren, 1909, 1916; Henriksen, 1926). It was 
long ago pointed out by Lankester (1881) and by Goodrich (1898), 
however, that only on the assumption that all the true head segments 
of arthropods are pastoral in position can the arthropod head seg- 
mentation be homologized with the anterior body segmentation of the 
annelids. Whatever part of the head is truly preoral, according to 
this view, belongs to the prostomium. Moreover, Lankester argued, 



NO. 3 INSECT HEAD SNODGRASS 21 

the arthropod brain must contain a median anterior rudiment derived 
from the prostomial ganglionic mass, or archicerebrum, in addition to 
the ganglia of the component segments. " In the Chaetopoda," Lan- 
kester says, " the prae-oesophageal ganglion appears always to remain 
a pure archicerebrum. But in the Crustacea (and possil)ly all other 
Arthropoda * * * ) the prae-oesophageal ganglion is a syn-cerebrum 
consisting of the archicerebrum and of the ganglion masses appropri- 
ate to the first and second pair of appendages which were originally 
postoral, but which have assumed a praeoral position whilst carrying 
their ganglionic masses up to the archicerebrum to fuse with it." 

According to Lankester's view, then, the arthropod head should 
comprise a prostomial region and several postoral segments, and the 
brain correspondingly should include the prostomial archicerebrum 

Clp ^ Prnt 

Lm 



IIIGr 



Ant 







~Md 



A ^-^ B 



iMx 



Fu;. 14. — Young embryos of a chilopod and an insect showing rudiments of 
preantennal appendages. 

A, anterior end of embryo of Scolopcmira (from Heymons, 1901). B, same 
of a phasmid, Carausiiis niorostis (from W'iesmann, 192(1). 

Ant. antenna; Clp, clypeus ; Hphy, hypopharynx ; IIIGng, tritocerebral gan- 
glion ; Lm, labrum ; Md, mandible ; iMx, first maxilla ; 2Mx, second maxilla ; 
Pnit, preantenna. 

and the paired postoral ganglia of the first two segments, with the 
ganglia of the third segment added in most cases. This idea, expressed 
theoretically by Lankester and by Goodrich, has been given substantial 
support by Heymons in his study of the development of Scolopendra, 
and more recently by Wiesmann from a study of the embryo of 
Carausius. 

The head of Scolopendra, Heymons (1901) says, is formed during 
embryonic development by the union of an unsegmented preoral 
region and six postoral segments. The preoral part Heymons calls 
the " acron," taking this term from Janet ( 1899) in a slightly altered 
sense ; it is the primary " Kopfstiick," which clearly is the pro- 
stomium. The first true metamere, or postoral segment, is marked by 
a pair of small coelomic sacs in the mesoderm, and bears a pair of 
evanescent preantennal appendages (fig. 14, Prnt), which at an early 



22 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 



stage lie on a line posterior to the mouth. Later, this segment loses 
its identity, and it can not be traced in the composition of the adult 
head. The second metamere is the antennal segment, bearing the 
antennae of chilopods (fig. 14 A, Ant) and insects (fig. 13 A, Ant), 
or the corresponding first antennae (antennules) of Crustacea (fig. 
22 A, I Ant) . The third metamere is the so-called intercalary segment, 
marked by a pair of coelomic sacs and corresponding ganglia in 
Scolopcndrd (fig. 14 A, IIIGng), bearing the highly developed second 
antennae of Crustacea (fig. 22 A, 2Ant) , the chelicerae of Arachnida 
(fig. 22, B, C, C/i), or the rudimentary post-antennal appendages of 
insects (fig. 22 'D,Pnt). The fourth, fifth, and sixth metameres of 
the definitive chilopod head are the segments of the gnathal appendages 
(fig. 14 A, Md, iMx, 2Mx), which have united with the proto- 
cephalon. 

The adult brain of Scolopendra, Heymons finds, is a composite of 
preoral and postoral ganglionic elements. The preoral parts are de- 
rived from the ectoderm of the prostomial region, the postoral parts 
are the paired ganglia of the first three head metameres. The pro- 
stomial elements include a median archicerebral rudiment that becomes 
the anterior part of the supraoesophageal commissure, and paired 
lateral rudiments, which form the dorsal cortical plate, the frontal 
lobes, and the optic lobes of the definitive brain. The ganglia of the 
first metamere, or preantennal segment, are a pair of small nerve 
masses which unite with the prostomial rudiments to form the proto- 
cerebral lobes of the adult brain. The ganglia of the antennal segment 
constitute the deutocerebrum ; those of the postantennal segment be- 
come the tritocerebral lobes. The definitive location of the preantennal 
and antennal ganglia anterior to the mouth is a secondary one, and 
their union before or above the stomodeum, Heymons explains, comes 
about ontogenetically through the late development of the transverse 
commissures, which are not formed until the respective ganglia ha^'e 
acquired a preoral position. Wheeler (1893) had sviggested that " the 
arthropod protocerebrum probably represents the annelid supraoesoph- 
ageal ganglion, while the deuto- and tritocerebral segments, orig- 
inally postoral, have moved forward to join the primitive brain." 
This essentially is also Heymon's earlier view ( 1895) , but the existence 
of a separate pair of preantennal segmental ganglia was not suspected 
at that tim'e. 

For many years Heymons' observations on the development of the 
head of Scolopendra have remained unverified. It is, therefore, of 
particular interest to find essentially the same structure now described 
for an insect. Wiesmann (1926), studying the development of a 
phasmid. Ca ran si us morosns, reports that the head is composed of 



NO. 3 



INSECT HEAD SNODGRASS 23 



a prostomial region and of six postoral metameres with paired coelomic 
sacs, of which the first metamere bears a pair of small, evanescent 
preantennal appendages (fig. 14 B, Pnit). Wiesmann, however, claims 
that the prostomium is a segment, because he finds in its mesoblastic 
tissue a pair of small cavities at the base of the paired rudiments of the 
labrum. The prostomial region of the adult arthropod contains a part 
of the body lumen, but from this it does not necessarily follow that its 
primitive mesoblastic cavities are homologous with the coelomic sacs 
of the true mesoderm, the extent of which should be limited by the 
length of the blastopore (see page 16). More likely, the mesoblast of 
the prostomium is a mesenchyme. In any case, however, it is only a 
matter of definition as to what we shall call a " segment." 

The assumption of the presence of one or more preoral segments 
in addition to the prostomium disregards the fundamental relation 
between the embryonic germ layers. As already pointed out, the 
position of the mouth, or of the stomodeal invagination, marks the 
anterior end of the blastopore ; the extent of the endoderm, except as 
it expands within the body, is determined by the length of the blas- 
topore; the mesoderm is derived from the endoderm, and in the 
mesoderm metamerism originates. Therefore, in a bilateral animal, 
it seems clear, true segments can not lie morphologically anterior to 
the mouth. In the insect embryo, the anterior mesenteron rudiment 
actually defines the anterior limit of the mesoderm. Later formed 
segmental regions or appendages that appear to be preoral must, then, 
have acquired this position secondarily. In the figure of a Peripatus 
embryo (fig. 4 D) it is clearly seen how the anterior coelomic sacs 
may extend laterally before the mouth, and how corresponding 
appendages might come to have a preoral location topographically, 
though being morphologically postoral. 

In the insect brain, there has never been noted a distinction between 
ganglionic rudiments of a preantennal segment and prostomial ele- 
ments in the composition of the definitive protocerebral lobes, and 
the optic lobes are commonly referred to the first segment, though 
their independent origin is recognized. In the Crustacea, however, pre- 
antennal ganglia have been recorded, and Daiber (1921) says, " since 
ontogeny appears to give support to the view that the optic lobes are 
secondary structures, we must suppose that the segmental gangha of 
the preantennal segment have been mostly suppressed, and that remains 
of them are represented in the ganglion cells of the roots of the oculo- 
motor nerves. The ganglion pair found in the embryo of Astacus and 
lacra between the ganglionic fundaments of the optic lobes and those 



24 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 



of the antennal ganglia, and which later fuse with the brain ganglia, 
are probably to be explained as the true segmental ganglia of the 
preantennal appendages." 

It may be questioned if there is ever a true segmental separation 
between the ocular and antennal region of the insect head, since what- 
ever division does occur between the two parts appears relatively late 
in development, and is, therefore, probably of a secondary nature. 
Holmgren (1916), from a comparative study of the histology of the 
brain of annelids and arthropods, concluded that the protocerebral 
and deutocerebral parts of the definitive arthropod brain are secondary 
subdivisions of one primitive nerve mass, which, moreover, Holmgren 
would identify with the archicerebrum of the annelids. This con- 
clusion is scarcely tenable, because, interpreted literally in terms of 
annelid structure, it would assign the antennae to the prostomium. 
and because it disregards the evidence of the postoral position of both 
the preantennal and antennal rudiments in the embryo. 

It is usually assumed that the compound eyes of crustaceans and 
insects belong to the preantennal segment, which, on this assumption, 
is designated the "ocular" segment. Heymons (1921), however, 
claims that in Scolopendva the eyes and the optic lobes are derived 
from the ectoderm of the prostomial region. It is perhaps not neces- 
sary to believe that the grouped ocelli of the Chilopoda, even the 
composite " pseudo-compound " eyes of Scutigera, are related to the 
true compound eyes of crustaceans and insects, since the details of 
structure in the two cases are quite dififerent ; but it would seem less 
probable that the optic lobes of the brain should have a separate 
origin in the different arthropod groups. In many of the Crustacea, 
the compound eyes are pedunculate, being situated on segmented 
stalks having an ample musculature innervated from the protocere- 
brum, and this fact gives strong support to the idea that the eye- 
stalks are appendages of the preantennal segment. Experiments have 
shown that if an eye-stalk is amputated, an antenna-like organ is 
often regenerated from the stump, on which an eye is not developed. 
These results recall the experiments of Schmitt-Jensen (1913, 1915) 
who cut ofif the antennae of a phasmid (Caraiisius inorosiis) and found 
that the appendages were regenerated in a form closely resembling 
the tarsi of the thoracic legs, each, in some cases, with a pair of ter- 
minal claws and a pulvillus. 

It is difficult to evaluate these regeneration phenomena, for it seems 
highly improbable that the insect antenna ever had the specialized 
structure of the thoracic appendages of modern adult insects. Many 



NO. 3 



INSECT HEAI 



-SNODGRASS 



writers hold that the crustacean eye-stalks are secondary outgrowths ; 
and, as for their innervation from the protocerehral lobes, it might 
be claimed that the roots of the oculo-motor nerves come from a part 
of the protocerebrum derived from the prostomial archicerebrum. A 
definite opinion on these matters must await the results of further re- 
search. Since, however, in the Annelida, the prostomium is the seat 
of primary sensory development, and of the principal sense organs 




AntNv 
^- MdNv 

LbNv 



Fir,. 15. — Evolution of the insect brain as it must be conceived if it includes 
an archicerebral rudiment, and ;/ the compound eyes and the optic lobes are 
derived from the prostomial region, as claimed by Heymons. 

A, theoretical generalized condition in which the ganglia of the prostoinium 
(Pst), preantennal segment (/), antennal segment (//), and postantennal 
segment (///) are yet distinct, and in which the prostomial archicerebrum (Arc) 
is the brain. 

B, the prostomium and the first three postoral segments united into a proto- 
cephalon ; the brain composed of protocerehral lobes (iBr) formed of the 
archicerebrum (Air) and ganglia of preantennal segment (/), and of deuto- 
cerebral lobes (jBr) representing ganglia of antennal segment ( // ) ; ganglia of 
postantennal segment (///) distinct and connected by postoral commissure. This 
condition retained in some lower crustaceans. 

C, the definitive condition in all insects : the ganglia of postantennal segment 
(III) are added to the brain to form the tritocerebral lobes (sBr) of the 
latter; the ganglia of the gnathal segments (/F, V, VI) united in a compound 
suboesophageal ganglion (SocGnc;). 

Aiit, antenna; AntNv, antennal nerve; Arc, archicerebrum; iBr, protocere- 
brum; 2Br, deutocerebrum ; sBr. tritocerebrum ; 3C0111. tritocerebral com- 
missure ; E, compound eye ; LbNv, labial nerve ; Md. mandible ; MdNv, mandib- 
ular nerve ; iMx, first maxilla ; 2Mx, second maxilla ; MxNv, maxillary nerve ; 
O, ocellus, OpL, optic lobe; Put, postantennal appendage; Pre, protocephalon ; 
Pst, prostomium; SocGng. suboesophageal ganglion; Stom. stomodeum. 

(fig. 10), it is at least in harmony with the assttmed annelid ancestry 
of the Arthropoda to suppose that the arthropod eyes had their origin 
on the prostomial region of the head, and that their definitive posterior, 
dorsal location has resulted from the backward revolution of the 
anterior part of the head, a transformation that actually takes place 
in the growth of the embryo. 

We may conclude, without going farther into matters of contro- 
versy, that the immediate ancestors of the arthropods possessed a 



26 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

long, segmented body, at the anterior end of which was a specialized 
cephalic region, differing from the annelid head in that it comprised 
both the prostomium and the first two or three primitive body seg- 
ments. In this early arthropod head, or protocephalon, the prostomium 
was still an important element ; it perhaps carried the ocular organs, 
though tentacles were probably lacking, and it was extended dorsally 
on the facial aspect of the head between the bases of the antennae ; 
on its ventral part, just before the mouth, there was a median lobe, 
the labrum. The first true head segment was much reduced, and its 
appendages were vestigial, or absent, unless they are represented in the 
eye-stalks of modern Crustacea. The second head segment bore the 
antennae, simple, jointed appendages, which acquired a preoral position 
on the sides or front of the head by a secondary forward migration 
of their bases. These two segments and the prostomium became in- 
timately fused, and in the ontogenetic development of present-day 
arthropods they appear as a unified, bilobed cephalic enlargement of 
the young embryo (figs. 8, 13, 16 A, B, C, 22 C, D, Pre). The brain 
at this stage was a syncerebrum, consisting of the archicerebrum and 
optic lobes fused with the ganglia of the preantennal and antennal 
segments, the two lateral nerve masses being united above the stomo- 
deum (fig. 15 B). The third postoral segment was probably more 
or less closely associated with the second, but, judging from embryonic 
evidence (fig. 8D), it did not at first form an integral part of the 
protocephalon. Its ganglia (later the tritocerebral lobes of the brain) 
at this stage constituted the first ganglia of the ventral nerve cord. 

There can be no question that the arthropods are to be divided into 
two principal groups, one represented by the modern mandibulate 
forms, the other by those in which the appendages of the fourth seg- 
ment retained the more generalized structure of the pedipalps of 
modern arachnids and xiphosurans. The separation of the two groups 
must have taken place in the protocephalon stage, for, as will later 
be shown, the unity of structure in the mandibles of all the mandibu- 
late forms is such as to leave no doubt that the mandible is a common 
inheritance from a primitive mandibulate ancestor. But, before the 
definitive gnathal segments were added to the head, it would seem 
that the postantennal, or tritocerebral, appendages must have as- 
sumed the principal gnathal function by means of basal endites that 
served as masticatory lobes. In the xiphosurans and arachnids, these 
appendages have become the chelicerae, if modern embryology is 
rightly interpreted ; in the crustaceans they lost their gnathal function 
and were developed into the second antennae ; in the land-inhabiting 



NO. 3 INSECT HEAD — SNODGRASS 2J 

niyriapods and insects they have become reduced to rudiments, or 
to embryonic vestiges. 

Insects were thoroughly modern in the later part of the Carbon- 
iferous period, when their remains are first known from the geological 
records. They must have been in the course of evolution during all 
the preceding extent of the Paleozoic era. Scorpions are found in 
the Silurian rocks, eurypterids in the Ordovician. Crustaceans, as 
represented by trilobites and other forms, were well developed in the 
Cambrian. The common arthropod ancestors in the protocephalic 
stage, long antedating the divergence of the several modern groups, 
must have existed, therefore, in remote ages of Pre-Cambrian time. 

THE DEFINITIVE ARTHROPOD HEAD 

In all modern arthropods, at least one pair, and usually several 
pairs of the segmental appendages following the protocephalon are 
modified to form organs of feeding, and they are crowded forward 
toward the mouth, those of the first pair coming to lie at the sides 
of the mouth opening. These appendages become the " mouth parts " 
of insects, and in general they may be termed the gnathal appendages. 
As a consequence of the forward transposition of the gnathal appen- 
dages, the postoral, sternal parts of the protocephalic segments are 
reduced and in most cases practically obliterated, their places being 
taken by the sterna of the gnathal segments. Early in the course of 
evolution, therefore, the gnathal segments themselves must have had 
a tendency to fuse with the protocephalon to form an enlarged head 
region ; and nearly all the arthropods show in some degree the results 
of this tendency toward a more extensive cephalization of the anterior 
segments in the formation of a composite definitive head. 

The condensation of the anterior segments has resulted in the for- 
mation of a definite cephalic structure in many of the arthropod 
groups. Among the Crustacea, however, there is much variation in 
the composition of the head. In the decapods, the protocephalon alone 
forms a distinct though immovable head piece — it is that part attached 
within the anterior end of the carapace, overhung by the rostrum, that 
bears the eyes, the antennules, the antennae, and the labrum, and 
which may be easily detached from the region covered by the cara- 
pace (fig. i/B). The segments of the mandibles, the maxillae, the 
maxillipeds, and the legs are united dorsally in the wall of the cara- 
pace. The jaws of the decapods, therefore, are not attached to the 
primitive head, and though the protocephalon and carapace may be 
said to constitute a " cephalothorax," there appears to be no reason 



28 



SMITHSONIAN MlSCliLLANEOUS COLLECTIONS 



\OL. 81 



for regarding the region of the carapace formed of the gnathal seg- 
ments as a part of the head, since there is no evidence that the decapod 
head ever included more than the protocephalon. 

The generaUzed malacostracan crustacean, Anaspides, also retains 
the protocephalon as an independent head piece attached within the 
projecting anterior rim of the mandibular segment. The large mandib- 
ular segment is likewise free from the following maxillary segment, 
but the two maxillary segments and the first maxilliped segment are 




Fig. 16. — Four stages in the development of Forficula. (From Heymons, 1895.) 

A, embryo differentiated into a protocephalic head, and a body. B, appendages 
of gnathal segments (Md, iMx, 2M.r) well developed. C, the gnathocephalic 
region (Cnc) compact, but still distinct from protocephalic region. D, proto- 
cephalic and gnathocephalic' regions united in the definitive head (H). 

Ab, abdomen; Ajii, amnion; Ant, antenna; Clio, chorion; Gnc, gnatho- 
cephalon ; H, definitive head ; Li, first leg ; Lin, labrum ; Md, mandible ; iMx, first 
maxilla; J>71/.r, second maxilla; Pre, protocephalon; Set, serosa; Th, thorax. 

fused into a composite region bearing the maxillae and the first 
maxillipeds. 

In most of the other Crustacea, the head either is a unified cephalic 
structure consisting of the protocephalon and the three gnathal seg- 
ments, in some forms with one or two of the maxilliped segments 
added, or it exhibits varying stages in the condensation of the gnathal 
and maxilliped segments with the protocephalon. A relatively primi- 
tive condition is shown by Eiihranchipus (Anostraca), in which the 
protocephalon itself is a distinct and well-developed head capsule (fig. 
17 A, Pre) carrying the first and second antennae (lAiif, 2Ant), the 



NO. 3 INSECT IIKAD SNODGRASS 29 

eyes (£). and the laliruni (Lin) ; but to it is attached the tergum of 
the mandibular segment (I\ ) bearing the large, jaw-like mandibles 
(Md). Following the mandibular segment, comes the region of the 
two maxillar}' segments (V + VI) with the rudimentary first and 
second maxillae on its under surface. Euhranchiptis thus re|)resents a 
stage in the evolution of the head almost equivalent to that in the em- 
bryonic development of insects shown in figure i6 C where the gnathal 
segments {Gnc), in process of being united with the protocephalon 
(Pre), still constitute a distinct body region. In Limnaclia (Choncos- 
traca), the structure of the head is essentially as in Euhranchipus, but 
the gnathal segments are more intimately united with the proto- 
cephalon, and the second antennae are typical biramous appendages. 

In A pus (Notostraca) the head is more highly evolved (fig. 17 D. 
E), and its lateral and posterior margins are produced into a large 
cephalic carapace (Cp). The protocephalon and the gnathal segments 
are imited, but their respective areas are well defined dorsally (D). 
The protocephalon (Pre) is set ofif from the mandibular tergum (IV) 
by a sinuous transverse groove (x) ; on its upj^er surface it bears 
the group of head sense organs, including the compound eyes (E) , 
and, on its lower surface (E), the antennae (Ant) and the labrum 
(Lin). The tergal region of the mandibular segment (D, /F^) is dis- 
tinctly limited posteriorly by a second suture ( \' ) on the dorsal sur- 
face of the carapace, behind which is a narrow area representing the 
dorsal wall of the two maxillary segments (['" + VI), from the pos- 
terior edge of which is reflected the median part of the carapace. 
Back of the head, and partly covered by the carapace, is the long, 
flexible body of forty or more segments. Here is a condition f|uite 
different, therefore, from that of the decapods (fig. 17B. C), in 
which latter the protocephalon has retained its individuality, while 
the gnathal segments have united with those of the maxillipeds and 
the ambulatory limbs to form the region of the carapace (C, Cp). 

In the Amphipoda and the Isopoda, the head consists of the pro- 
tocephalon, the three gnathal segments, and one or two of the maxilli- 
ped segments. In these groups, however, the head segments are fused 
into a cranium-like capsule (figs. 17 F, H, 28 A), in which little nr no 
trace of the original head segmentation is to be discovered. In form 
and general appearance, the amphipod head (fig. 17 H) often cu- 
riously suggests the head of an insect, but both the amphipod and the 
isopod cranium appears to contain at least one more segment than is 
known to be included in either the insect or the myriapod head. 

The head in the Chilopoda (fig. 17 G), Diplopoda (K). and Hexa- 
poda (I), is a highly evolved cranial capsule composed of the protoce- 



30 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

phalon and the gnathal segments, but so thoroughly fused are all the 
cephalic elements that the segmental composition of the head is no 
longer discernible in the head wall. The insect head is a well-standard- 
ized structure, which, though varying greatly with regard to form, 
is the same in fundamental construction throughout all the insect 
orders. The myriapod head, likewise, exhibits no modifications in its 
basic structure, and, from a study of the head alone, it is impossible 
to judge whether the cephalic structures of the myriapods and of the 
insects has had a common origin, or whether in each group the head 
has been evolved along a separate line of development. Considering 
the dififerences in the head appendages, and especially in the mandibles, 
as will be shown later, it appears probable, however, that the myria- 
pods and insects are not as closely related as the form of the head 
might otherwise suggest. The insect head resembles also the head of 
the amphipods and isopods, as already pointed out, but it can be 
shown that the evolution of the head appendages has run parallel in 
the insects and the crustaceans, and here again, therefore, we must 
conclude that the similarities in the head structure are only equal 
results of the primary tendency toward a condensation of the gnathal 
segments with the protocephalon, in consequence of the drafting of 
the appendages of these segments into the service of the mouth. 

Considering all the evidence, especially that which will be adduced 
from a study of the mandibles, it seems most probable that the several 
principal arthropod groups represent independent lines of descent 
from ancestors differentiated at an early stage in the evolution of the 
composite head structure. The early development of the thorax in 
the insect embryo, before the gnathal segments are added to the head 
(fig. 13), is evidence that the insects formed a distinct arthropod 
group long before the completion of the definitive head, unless the 
differentiation of the thorax in the young insect embryo is to be re- 
garded as a precocious embryonic development, comparable with the 
early development of the head in the vertebrate embryo. It is scarcely 
necessary, however, to postulate, as suggested by Walton (1927), a 
separate origin of the insects from annelids. 

In the Arachnida, the protocephalon constitutes a distinct head at 
an early embryonic period, but, as shown in Balfour's illustration (fig. 
22 C, Pre), it does not include at this stage the tritocerebral segment 
(///) in its composition. At a later stage, however, the tritocerebral 
segment and the five following segments are usually added to the 
protocephalon to form a cephalothorax (fig. 17 J, CtJi). The appen- 
dages of the cephalothorax of an adult arachnid are the chelicerae 



Pre X r/ VA'I 




Fig. 17. — Head or head region of various arthropods. 

A. head and anterior body region of Eubranchipus vernalis (Phyllopoda, 
Anostraca), with gnathal segments (/F, V, VI) distinct from protocephalon. 
B, protocephalic head piece of Spironfocaris polaris (Decapoda) separated from 
the carapace. C, carapace of Spironfocaris polaris from which the proto- 
cephalon (B) has been detached. D, head and head carapace of Apus louf/i- 
candata (Phyllopoda, Concostraca ) , dorsal view, showing segments IV , V , VI 
added to protocephalon {Pre) and forming carapace. E, ventral view of 
.same. F, head of PorcclUo (Isopoda) with maxillae removed. G, head of 
Scntiqcra forceps (Chilopoda). H, head of Orchcstoidea calif ornica (Amphip- 
oda)." I, head of Machilis (apterygote insect). J, cephalothorax and anterior 
alxiominal segments of a scorpion (Arachnida). K, head of Eurynrus cryfhro- 
pygus ( Diplopoda ) . 

a, dorsal (or posterior) articulation of mandible; Ant. antenna; lAiit, first 
antenna; ^Ant, second antenna; c, anterior articulation of mandible; Ch, 
chelicera; Cp, carapace; Cth, cephalothorax ; E, compound eye; Gch. gnatho- 
chilarium; II', mandibular segment; iL, first leg; Lm, labrum; Md. mandible; 
tMx. first maxilla; jM.v, second maxilla; iMxp, first maxilliped ; MxPlp, 
maxillary palpus; Pdp. pedipalp ; Pre. protocephalon; iT , first tcrgum ; V, first 
maxillary segment; /7, second maxillary segment; x, suture between proto- 
cephalon and mandibular segment; y, suture between mandibular and first 
maxillary segments. 

3 31 



32 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

(Ch), or tritocerebral appendages, the pedipalps (Pdp), which are the 
mandibular appendages of other groups, and four pairs of legs (L), 
which are represented by the two maxillae and the first two pairs of 
maxillipeds in the Crustacea. Antennae are lacking in all adult arach- 
nids, but some writers (Croneberg, 1880, Jaworowski, 1891) have re- 
ported the presence of antennal rudiments in the embryos of certain 
species (fig. 22 B, Ant). The comparative lack of specialization in the 
arachnid limbs suggests that the Arachnida are an ancient group of 
arthropods having little direct relationship to other forms, except to the 
Xiphosura and possibly to the extinct eurypterids. In the Solpugida. 
the cephalothoracic region is divided into an anterior cephalic part 
carrying the eyes, the mouth, the chelicerae, the pedipalps, and the 
first pair of legs, and into a posterior thoracic |)art carrying the second, 
third, and fourth pairs of legs. The division between these two body 
parts, as compared with insects, falls between the first and second 
maxillary segments, and the parts, therefore, are in no way compar- 
able with the insect head and thorax. In the ticks (Ixodoidea), the 
head-like structure known as the capitulum is said to bear only the 
chelicerae and the pedipalps. In its composition it is thus equivalent 
to the protocephalon with only the first gnathal segment added. 

Cephalization in the Arthropoda, then, apparently has progressed 
from the prostomial stage (archicephalon) to the formation of a 
protocephalon, from a protocephalon to the usual definitive head, or 
telocephalon, and finally to the union of head and body regions in a 
cephalothorax. The archicephalic stage is to be inferred from the 
evident derivation of the arthropods from an annelid-like ancestor 
having the prostomium as the only defined head. The protocephalic 
stage is shown in the development of all arthropod embryos, and is 
retained in the decapods and related crustaceans, where the carapace 
is a gnatho-thoracic structure. The telocephalic stage exhibits a 
progressive evolution in phyllopods, amphipods, and isopods by the 
addition of one, two and three, four or five segments to the protoce- 
phalon ; in insects and myriapods it has reached a standardized con- 
dition in which the head is composed of six segments and the pro- 
stomium. The cephalothoracic stage is characteristic of the Xiphosura 
and Arachnida. in which the segments of all the fully developed 
appendages are united, and combined with the prostomium. 

A study of the head alone does not furnish a sufficient basis for a 
discussion of the inter-relationships of the various arthropod groui)s. 
but it must be recognized that the facts here given, and others to be 
descril)ed in this paper have an important bearing on the subject. 



NO. 3 INSECT HEAD ^SNODGRASS 33 

and that their signiticance has not been fully taken into account by 
those who have formulated theories of arthropod relationships and 
descent. 

II. GENERAL STRUCTURE OF THE INSECT HEAD 

The almost complete suppression of the primitive intersegmental 
lines in the insect head makes a study of the head segmentation in 
insects a difficult matter, and investigators differ widely in their 
views as to the parts of the adult head that have been derived from 
the several head segments. Since the prostomial region and the three 
segments of the protocephalon are never distinct, even in the earliest 
embryonic stages, it seems fruitless to speculate as to what areas of 
the adult cranium are to be attributed to them individually, but the 
general protocephalic region must be at least the region of the clypeus 
and frons, the compound eyes, and the antennae. In as much as the 
muscles of the three pairs of gnathal appendages have their origins in 
the posterior parts of the head, it is reasonable to assume that the 
areas upon which these muscles arise represent the walls of the gnathal 
segments that have been added to the protocephalon. 

According to Heymons (1895), who bases his conclusions on a 
study of the embryonic development of the head in Periplaneta and 
Anisolahis, the entire cranium except the frons and the region of 
the compound eyes and the antennae is formed from the walls of the 
mandibular, maxillary, and labial segments. Janet ( 1899) , taking the 
attachments of the muscles of the appendages on the head walls as 
criteria of the respective segmental limits, maps the cranium into 
areas that closely correspond with the segmental regions claimed by 
Heymons. From Riley (1904), on the other hand, we get a quite 
different conception of the definitive head structure. According to 
Riley's account of the development of the head of Blafta, the great 
cephalic lobes of the embryo form most of the adult head capsule. 
The dorsal and lateral walls of the gnathal segments, Riley says, are 
so reduced by the posterior growth of the cephalic lobes that little 
remains of them in the adult head — only the extreme posterior and 
postero-lateral parts of the cranial walls, and the postoral ventral region 
being refera1)le to them. This view must assume that the muscles of 
the gnathal segments have moved forward to the protocephalic region 
as their own segments became reduced, and it would nullify the evi- 
dence of head segmentation based on muscle attachments. The writer 
is inclined to agree with Heymons and Janet that the muscle attach- 
ments on the lateral and dorsal walls of the cranium should be pretty 
closelv indicative of the limits of the gnathal terga in the composition 



34 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

of the head, but it must be admitted that muscle bases can undergo 
rather extensive migrations. That the gnathal segments contribute a 
consideral)le part to the cranial walls of the definitive insect head is 
clearly suggested by Heymons' figures of the development of Forficula 
(fig. i6), and, as already shown, there can be no doubt that these 
segments enter bodily into the head composition of Crustacea that have 
a well-defined composite head. With insects, it is a question of the 
degree of reduction that the gnathal segments have suffered after their 
union with the protocephalon. 

By whatever phylogenetic course the cephalic region of the insect 
body has arrived at its definitive state, it acquired long ago a cranium- 
like form, and a definite structure that has since been modified only in 
superficial characters, adaptive to diflferent modes of living and to 
dififerent ways of feeding in the various groups of modern insects. 

THE HEAD CAPSULE 

The chitinous walls of the definitive head capsule constitute the 
epicranitiiii. In an adult insect head preserving the typical embryonic 
position, with the facial aspect directed forward (fig. i8B), the 
mouth parts are suspended from the ventro-lateral edges of the epi- 
cranium. A pair of compound eyes (E) typically have a lateral or 
dorso-lateral position, and three ocelli (O) occur between them on 
the dorsal or facial area of the head (A). The antennae (Ant) vary 
in their location from positions just alcove the bases of the mandibles 
(fig. 50 A, Aut) to a more median site on the dorsal part of the face 
(fig. 18 A. B). The top of the head, or vertex (fig. 18 A, B, J\\-). 
is marked by a median coronal suture (A, cs) that turns downward 
on the face and divides into the frontal sutures (fs). which diverge 
ventrally to the anterior articulations of the mandibles (c). The 
coronal suture and the frontal sutures together constitute the epi- 
cranial suture. The lines of these sutures are marked internally by 
ridges, and the coronal ridge is sometimes developed into a plate 
supporting muscle attachments. The median facial region between 
and below the frontal sutures is the frons (Fr). ventral to which is 
the clvpeus (Clp). with the iabruni (Liu) suspended from the lower 
margin of the latter. 

The posterior surface of the epicranium (fig. 18 C) is occupied 
by the opening (For) from the head cavity into the neck, usually a 
large aperture, properly termed the foramen magnum by analogy with 
vertebrate anatomy, but commonly called the " occipital foramen " 
by entomologists. The surface of the head surrounding the foramen 



NO. 3 



INSECT HEAD SNODGRASS 



35 



dorsally and laterally is the occipital area. Its anterior limit is de- 
fined in orthopteroid insects by the occipital suture (ocs). The occip- 
ital area is subdivided by a suture lying close to its posterior margin, 





Fig. i8. — Generalized structure of the head of an adult pterj-gote insect, 
diagrammatic. 

A, anterior view. B, lateral. C, posterior. D, ventral. 

a, posterior articulation of mandible ; Ant, antenna ; as, antennal suture ; 
at, anterior tentorial pit ; c, anterior articulation of mandible with cranium ; 
CIp, clypeus ; cs, coronal suture; Cv, neck (cervix); cv, cervical sclerite; 
E, compound eye ; c, articulation of maxilla with postgenal margin of cranium ; 
/, articulation of labium with postoccipital rim (Poc) of epicranium; For, 
foramen magnum ; Fr, f rons ; fs, frontal suture ; g, postoccipital condyle for 
articulation of first cervical sclerite with head ; Ge. gena ; Hphy, hypopharynx ; 
HS, suspensorium of hypopharynx; Lb, labium; Lin, labrum ; Md, mandible; 
MdC, opening in head wall where mandible removed; Mth, mouth; Mx, maxilla; 
MxC, opening in head wall where maxilla removed ; O, ocelli ; Oc, occiput ; os, 
ocular suture ; ocs, occipital suture ; Pyc, postgena ; Poc, postocciput ; pos, 
postoccipital suture ; pt, posterior tentorial pit ; sgs, subgenal suture ; SIO, 
orifice of salivary duct; Vx, vertex. 

here named the postoccipital suture (fig. i8 B, C, pos), which sets ofif a 
narrow marginal rim of the cranium, or postocciput {Poc), to which 
the neck membrane is directly attached. The postoccipital suture, 
though sometimes inconspicuous by reason of the reduction of the 



Mt, 



36 SMITHS()NIAi\ MJSCELLANEOUS COI.I.ECTIONS VOl,. 81 

postoccipital rim, is the iiKjst constant suture of the cranium. The 
dorsal part of the occipital area before it is termed the occiput (Oc), 
and the lateral ventral parts the postgenae {Pge). Rarely the occiput 
and the postgenae are separated, as in Mclanoplus, by a short suture 
on each side. 

The lateral areas of the cranium, between the occipital suture and 
the frontal sutures, and separated dorsally by the coronal suture, have 
been appropriately termed by Crampton (1921) the parietals. The 
parietal area behind and below the compound eye is the gena (fig. 
18 B, Ge), that between the eyes is the vertex. The lower marginal 
area of each lateral wall of the head is commonly marked by a sub- 
marginal suture (fig. 18 A, B, j-f/.?), which forms an internal ridge 
strengthening the ventral lateral edge of the cranium (fig. 39 A, 
SgR). The suture has been termed the '' mando-genal '* suture 
(Yuasa, 1920, MacGillivray, 1923), but, for grammatical reasons, 
the writer would substitute the term subgcnal suture, and call the 
corresponding ridge the siibgenal ridge. The ridge is sometimes known 
as the " pleurostoma." When an epistomal ridge separates the clypeus 
from the frons, it unites the anterior ends of the subgenal ridges. 

The true ventral wall of the head is the region between the bases of 
the mouth parts (fig. 18 D), the median area of which is produced 
into the variously modified lobe known as the liypo pharynx (Hphy). 
Anterior to the base of the hypopharynx, and immediately behind the 
posterior, or epipharyngeal, surface of the lal:)rum and clypeus is the 
moutli {Mth). The space inclosed by the labrum and the mouth 
parts is often called the " mouth cavity," but, since it lies entirely 
outside the body, it is more properly a preoral cavitv. 

The frons, clypeus, and labrum belong to the prostomial region of 
the head. The frons and clypeus are not always distinct, but when they 
are separated, the dividing fronto-clypeal groove, or epistomal suture 
(fig. 18 A, B, c.?), extends typically between the bases of the man- 
dibles. That the more primitive division of the prostomium, however, 
is that between the labrum and the clypeal area is evidenced by the 
fact that the labral retractor muscles always extend from the base of 
the laljrum to the frontal area (fig. 19, 2, 5). The clypeus, on the 
other hand, can not be regarded as a mere articular region between 
the labrum and the frons, secondarily developed into a chitinous plate, 
as some writers have suggested, because the most anterior of the 
dilator muscles of the stomodeum have their origins upon its inner 
surface (fig. 41, jj, 34). The external suture separating the clypeus 
from the frons appears to be incidental to the development of an 
internal epistomal ridge (fig. 39 A, B, C, iii?) forming a brace be- 



NO. 3 INSECT HEAD- SNODGUASS 37 

tweeu the anterior articulations of the mandibles. The typical position 
of the fronto-clypeal suture is on a line l)et\veen the mandibular bases 
passing- through the roots of the anterior arms of the tentorium; but 
the suture and its ridge are often arched upward, as in the Hymen- 
optera, Psocidae, and Homoi^tera (fig. 46 E, F, G, H), or bent 
dorsally in an acute angle, as in the caterpillars (fig. 50 A). The 
fronto-clypeal suture is to be identified by the origin of the anterior 
arms of the tentorium from its internal ridge ; the frontal region 
above it is marked by the attachments of the labral retractor muscles, 
and the clypeal region below is distinguished by the origins of the first 
anterior stomodeal muscles on its inner surface. The value of these 
characters wall be illustrated in succeeding parts of this paper. The 
clypeus may be secondarily divided into an anteclypcus and a postcly- 
peus, the latter sometimes attaining a special development, as in 
Homoptera. 

If the prostomial region of the adult head embraces only the labrum, 
clypeus, and frons, the frontal sutures must separate the prostomial 
area from the area derived from the segmental elements of the head, 
as maintained by Riley (1904) ; but, if the compound eyes and the 
optic lobes of the brain had also a prostomial origin, as claimed by 
Heymons (1895, 1901), then an area between and including the com- 
pound eyes must be regarded as a part of the general prostomial 
region. Following Heymons' interpretation, Berlese (1909) recog- 
nizes a " postf rons " embracing the ocular region, and a " pref rons," 
which is the ordinary frontal sclerite. Whatever the facts of the case 
may be, it will be most convenient to retain the name " frons " for 
the latter sclerite. In general, the frontal sutures mark the lines of 
cleavage in the facial cuticula at the time of a molt, but there are 
exceptions to this rule, for the cuticular splits, when extended from 
the end of the coronal suture, may diverge to the sides of the frons, 
and may even extend laterad of the bases of the antennae, as in 
Odonata (fig. 46 I). 

The frontal sutures are often obscured or are lacking, and the frons 
then becomes confluent with the lateral epicranial walls. The anterior 
median ocellus, when present, is located upon the frons, or on the 
frontal region ; the paired ocelli usually lie above or posterior to the 
upper ends of the frontal sutures, though in some cases they appear to 
be in the sutures. The antennae are usually situated on the facial 
aspect of the head, but they never truly arise upon the frons. In 
post-embryonic stages, the antennae occupy positions varying from 
points just above the mandibles, as in caterpillars, to points laterad of 
the upper end of the frons ; they sometimes lie against the frontal 



J 
I 



38 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 81 

sutures, and by an approximation of their bases, they may constrict 
the f rons between them. The reversed relative position of the antennae 
and the compound eyes, as between embryonic and adult stages, comes 
about through the posterior revolution of the ocular region and the 
forward migration of the antennae. The antennal socket is generally 
strengthened by an internal circular ridge on the cranial wall sur- 
rounding it (fig. 39 A, AR), and the compound eye is likewise en- 
circled by an inflection of the cuticula close to its base (OR). These 
ridges and their external sutures set off the so-called ocular and 
antennal sclerites (fig. iSA, B). 

The posterior, or occipital, surface of the epicranium (fig. i8 C) 
is usually but a narrow area surrounding the foramen magnum (For) 
dorsally and laterally, the foramen Iieing normally completed ven- 
trally by the base of the labium (Lb), or by the neck membrane in 
which the labium is suspended. When the foramen is small, however, 
the occipital area often becomes a wide transverse surface on the back 
of the head, and its ventral, or postgenal, parts may form median 
processes that sometimes unite into a bridge beneath the foramen, in 
which case the latter becomes entirely surrounded by chitinous walls 
(fig. 48 B, C). The occipital suture (fig. i8 B, C, ocs), when present, 
is generally located a])out where the dorsal and lateral areas of the 
head wall are reflected upon the posterior surface. It does not seem 
probable that the occipital suture is a primitive intersegmental line of 
the head, for, though it lies approximately between the mandibular 
and maxillary regions, it does not consistently separate the bases of 
the mandibular and maxillary muscles, and the posterior articulation 
of the mandible is with the postgena posterior to the lower end of the 
suture (fig. i8 B, a). As is the case with most of the skeletal grooves, 
it is pro])able that the occipital suture has no significance in itself, and 
that it is merely incidental to its corresponding internal ridge, which 
strengthens the posterior part of the cranium along the line where 
the dorsal and lateral areas are reflected into the posterior surface. 

In the Machilidae the posterior part of the epicranium is crossed by 
a prominent suture lying close behind the eyes dorsally (fig. 17 I, 3') 
and extending" downward on each side of the head to a point on 
the lateral margin of the cranium between the base of the mandible 
(Md) and the base of the maxilla (Mx). This suture, therefore, ap- 
pears to separate the region of the mandibular segment from that of 
the maxillary segment in the cranial wall, and if it does so, it may be 
the homologue of the mandibulo-maxillary suture in the phyllopod 
crustaceans (fig. 17 A, D, y), and of the corresppnding suture in the 
more generalized malacostracan forms, such as Anaspides. Crampton 



NO. 3 INSECT HEAD SNODGRASS 39 

(1928a) has called the mandibulo-maxillary suture the " archice- 
phalic " suture, since he calls the region before it the " archicephalon," 
but the term thus applied denotes too much antiquity for a stage that 
is clearly subsequent to several others in the head evolution. A simi- 
larly-placed suture is present in the head of Japyx (fig. 30 B, PcR), 
but the relation of the suture here to the bases of the head appendages 
can not be determined. The occipital suture of the pterygote insect 
head, ending laterally before the posterior mandibular articulations, 
therefore, is probably not the mandibulo-maxillary suture of the 
simpler crustaceans, or the homologue of the posterior suture in the 
head of Machilis. 

The postoccipital suture (fig. i8B,C, pos) is a most important 
landmark of the head because it is invariably present, and because of 
its constant anatomical relations to other parts. The posterior tentorial 
pits (pt) are always located in its lower ends, and if the pits migrate 
in position, as in some of the Coleoptera and other insects, the lower 
ends of the suture are correspondingly lengthened (fig. 49 C, pt, pt) . 
Frequently the suture is inconspicuous by reason of its closeness to 
the margin of the cranium, and for this reason, probably, it has not 
been given sufficient attention by entomologists. Comstock and Kochi 
(1902) believed that the suture is the groove between the pleurites 
of the maxillary segment; but Riley (1904) claimed, from a study of 
the developing head of Blatta, that the suture is the intersegmental 
groove between the maxillary and the labial segments, and that the 
postoccipital sclerite is a remnant of the wall of the labial segment, 
which segment is otherwise obliterated or represented in the anterior 
part of the neck membrane. This view is at least in harmony with 
certain anatomical relations in the adult head, and is tentatively 
adopted in this paper. 

Internally, the postoccipital suture forms a postoccipital ridge (fig. 
39 A, PoR) just within the foramen magnum, and upon this ridge are 
attached the anterior ends of the dorsal muscles of the prothorax 
(figs. 45 A, 57A, B, C). The ridge, therefore, must be a primary 
intersegmental fold corresponding with the ridges or phragmata sup- 
porting the longitudinal muscles in the thorax and abdomen. If it 
does not represent the fold between the maxillary and labial segments, 
it should be that between the labial segment and the prothorax. If 
the first possibility is true, as claimed by Riley, there is an interseg- 
mental line lost somewhere in the neck, and the muscles going from 
the first phragma of the thorax to the postoccipital ridge of the head 
must be regarded as extending through the region of two primary 
segments. If, on the other hand, the posterior ridge of the head is the 



40 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

intersegmental fold between the labial and the prothoracic segments, 
the muscles in the neck are all muscles of the prothorax, and the neck 
itself is prothoracic. It is evident that nuicli mori)hological significance 
hinges on this problem. The neck sclerites, for example, in the first 
case, might belong either to the labial segment or to the prothorax, 
or to both ; in the second case, they could pertain only to the prothorax. 
The relation of the posterior arms of the tentorium to the postoccipital 
suture and ridge will be noted under the special description of the 
tentorium (page 50). 

The labrum, the appendages of the gnathal segments, and the 
hypopharynx constitute the mouth parts of insects. The gnathal 
appendages are the mandibles, the first maxillae, and the second 
maxillae, which last are united in insects to form a labium. The 
morphology of these appendages will be discussed in a later section 
(pages 79-90), but it is important here to understand their relations 
to the cranial wall. The mandible in biting pterygote insects is typi- 
cally suspended from the lower edge of the gena and postgena, and 
swings outward and inward on a longitudinal axis between anterior 
and posterior articulations with the head wall. The anterior articu- 
lation is with a condyle at the contingent angles of the gena and 
clypeus (fig. 18 A, B, D, c), the posterior with a shallow facet on the 
lower margin of the postgena (B, D, a). 

The maxilla hangs from the lower edge of the postgena, upon 
which it is freely movable by a single articular point just before the 
lower end of the postoccipital suture (fig. 18B, D, g). The labium, 
in generalized insects, is suspended from the neck membrane, but each 
lateral angle of its transverse base is closely attached to the postoc- 
cipital rim of the head (B, C, D, /). The positions of the maxillary 
and labial articulations relative to the postoccipital suture (pos) are 
in harmony with the idea that this suture is the intersegmental groove 
between the maxillary and the labial segments. In some insects, the 
labium is shifted forward between the ventral edges of the postgenae, 
and thus becomes removed from its primitive position. In such cases, 
as in caterpillars (fig. 53 A) and adult Hymenoptera (fig. 48 B, C), 
the ventral angles of the postgenae may approach each other medially, 
or even unite into a ventral bridge (hypostoma) behind the labium. 
In other insects, in which the posterior part of the head is lengthened, 
the base of the labium is elongated between the postgenae, forming the 
]>late known as the gula. These modifications, however, will be dis- 
cussed more fully in section VI of this paper. 

The head is attached to the thorax by a cylindrical, membranous 
neck, or cervix (fig. 18 B. Cv). In each lateral wall of the neck there 



NO. 3 INSECT HEM) SNODGKASS 4I 

is typically a pair of lateral neck plates, or cervical sclerites, hinged 
to each other. The first is articulated anteriorly to a small process, 
the odontoidea (Yuasa, 1920), or the occipital condyle (Crampton, 
1921), on the rear margin of the postoccipital rim of the head 
(B, C, g) just above the base of the labium. The posterior neck plate 
articulates with the anterior margin of the prothoracic episternum. 
Other cervical sclerites of less constant form are sometimes present in 
the ventral wall of the neck, and occasionally there are chitinizations 
also in the dorsal wall. The lateral neck sclerites are important ele- 
ments in the mechanism for moving the head on the thorax. Upon 
them are inserted muscles from the postoccipital ridge of the head, 
and from the inner surface of the prothoracic tergum (fig. 45 A, B). 
The uncertainty of the morphology of the insect neck, and con- 
sequently of the neck skeleton, furnishes a problem still to be solved. 
As already pointed out, the status of the neck and of its sclerites 
will depend upon that of the postoccipital rim of the head : if the 
latter is an anterior remnant of the labial segment, the neck sclerites 
may belong to the labial segment, or also to the prothorax ; if , however, 
the postoccipital ridge of the head, upon which the anterior ends of the 
dorsal prothoracic muscles are attached, is the infolding between the 
head and the prothorax, then the neck can only be a part of the pro- 
thorax. The second assumption looks improbable in view of the 
position of the labial articulations in generalized insects (fig. 18 B/). 

THE LABRUM AND EPIPHARYNX 

The labrum is a characteristic feature of the arthropod head, and 
probably corresponds with the tip of the annelid prostomium. In the 
embryo (figs. 8 D, 13, 22 A, D, Lrii), it appears at an early stage as 
a median ventral lobe of the prostomial region, lying just before the 
point where the stomodeal invagination will be formed. In the mature 
head the mouth opening (figs. 18 D, ig, Mth) is immediately behind 
the base of the labrum (Lm), and the posterior, or epipharyngeal, 
surface of the latter is continued directly into the dorsal wall of the 
pharynx (fig. 19, Phy). The adult labrum takes on various forms 
in different insects, but it is typically a broad flap freely suspended 
from the lower edge of the clypeus (fig. 18 A, Lin). When movable, 
the labrum is provided with muscles inserted on its base, having their 
origin on the inner surface of the frons. Typically, there are two 
pairs of these muscles, one pair (fig. 19, 2) inserted anteriorly on 
the labral base, the other (j) posteriorly on the chitinous bars of the 
inner face of the labrum known as the tormae (figs. 37 B, 42 A). 



42 SMITHSONIAN MISCELLANEOUS COLLECTIONS \0L. 8 1 

The points of origin of the lahral muscles serve to identify the frontal 
sclerite, or the true frontal region when the frontal sutures are lack- 
ing. Frequently there is only one pair of lahral muscles (fig. 50 E, 
G), and when the labrum is immovable on the clypeus, both pairs 
are lacking. The labro-frontal muscles are to be regarded as median 
muscles of the prostomium. On the posterior surface of the labrum 
there is often a median lobe, the cpipharynx (fig. 19 EpJiy), that fits 
between the bases of the closed mandibles, and obstructs the entrance 
to the mouth (Mth) when the labrum is closed upon the hypopharynx. 

THE STOM ODEUM 

In the embryonic development of arthropods, the endodermal part 
of the alimentary canal, which becomes the true stomach, is formed 
within the body and has at first no opening to the exterior. The an- 
terior and the posterior ectodermal parts, or stomodeiim and procto- 
deum, of the definitive alimentary tube are ingrowths of the ectoderm 
at the two extremities of the blastopore. Their inner ends abut 
against the ends of the endodermal sac, and their final union with 
the latter takes place by an absorption of the adjacent walls. In some 
insects the proctodeum does not open into the ventriculus until the 
end of the larval stage. 

If the ontogenetic development of the alimentary canal is to be 
translated literally into phylogenetic evolution, we should have to 
believe that the arthropod stomach was once a closed sac, and that the 
stomodeum and proctodeum are secondary means of communication 
with it. But, if insects have had a continuous line of free-living 
ancestors, this seems unlikely, and it is more probable that, in their 
actual history, the stomodeum and the proctodeum have been formed 
as open invagination of the primitive circumoral and circumanal 
regions, and that the discontinuous development of the three parts of 
the alimentary canal in ontogeny is an adaptation to embryonic or 
larval conditions. 

It has been proposed by Janet (1899, 1911) that the stomodeum 
consists of the walls of three primitive segments that once formed 
the true anterior end of the body, but which have been inverted, as the 
primitive mouth, now the orifice from the stomodeum into the stomach, 
was retracted. This theory would give a plausible explanation of the 
presence of the stomodeal ganglia, but it must assume that these 
ganglia have been formed from paired ventral rudiments which have 
migrated dorsally and fused on the upper surface of the stomodeum. 
The known origin of these ganglia from the epithelium of the dorsal 



NO. 3 



INSECT HEAD — SNODGRASS 



43 



wall of the stomodeum, however, is direct evidence that they do not 
belong to the system of the ventral nerve cord. 

The stomodeum (fig. 19) is usually differentiated into several parts 
in the mature insect, which may include a buccal cavity (BuC), a 
pharynx (Pliy), an oesophagus (OE), a crop {Cr), and a proven- 
trkulus {Pvent). The entire length of the tube, except the extreme 
anterior end, is surrounded by circular and longitudinal muscles. In 
general the circular muscles form an external layer, the longitudinals 
an internal layer, but the arrangement and relative development of 



Vx Oc Poc Cv ,T, 



Ao 



Cr Pvent \ent- 



FrGne - 




PrC Epby Hphy 

Fig. 19. — The stomodeum of an insect, and its relation to associated organs 
in the head, diagrammatic. 

Ao, aorta; Br, brain; BnC, buccal cavity; Clp, clypeus ; Cr, crop; Ephy, 
epipharynx ; es, epistomal suture; Fr, frons; FrGng, frontal ganglion; Hphy, 
hypopharynx; Lb, labium; Liii, labrum ; LNv, lateral stomodeal nerve; Mth, 
mouth ; Oc, occiput ; CE, oesophagus ; Pliy, pharynx ; Poc, Postocciput ; PoR, 
postoccipital ridge ; PrC, preoral cavity ; Pvent, proventriculus ; SID, salivary 
duct ; SIO, orifice of salivary duct ; Ti, tergum of prothorax ; Tent, body of 
tentorium ; Vent, ventriculus ; J '.1% vertex ; 2, anterior labral muscle ; j, posterior 
labral muscle ; 3S, retractor muscle of the mouth angle. 

the two layers varies much in different insects, as will be illustrated 
in the grasshopper and the caterpillar (pages i [5 and 145). The buccal 
cavity, the pharynx, the oesophagus, and the crop are provided with 
dilator, or '' suspensory " muscles arising on the walls of the head, 
on the tentorium, and on the walls of the thorax (figs. 41, 44, 55)- 

The parts of the stomodeum can not be concisely defined, because 
they are functional adaptations of structure varying in different in- 
sects, rather than strictly morphological regions of the stomodeal tube. 
The buccal cavity is the anterior, or ventral, end of the stomodeum, in- 
cluding the region of the mouth opening (fig. 19, BuC). The dilator 
muscles of the stomodeum that have their insertion on the dorsal wall 



44 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

of the buccal cavity arise upon the clypeus, and this relation between 
the region of the buccal cavity and the clypeus appears to be a constant 
one. In the cicada, the sucking ]5ump is a mouth structure quite 
distinct from the true pharynx, and the origin of its dilator muscles 
upon the large striated facial sclerite of the head wall helps to identify 
this plate as the clypeus (fig. 46 H, Clp). In many insects, however, 
there is no structural distinction between the region of the buccal 
cavity and that of the pharynx. The retractor muscles of the mouth 
angles (fig. 19, ^8) have their origin on the inner surface of the frons, 
and their points of attachment give another character, in addition to 
that furnished by the labral muscles, for the determination of the 
frons when the limits of this sclerite are obscured, or the identity of 
the plate otherwise doubtful. The mouth retractors are inserted upon 
chitinous processes that extend into the stomodeal walls at the mouth 
angles from the suspensorial rods of the hypopharynx (fig. 42 B, y). 
Usually these processes are short and inconspicuous, but in the bees 
they form long arms united at their bases in a chitinous plate in the 
floor of the buccal cavity. 

The region of the pharynx is usually marked by a dilation of the 
stomodeum, and sometimes it forms an abrupt enlargement of the 
tube. The frontal ganglion is situated on its dorsal wall (fig. 19, 
FrGiig), and the circumoesophageal connectives lie at its sides. The 
dorsal dilator muscles of the pharynx have their origin on the frons, on 
the parietals, on the dorsal arms of the tentorium, and rarely one or two 
l^airs may encroach on the area of the clypeus (caterpillars). The 
pharynx of the Orthoptera is divided into an " anterior pharynx " and 
a "posterior pharynx" (Eidmann, 1925), but the part called the 
posterior pharynx, the dorsal dilator muscles of which arise on the 
posterior dorsal walls of the head, appears to correspond with the 
oesophageal region in some other insects. 

The oesophagus, when there is a distinct oesophageal region, is a 
narrow tubular part of the stomodeum following the pharynx (fig. 
19, OE). and varies much in length in dififerent insects. Its posterior 
end enlarges into the crop (Cr), or the crop is sometimes a lateral 
diverticuhun. The terminal part of the stomodeum in biting insects 
is usually a well-defined proventriculus (Pveiit). The chitinous 
intima of all parts of the stomodeum may be provided with short hairs, 
spicules, or chitinous nodules, but the inner cuticular structures are 
best developed in the proventriculus. where they generally have the 
form of longitudinal ridges or ])lates, with deep grooves between 
them. 



NO. 3 INSECT HEAD SNODGRASS 45 

According to the views of the earlier students of the digestive organs 
of insects, the proventriculus constituted a gizzard ; its inner chitinous 
fold, and its sheath of strong muscle fibers, it was pointed out, must 
serve to break up the larger or harder pieces of the food material not 
sufficiently crushed by the jaws. Experimental evidence of this 
function, however, is lacking, and Plateau (1874, 1876) argued that 
the proventriculus is merely an apparatus for passing the food from 
the crop into the stomach. More recently, Ramme (1913) has shown 
that the proventriculus, in Orthoptera and Coleoptera at least, has 
another important function in that the furrows between its chitinous 
ridges serve to conduct the digestive secretions of the ventriculus into 
the crop, where they attack the food material in advance of its en- 
trance into the stomach. The channels between the proventricular 
folds, then, rather than the folds themselves, are to be regarded as 
having the primary functional importance. Otherwise, the proven- 
triculus serves to conduct the food mass into the ventriculus. In 
Dytiscus, according to Ramme, the armature of the proventriculus 
retains the indigestible ]iarts of the food, which are later ejected 
from the mouth ; but in Orthoptera all the food matter passes through 
the alimentary canal. 

THE HYPOPHARYNX 

When the gnathal segments are added to the protoce])halun during 
embryonic growth, their sternal parts lose their identities in the gen- 
eral postoral ventral wall of the definitive head. On this region there 
is developed a median lobe between the bases of the mouth parts 
known as the hypopharyux (fig. 18 D, Hphy). The name is poorly 
chosen, because the organ in question lies on an exterior surface of the 
head entirely outside the pharynx, but it is a heritage of earlier days 
in entomology and is now w^ell established in entomological ter- 
minology. 

There is a diilerence of opinion among embryologists as to how 
many of the gnathal sterna contribute to the formation of the hypo- 
pharynx. According to Heymons (1901), the hypopharynx is formed 
in insects on the sternal region of the mandibular and first maxillary 
segments, but in the chilopods it arises on the mandibular segment 
alone. The fusion of the bases of the second maxillae in insects, and 
the similar union of both pairs of maxillary appendages in the chilo- 
pods gives reasons for this view, but, as will be shown ]M-esently, the 
primitive adductor muscles of all the gnathal appendages have their 
origin on the hypopharyngeal region in the chilopods and in the 
aptervgote insects — a condition which indicates that at least some part 



46 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOL. 8 1 



of each gnathal sternum enters into the hypopharyngeal region. Riley 
(1904) descrilies the hypopharynx of Blatclla germanica as formed 
in the embryo from the sterna of the mandibular, first maxillary, and 
second maxillary segments. 

In the more generalized pterygote insects, the hypopharynx hangs 
like a tongue in the preoral cavity (fig. 19, Hphy) behind the mouth 
(Mtli), shut in anteriorly by the labrum, laterally by the mandibles 
and maxillae, and posteriorly by the labium. Its base generally extends 
posteriorly to the labium (figs. 18 D, 19), and in the groove between 

Mth 

-4 




Lin Slin 

Fig. 20. — The hypopharynx. 

A, three-lobed hypopharynx of an ephemerid nymph, with ventral adductor 
muscles of mandibles (KLh) attached to its base. B, head of embryo of Amirida 
maritima (from Folsom, 1900), ventral view, showing median lingua (Lin) 
and paired superlinguae {Sliii) that combine to form hypopharynx of adult. 
C, transverse section through mandibles of embryo of Tomocerus plmnbcns 
(from Hoffman, 1911), showing origin of superlinguae (Slin) from inner 
angles of mandibles. D, hypopharynx of Microccntrum rhoinbifolmiii, ventral, 
with rudiments of suspensorial arms (HS) on which ventral mandibular ad- 
ductors (KLh) are attached. 

the two organs is situated the orifice of the salivary duct [SLO) . In 
general, therefore, the salivary orifice serves as a landmark for sep- 
arating the hypopharynx from the labium, or for determining the 
hypopharyngeal region when a specific hypopharyngeal lobe is lacking, 
as in the honeybee ; but the opening of the salivary duct may be at the 
apex of the hypopharynx, as in Homoptera, or, when the hypopharynx 
and labium are united, as in many insect larvae (fig. 54 A, D), it may 
lie at the tip of the combined labio-hypopharyngeal structure. 

In some insects the hypopharynx consists of a median part and of 
two lateral lobes. In such cases it usually projects forward like a lower 



M 



NO. 3 INSECT IIEAID SNODGRASS 47 

lip beneath the mouth opening. The lateral lobes are best developed 
in the more generalized insects, both apterygote (fig. 21 D. Ilphy) 
and pterygote (fig. 20 A), and in coleopteran larvae, but possible 
traces of them are to be found in many of the higher orders. The oc- 
currence of the hypopharyngeal lobes has been w^ell reviewed l)y 
Crampton (1921a) and by Evans (i92i),and those of lepidopteran 
larvae have been described by de Gryse (1915). The median lobe of 
the hypopharynx is best distinguished as the lingua, though some 
writers call it the " glossa " ; the lateral lobes have been termed " para- 
glossae " and " maxillulae," but Folsom (1900) has given them the 
more distinctive name of superlinguae, because the lateral lobes of the 
labium are commonly known as the paraglossae. 

The nature of the superlingual lobes of the hypopharynx has been 
much discussed. Hansen (1893) proposed that they represent the 
first maxillae, or maxillulae, of Crustacea, and Folsom (1900) be- 
lieved that their identity as such was established in the discovery of 
what he regarded as a corresponding pair of ganglia in the embryonic 
head of Anurida. Crampton (1921a), on the other hand, argued that 
the superlinguae of insects must be the homologues of the paragnatha 
of Crustacea, and it will be shown later in this paper that the identity 
in the relations of each of these organs to other structures of the head 
can leave little doubt of the truth of Crampton's contention. The super- 
linguae, then, are not the first maxillae of Crustacea ; but if the 
superlinguae represent a segment in the insect head, the paragnatha 
have a like significance in the crustacean head. It now appears prob- 
able, however, that neither of these organs has a segmental value, 
since Folsom's claim of the presence of a pair of superlingual ganglia 
has not been verified by subsequent research, and Hofifmann (1911) 
appears to have demonstrated that in the collembolan, Tomocerus 
plumheus, the superlinguae are derived during embryonic develop- 
ment from the inner basal angles of the mandibles (fig. 20 C, Slin) . 

In the Chilopoda and Diplopoda there is a single median hypo- 
pharyngeal lobe forming a projecting lip below the mouth opening 
(fig. 21 A, B, C, Hphy). In the Crustacea, the paragnaths usually 
lie to each side of the median line, and are associated with the first 
maxillae, but in some forms, as in Gammarus, they are united on a 
common median base, forming a bilobed structure very similar to the 
hypopharynx of the apterygote insect Japyx (fig. 21 D). 

The base of the hypopharynx is supported anteriorly, in generalized 
insects, by a pair of chitinous plates or bars that extend laterally at 
each side of the mouth, and form a suspensorial apparatus for the 



48 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8 1 

hypopharynx (fig. i8 D, HS). The plates appear to be chitinous 
remnants of the mandibular sternum. They are best developed in the 
myriapods. In Lifliobiiis (fig. 21 A). Scolopcndra (B). and Scutigcra 
(C), each plate is a large, irregular sclerite ( HS) attached laterally to 
the lower margin of the head wall at a point (d) before the base of the 
mandible, and ending mesally in the side of the hypopharynx. In some 
chilopods a process on the anterior free part of the mandible articu- 
lates against the hypopharyngeal plate of the same side. 

Attems (1926) describes the suspensorial plates of the hypo- 
pharynx in the chilopods as a mandibular support (" kommandibular 
Geriist "), but the homologous sclerites and their apodemal processes 
in the diplopods he calls the " tentorium." The writer has not ob- 
served corresponding structures in the Crustacea. In insects the 
hypopharyngeal supports are variously developed, but are usually 
reduced, and often rudimentary. In Machilis (fig. 21 E, HS) their 
outer ends are broadly fused with the basal angles of the clypeus 
iCIp) ; in Japyx ( D) the plates are reduced and united in a W-shaped 
sclerite in the base of the hypopharynx ; in Dissostcira (fig. 42 B, C, 
HS) they are slender bars extending outward to the bases of the 
adductor apodemes of the mandibles ; in Microcentrum (fig. 20 D, 
HS) they are rudimentary prongs diverging from the base of the 
hypopharynx. In many cases a process extends from each hypo- 
pharyngeal bar into the lateral walls of the mouth, where it supports 
the insertion of the retractor muscle of the mouth angle (figs. 42 B, 
44,^8), and may give rise to an extensive pharyngeal skeleton. In 
the bees these processes form the long rods bearing the protractor 
muscles of the pharynx, though the hypopharyngeal bars themselves 
are lacking. 

In the chilopods and in the apterygote insects, an apodemal process 
arises from the inner end of each suspensorial plate of the hypo- 
pharynx, and extends posteriorly below the sides of the pharynx (fig. 
21 A, C, D, HA). Upon these apodemes arise the retractor muscles 
of the hypopharynx, the ventral dilators of the pharynx, and ventral 
adductors of the mandibles, the first maxillae, and the second maxillae. 
These muscles are all properly sternal muscles, and their origin in the 
Chilopoda and Apterygota on the hypopharyngeal apodemes, which 
are sternal apophyses of the head, attests a primitive relation in these 
groups between the muscles of the gnathal appendages and the sternal 
parts of their segments. In some of the Crustacea, the corresponding 
muscles have their origins on a central endoskeletal structure that 
arises on the sternal region of the gnathal segments behind the mouth 
In many Crustacea, however, and in the Diplopoda, the ventral 



NO. 3 



INSECT IIEAI 



-SNODGRASS 



49 



muscles of the gnathal appendages, especially those of the mandibles, 
show a highly specialized condition in that they are mostly separated 
from their sternal connections and united upon a common transverse 




,-DT 



Fig. 21. — The hypopharyngeal apophyses and the tentorium. 

A, under surface of head of Lithobius, mandibles and maxillae removed, 
showing suspensorial plates (HS) of hypopharynx suspended from points (d) 
on margins of head, and hypopharyngeal apophyses (HA) invaginated from 
their inner ends and connected by ligamentous bridge (/) beneath pharynx. 

B, Head of Scolopcndra, ventral, maxillae and right half of cranium re- 
moved, showing attachment of mandibular adductors (KL, KL) on ligament 
uniting the hypopharyngeal apodemes. 

C, Sciitigera forceps, ventral view of hypopharynx {Hphy), suspensorial 
plates (HS), their apodemes (HA) and vmiting ligament (/). 

D, Heterojapyx gaUardi, ventral view of right maxilla, hypopharynx (Hphy), 
and hypopharyngeal apodemes (HA) upon which arise muscles of the maxilla 
(admx), the labium (Ibmcl), and the mandibles (not shown). 

E, Ncsoniachilis maoriciis, posterior view of unconnected anterior and pos- 
terior arms of tentorium (HA, PT), part of the head wall with clypeus (CIp) 
and labrum (Lin), base of maxilla (Mx), and mandible (Md). 

F, Ephemerid nymph, ventral view of tentorium and part of left side of head, 
showing anterior tentorial arms (AT) arising from ventral margin of gena 
(Ge). 



ligament. In the pterygote insects the hypopharyngeal muscles, the 
ventral dilators of the pharynx, and most of the fibers of the ventral 
adductors of the mouth part appendages arise on the endoskeletal 
structure of the head known as the tentoriion. Evidentlv, then, the 



50 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8 1 

tentorium must have some relationship with the hypopharyngeal 
apophyses of the Apterygota and the Chilopoda, and with the sternal 
apodemes of the gnathal segments in the Crustacea. The nature of 
this relationship will be shown following the anatomical description of 
the tentorium. 

THE TENTORIUM 

The tentorium of orthopteroid insects is a horizontal, X-shaped 
brace between the lower edges of the cranial walls (fig. 39 B, Tut). 
It consists of a central body with a pair of divergent anterior arms 
(AT) and a pair of divergent posterior arms (PT) . The arms are 
hollow invaginations of the head wall. The roots of the anterior arms 
appear as external pits, in most insects lying just before the anterior 
articulations of the mandibles (fig. 18 A, B, at) in the epistomal suture, 
when the latter is present ; the roots of the posterior arms form de- 
pressions in the lower ends of the postoccipital suture (B, C, /^O- 
Usually there is a pair of internal processes, or dorsal arms of the 
tentorium (fig. 39 A, C, DT), arising centrally at the junction of the 
anterior arms with the body, and extending dorsally and anteriorly 
to the facial wall of the head near the bases of the antennae. Some- 
times these arms are fused with the cuticula of the cranial wall, but 
generally they are attached only to the hypodermis, and often their 
outer ends are weak and tendinous. Riley (1904) says that the dorsal 
arms of the tentorium of Blatta arise in the embryo as processes from 
the inner ends of the anterior arms. The tentorium undergoes many 
modifications of form in different insects, according as certain parts 
become more highly developed and others reduced, but its typical 
structure is seldom obscured. 

In its typical form, the tentorium is a simple " tent," as its name 
implies, composed of the central plate, or body, suspended by the four 
stays, or arms, from the four ventral angles of the head. Yet, mor- 
phologists have always been suspicious of accepting the tentorial 
structure at its apparent face value. Some writers would homologize 
the arms with the apophyses of the thoracic pleura, others with the 
apophyses of the thoracic sterna. Either disposition suggests, then, 
that there should be a pair of such processes for each of the head 
segments. Wheeler (1889) thought that he found in the embryo of 
Lcptinotarsa (Doryphora) five pairs of tentorial invaginations, repre- 
senting each head segment but the last. Other investigators have not 
verified this, and most students of the development of the insect head 
report the presence of only the two pairs of invaginations that form 
the anterior and the posterior arms of the definitive structure. 



NO. 3 INSECT HEAD SNOIX^RASS 5E 

Besides bracing the walls of the cranium, the tentorium gives attach- 
ment to muscles of the hypopharynx, of the mandibles (in some in- 
sects), of the maxillae, of the labium, of the pharynx, and, when 
dorsal arms are present, to muscles of the antennae. Such a com- 
prehensive relation to the musculature of the head appendages, there- 
fore, furnishes ample ground for the suspicion that the tentorium 
includes in its composition more than is evident in its adult structure. 
Janet (1899), after making a careful analysis of the muscles arising 
upon the tentorium in the head of an ant, concluded that the tentorium 
must be composed at least of three pairs of processes corresponding 
with the antennal, the maxillary, and the labial segments. The antennal 
processes, according to Janet's homolog}^ are the anterior arms, the 
labial processes are the posterior arms ; the maxillary processes are 
assumed to have lost their connection with the head wall, after their 
inner ends had united with those of the other processes in the formation 
of the central tentorial body. Janet's scheme, however, is not complete 
without the assumption of mandibular elements in the tentorium, for, 
in some of the lower insects, certain muscles of the mandibles are 
attached upon the tentorium. Since these muscles were not then 
known, Janet suggested that the homotypes of the mandibular ten- 
torial processes are represented on the mandibular segment by the 
points where the corpora allata have their origin in the hypodermis. 
All the tentorial processes, both real and hypothetical, Janet regarded 
as homologous with the f ureal invaginations of the thoracic sterna, 
because the tentorium of the adult insect supports the adductor 
muscles of the head appendages. This is sound reasoning, and the 
conclusion probably comes as close to the truth in the matter as the 
truth may be approached by induction from the facts presented by 
the higher insects ; but a study of the Apterygota, the Myriapoda, and 
the Crustacea throws an entirely new light on the origin and evolution 
of the tentorium, and dispels the obscurity which has led to so many 
theories concerning the nature of this head structure. 

The morphology of the tentorium, briefly summarized from facts 
later to be described, is as follows : The anterior arms and the part of 
the body of the tentorium on which the ventral adductor muscles of the 
mandibles, the maxillae, and the labium have their origin are identical 
with the hypopharyngeal apophyses of the Myriapoda and Apterygota, 
and have their prototypes in the ventral apodemes of the gnathal seg- 
ments in Crustacea. From their positions just laterad of the hypo- 
pharynx, the bases of the apophyses have moved outward in the ventral 
wall of the head before the leases of the mandibles to the lateral ventral 
edges of the cranium, where thev come to lie in the subgenal sutures. 



52 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

Then, proceeding forward, they have migrated to the fronto-clypeal 
suture on the facial aspect of the head. The primitive condition is 
found in Chilopoda, Diplopoda, and Apterygota; intermediate con- 
ditions occur in the Ephemerida and Odonata ; the final condition is 
characteristic of all Pterygota, except the Ephemerida and Odonata. 
The posterior tentorial arms are invaginations in the lower ends of 
the postoccipital suture of the cranium, which is probably the inter- 
segmental groove between the first and second maxillary segments. 
These arms are absent in the Myriapoda and most Apterygota ; they 
are present in Machilis and in some Crustacea, where their inner ends 
are united to form a transverse bar through the back of the head ; 
they are present in all Pterygota, where the anterior arms are united 
with them to form the typical four-branched tentorium. The dorsal 
tentorial arms are processes of the anterior arms and may secondarily 
become attached to the dorsal or facial wall of the cranium. 

The muscles of the tentorium, with the exception of the antennal 
muscles usually arising on the dorsal arms in pterygote insects, are 
all muscles that primitively have their origin on the sterna of the 
gnathal segments. They include two sets of median longitudinal 
ventral muscles, one set going anteriorly to the hypopharynx, and 
the other posteriorly to the sternum or sternal processes of the pro- 
thorax ; they include also the transverse ventral adductors of the 
mandibles, the first maxillae, and the second maxillae, and the ventral 
dilators of the phaiynx. In the Chilopoda and Apterygota, all these 
muscles arise from the hypopharyngeal apodemes, except some of the 
mandibular muscles which may become detached from the apophyses, 
or retain a direct connection with the base of the hypopharynx. The 
hypopharyngeal apodemes are, therefore, paired apophyses of the 
region of the gnathal sterna. There is no evidence that they are com- 
posite structures ; each appears to be a single process invaginated 
from a chitinous remnant of the mandibular sternum (the suspensorial 
plate of the hypopharynx), but since it bears the sternal muscles of 
the three gnathal appendages, either the bases of these muscles have 
migrated forward, or each apophysis is a process of the three united 
sterna. When the two apophyses move to the positions on the front 
wall of the head characteristic of the orthopteroid branch of the 
Pterygota, they retain the muscle attachments, and when they unite 
with the posterior arms to form the typical tentorium, the head pre- 
sents the aspect of having none of the ordinary sternal muscles of the 
appendages attached on its sternal region, except for the small mandib- 
ular adductors present in some of the lower Pterygota that have 
retained their origin directly on the base of the hypopharynx. 



NO. 3 INSECT HEAD SNODGRASS 53 

The antennal muscles that take their origin on the dorsal arms of 
the tentorium in most adult pterygote insects have evidently migrated 
secondaril}^ to this position after the attachment of these arms to the 
dorsal wall of the cranium. In the crustaceans, myriapods, and many 
insect larvae, the antennal muscles have the primitive attachment on 
the walls of the head capsule (figs. 23 B, 50 B, C, E, F, 5). 

Evidence fully supporting the above statements is easily adduced 
from a comparative study of the head structure and the gnathal mus- 
culature in the Myriapoda, Apterygota, Ephemerida, Odonata, and 
orthopteroid Pterygota. Many of the facts have been described by 
other writers, but their significance appears to have been unrecognized. 

In the Chilopoda, the hypopharyngeal apodemes are large chitinous 
processes (fig. 21 A, B, HA) that arise from the inner ends of the 
suspensorial plates of the hypopharynx (HS) close to the base of 
the hypopharynx (Hphy). Each projects posteriorly at the side of 
the pharynx, and the two are bridged below the pharynx by a sheet 
of ligamentous tissue (A, C, ;'). Upon the arms, or on processes of 
the arms, and on the uniting ligament arise the ventral adductor 
muscles of the mandibles (B,KL), and of the first and second 
maxillae. The relations here are the same as in the thorax of an insect 
where the ventral leg muscles arise from a pair of sternal apophyses. 
In the Diplopoda, a highly specialized condition has arisen through 
the separation of the inner ends of the muscles from the apodemes 
and their union across the median line by a tough transverse ligament 
(fig. 26 A, A-). The large mandibular adductors (KL, KL) here 
pull against each other from the two ends of the ligament. The liga- 
mentous bridge suggests, in a way, the body of a tentorium, but as 
will be seen it has no relation to the insect tentorium. A similar con- 
dition of the mandibular adductors exists in many of the Crustacea 
(fig. 2y A, B, KL), and in some of the fibers of these muscles in the 
apterygote insects (C, D, KLk), as will be descril)e(l later in con- 
nection with the mandibles (page 62). 

In the Apterygota, the hypopharyngeal apodemes are well developed 
and extend far back in the head. Those of Japyx (fig. 21 D, HA) are 
slender rods running parallel beneath the sides of the pharynx and 
then diverging outward and posteriorly to the head wall behind the 
cardines of the maxillae (Cd), but their ends appear to be free and 
not attached to the cuticula of the cranium. Upon these arms arise 
the hypopharyngeal retractor muscles, a set of mandibular adductors 
(fig. 2'/ C, KLt), the adductors of the maxillary stipes and cardo 
(fig. 21 D, admx), and muscles of the labium (Ibmcl). The hypo- 
pharyngeal skeleton of Japyx was described first by Meinert (1867), 



54 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8 1 

and later by von Stumnier-Traunfels (1891). The latter writer called 
it the " Stiitzegerust,'' or supporting framework of the hypopharynx ; 
he figured it in Tetrodoiitopliura gigas and in Campodca staphylinus, 
and he says it has essentially the same structure in Japyx, Campodea, 
and Collembola. Folsom (1899) described the hypopharyngeal skele- 
ton of the collembolan, Orchcsella cincta, as consisting of a thin 
median plate with paired anterior, dorsal, and posterior arms. The 
anterior arms, he says, are united with the lateral lobes of the hypo- 
pharynx, the others are attached to the cranial walls by fibrous strands. 
This structure of the collembolan head, upon which arise muscles 
of the pharynx, the mandibles, and the maxillae, Folsom points out 
is the true tentorium, homologous with that of the Orthoptera and 
other mandibulate insects. The failure to recognize this fact, he 
says, " has led students to assign an altogether undue importance to 
the * Stutzapparat ' of the ligula (hypopharynx), which has errone- 
ously been regarded as a sort of substitute for a tentorium." " Partly 
as a result of this error," he adds, " systematists have acquired an 
exaggerated opinion of the dififerences which separate Collembola 
and Thysanura from insects of other orders." 

The tentorium of the Protura has been described by Berlese (1910) 
and by Prell (1913). The anterior arms of the structure are united 
in a median bar, but each arm itself is forked anteriorly, and the 
two forks are said by Prell to make connections with the base of the 
hypopharynx and with the fronto-clypeal ridge of the head. Both 
Berlese and Prell call this endoskeletal structure of the proturan head 
the " tentorium," but Prell observes that it has a close resemblance 
to the " Zungenapparat " of the Collembola and suggests a homology 
with this structure. It is now to be seen that the two structures are, 
indeed, identical, and that the hypopharyngeal apophyses of the 
Apterygota are the primary elements of the pterygote tentorium. 

In Machilis (figs. 21 E, 27 D), the hypopharyngeal apodemes 
(HA) arise from suspensorial plates (fig. 21 E, HS) connected later- 
ally with the cranial walls as in the chilopods, but their points of origin 
from these plates are at the basal angles of the clypeus (Clp). There 
is in Machilis also a well-developed posterior tentorial bar (PT) ex- 
tending transversely through the back of the head from pits (pt) 
in the lower ends of the postoccipital suture. The maxillary cardines 
(Cd) are attached to the margin of the cranium just anterior to these 
posterior tentorial depressions. The inner ends of the hypopharyn- 
geal apodemes (HA), or anterior tentorial arms, of Machilis become 
weak and fibrous, and in specimens cleaned in caustic they do not 
connect with the posterior tentorial bar. The tentorium of Machilis. 



NO. 3 INSECT HEAD SNOUGRASS 55 

therefore, appears to be in an intermediate stage of development in 
which the anterior and posterior elements are still independent of 
each other. A two-branded fiber (q) extends downward in the head 
from the middle of the posterior bar. A similar tentorial bar is 
strongly developed in the crustacean, Gaimnarus (fig. 28B, PT). 

In all the pterygote insects the anterior and the posterior arms of 
the tentorium are united with each other, and typically the lateral 
elements are fused across the median line to form the central plate- 
like body of the tentorium (figs. 21 F, 39 B, Tut). The median plate, 
however, is not developed in all cases ; in the caterpillars the posterior 
arms form only a slender bar through the back of the head, to which 
the anterior arms are attached on each side (fig. 53 D, Tnt), and a 
similar condition exists in adults of the higher Hymenoptera, where 
the posterior bar appears as a slender yoke between the posterior ends 
of the large anterior arms. In all insects of the orthopteroid branch 
of the Pterygota, the roots of the anterior tentorial arms lie in the 
fronto-clypeal suture (figs. 18 A, B, 36 A, B, 46 A, B, D, F, at, at). 
So constantly do they have this position that they become diagnostic 
marks of the suture, or of the fronto-clypeal line when a suture is 
absent. In the Ephemerida (nymphs), however, the roots of the 
broad anterior arms (fig. 21 F, at) lie at the edges of the inflected 
ventral areas of the genae (Ge), before the bases of the mandibles. 
Here, clearly, is a more primitive condition, dififering from that of 
the Myriapoda and Apterygota only in that the bases of the hypo- 
pharyngeal apodemes have moved outward from the hypopharynx 
to the lateral walls of the cranium. In the Odonata the roots of the 
anterior tentorial arms lie on the sides of the head, above the bases of 
the mandibles, in the subgenal sutures. This is a second step toward 
the orthopteroid condition, in which finally the tentorial roots have 
migrated anteriorly into the fronto-clypeal suture on the facial aspect 
of the head. 

The writer believes that the facts presented in the foregoing de- 
scriptions solve the riddle of the insect tentorium, and explain the 
seeming anomalies of the gnathal musculature, though he has not 
shown the mode of union between the anterior and the posterior arms 
in forming the characteristic tentorium of pterygote insects, and 
though the method of the change in the connections of the anterior 
arms from the base of the hypopharynx to the facial aspect of the 
head may still be held as not exactly determined. The origin of the 
anterior tentorial arms as apophyses of the sternal region of the 
gnathal segments, however, shows that the adductor muscles of the 
gnathal appendages, which arise on the tentorium in pterygote insects. 



56 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOL. 



are the true sternal muscles of the head appendages, and this relation 
brings the musculature of these appendages directly in line with that 
of the thoracic legs, which are moved by sets of muscles arising on 
the tergum and the sternum in each segment. In the Pterygota, it 
will further be shown, the mandibles lose their primitive sternal ad- 
ductors, and, by a change in the nature of the mandibular articulation 
with the head, the primitive tergal promotor and remoter muscles of 
the jaw become the functional abductors and adductors. 



III. THE HEz\D APPENDAGES 

The segmental appendages of the head in an adult insect are the 
antennae, the mandibles, the maxillae, and the labium. The antennae 



Pi 

-" Lm 
-- ,^ ' ^ , lAnt 

i^-^ vi^ -2Ant 



Mth 
An 



A 



Lm Ant 



.Ch 





Fig. 22. — Arthropod embryos showing relative development of the trito- 
cerebral appendages. 

A, embryo of a crayfish, Aslacus (Potatiwhius) asiactts (from Reichen- 
bach, 1877). B, embryo of a spider, Trochosa singoricnsis (from Jaworowski, 
1891). C, embryo of a spider, Angeleua labyrinthca (from Balfour, 1880). 
D, embryo of an apterygote insect, Auurida maritiina (from Wheeler, 1893). 

An, anus; Ant, antenna; lAiit, first antenna; 2Ant, second antenna; Ch, 
chelicera ; ///, tritocerebral segment ; /L, first leg ; Li, prothoracic leg ; Lm. 
labrum ; Md, mandible ; Mth, mouth ; Pdp, pedipalp ; Pi. pit on head region ; 
Pnt, postantennal appendage ; Pre. protocephalon. 

belong to the second, or deutocerebral, segment of the protocephalon. 
the other appendages to the gnathal segments. In many insect em- 
bryos there is present a pair of small lol^es on the third protocephalic 
segment, which lobes are unquestionably rudiments of the tritocere- 
bral appendages. Preantennal a)3pendages have been reported in Scolo- 
pendra and in the phasmid insect, Caransius (fig. 14 A, B Prnt) . As 
already pointed out, there is some reason for regarding the crustacean 
eye stalks as being the appendages of the preantennal segment, though 
the true status of these organs has not yet been demonstrated. 



NO. 3 



INSECT HEAD SNODGKASS 



57 



The eye stalks of the decapod crustaceans arise from the ends of a 
transverse ridge on the top of the protocephalon, and project later- 
ally from mider the base of the rostrum, the latter being a process of 
the anterior edge of the carapace, and, therefore, from the tergum 
of the mandibular segment. Each eye stalk (fig. 17 B) consists of two 
movable segments, a narrow basal one forming a short peduncle, and 
a large terminal one capped by the hemispherical compound eye. 
Schmidt (1915) enumerates ten individual muscles for each eye stalk 
in the crayfish, the basal segment being provided with muscles arising 
on the head walls that move the appendage as a whole, while muscles 
from the basal segment move the terminal eye-bearing segment. The 
eye muscles are innervated by an oculo-motor nerve arising from the 
brain near the base of the sensory optic nerve. 



THE ANTENNAE 



The insect antenna is typically a many-jointed filament. Usually 
the first two basal segments are dififerentiated from the rest of the 





B 

Fig. 23. — The antenna. 

A, diagram of typical segmentation and articulation of an insect antenna. 
B, head of a chilopod, Scutigcra forceps, dorsal, showing dorsal articulation of 
antennae, and origin of antennal muscles on walls of cranium. 

Ant, antenna; as, antennal suture; E, eye; 11. articular pivot of antenna; 
Pdc, pedicel ; Sep, scape ; FI, flagellum. 

shaft (fig. 23 A). The first segment serves to attach the antenna to 
the head, and, being often, thicker and longer than the others, forms a 
basal stalk, or scape (Sep), of the appendage. The second segment, 
or pedieel (Pde), is short, and in nearly all insects contains a special 
sensory apparatus known as the organ of Johnston. The part of the 
antenna beyond the pedicel is termed the flagelliiiii or clavola (Fl). 
The flagellum may be long and tapering and made up of many small 
segments, or it may be abbreviated, and reduced even to a single seg- 
ment. The scape is set upon a small membranous area of the head 
wall, sometimes depressed to form a cavity, or autcnual socket. 



58 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 81 

The head wall surrounding the antenna! base is strengthened by an 
niternal ridge, the line of which is marked externally by a suture 
(fig. 23, as), setting- off a circular, marginal rim known as the antennal 
sclerite. Usually a pivot-like process (;/) from the rim of the sclerite 
forms a special support and articular point for the base of the scape, 
and allows the antenna a free motion in all directions. In its single 
point of articulation with the head wall, the antenna resembles the 
maxilla, or the mandible of those apterygote insects in which the jaw 
does not have a double hinge with the cranium. In most pterygote 
insects the antennal pivot is ventral or postero-ventral in position, 
relative to the base of the antenna (fig. 23 A), while the single mandib- 
ular or maxillary articulations are dorsal. The ventral position of 
the antennal articulation might be supposed to have shifted during the 
forward and upward migration of the appendage from its primitive 
ventral and postoral situation ; but in Japyx the antennal pivot is 
dorsal, as it is also in the Chilopoda (fig. 23 B, n). 

Each antenna is moved by muscles inserted upon the base of the 
scape. The origin of the antennal muscles in adult pterygote insects 
is commonly on the dorsal, or dorsal and anterior arms of the ten- 
torium (fig. 38 D, DT, AT), but in the caterpillars (fig. 50 B, C, E, F) 
and in some coleopteran larvae, the antennal muscles arise upon 
the walls of the epicranium. The cranial origin of the muscles is prob- 
ably the primitive condition, for, as already shown, the tentorium 
belongs to the gnathal segments only. The attachment of the anten- 
nal muscles on the tentorium, therefore, appears to be a secondary 
condition that has resulted from the migration of the muscle bases to 
the dorsal tentorial arms when the latter make contact with the dorsal 
wall of the head. In Crustacea and Chilopoda the antennal muscles 
have their origin on the head wall. In Sciitigera (fig. 23 B) a dorsal 
set to each antenna arises on the dorsal wall of the cranium mesad 
and posterior to the antennal base, and a ventral set arises on the lat- 
eral walls below the antenna, and below the eyes. The insertion points 
of these muscles, distributed on three sides of the articular pivot {n), 
allow the muscles to act as levators, depressors, and rotators of the 
appendage. The part of the insect antenna distal to the scape is moved 
by muscles arising within the scape and inserted on the base of the 
pedicel (fig. 23 A). The segments of the flagellum in insects, however, 
so far as known to the writer, are never provided with muscles, and 
their lack of muscles suggests that the flagellum is a single segment 
secondarily subsegmented, corresponding with the flagellum of a 
crustacean antenna (fig. 24 B, Ft), which is a many-jointed dacty- 
lopodite. In the Myriapoda, however, all the antennal segments may 



j^O. 3 INSECT HEAD SNODGRASS 59 

be individually provided with muscles {Scolopendra, Spiroholus). 
The first antenna, or antennule, of the crayfish, according to Schmidt 
(1915), has paired antagonistic muscles for each of its first three 
proximal segments, and the third segment contains a single reductor 
inserted on the base of the dorsal branch of the flagelluni. but other- 
wise none of the flagellar segments is provided with muscles. 

The Arachnida and Xiphosura lack antennal appendages in the 
adult stage. Croneberg (1880) describes a pair of head lobes in the 
arachnid embryo, which he says fuse into a median rostrum in the 
mites and in the higher arachnids, and which he believes represent 
the antennal appendages. Jaworoski (1891) likewise describes in 
the embryo of a spider, Trochosa singoriensis, a pair of lobes situated 
before the chelicerae, which he claims are rudiments of the antennae 
(fig. 22 B, Ant), but he says the lobes disappear during later develop- 
ment. 

THE POSTANTENNAL APPENDAGES 

The pair of postantennal appendages on the tritocerebral segment 
of the head, known also as the antennae (Crustacea) , second antennae, 
premandibular appendages, and intercalary appendages, are at best 
rudimentary in all insects. According to Uzel (1897), two small 
lobes in the adult head of Campodea, lying between the labrum and 
the maxillae, in the space left free by the retracted mandibles, are 
the tritocerebral appendages ; the writer has found a pair of small 
papillae in Dissosteira between the bases of the mandibles and the 
angles of the mouth (fig. 42 B, Put) that might be vestiges of these 
organs Otherwise tritocerebral appendages are known m msects only 
as evanescent rudiments in the embryo (fig. 22 D, Put) . In the Myna- 
poda likewise, the postantennal appendages are lackmg, or possibly 
are present as temporary premandibular lobes on the head of the 
embryo ("rudiments of lower lip" in GcophUus, Zograf, 1883). In 
the Crustacea, on the other hand, the appendages of the tritocerebral 
segment, though sometimes reduced or lacking, are commonly highly 
developed, biramous organs, the second antennae, or " the antennae 
according to the terms of carcinology. In the decapods each appen- 
dage consists of a two-segmented base (fig. 24 B. Prtp), of a large, 
one-segmented exopodite (Exp), and of a long, slender endopodite 
(Endp) of which the terminal segment is the many-jointed flagellum 
\fI). The exopodite is independently movable by abductor and ad- 
ductor muscles arising in the second segment of the base 

In Xiphosura and Arachnida. the chelicerae (fig. 24 A) ^^'"^ f "" 
erally regarded as the appendages of the tritocerebral segment. Their 



60 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

rudiments in the embryo of a spider (fig. 22 C, Ch) bear a relation- 
ship to the head so similar to that of the tritocerebral rudiments in 
the insect embryo (D, Put), that the identity of the two sets of organs 
can scarcely be questioned. Holmgren (1916), furthermore, claims 
that the histology of the arachnid brain shows that the chelicerae are 
innervated from the tritocerebral region of the brain. If this homology 
is correct, there is no reason for calling the tritocerebral appendages 
" second antennae " except in the Crustacea. The arachnid chelicera 
is a uniramous organ, that of a scorpion (fig. 24 A) having three 
well-developed segments. 




Fig. 24. — Postantennal appendage of adult arthropods. 

A. chelicera of a scorpion, left, ventral view, showing uniramous structure 
and three segments. B, second antenna of a decapod crustacean (Spirontocaris 
(jrociilaiidiciis), left, ventral view, showing biramous structure, consisting of 
two-segmented base (Prtp) bearing an exopodite (Exp) and an endopodite 
(Endp). 

THE GNATHAL APPENDAGES 

There can be no doubt that the gnathal organs — the mandibles, the 
first maxillae, and the second maxillae — constitute a distinct group 
of appendages in the eugnathate arthropods. The mandibles are the 
most highly modified of the gnathal appendages, and, in most cases, 
their structure has lost all resemblance to that of the more generalized 
insect maxillae. A maxillary appendage, therefore, should be studied 
first as affording a better example of the basic structure of the gnathal 
organs, and, in insects, the first maxilla preserves most nearly the 
primitive structure, since the second maxillary appendages are united 
to form the labium. 

The first maxilla of an insect with typical biting mouth parts, of 
which the roach oft'ers a good example (fig. 25 A), consists of a basal 
stalk, two terminal lobes, and a palpus. The base is divided into a 
proximal cardo (Cd) , suspended from the head by a single point of 
articulation (c), and a distal stipes (St). The cardo and stipes are 
freely flexible on each other by a broad hinge line, and their planes 
may form an abrupt angle at the union, but neither has an inner wall, 



NO. 3 



INSECT HEAD SNODGRASS 



6i 



the two being merely strongly convex sclerites set upon the mem- 
branous lateral wall of the head, and their cavities are a part of the 
general head cavity. Only the terminal maxillary lobes and the palpus 
are free parts of the appendage. The lobes arise from the distal end 
of the stipes, one, the lacinia (Lc), being internal, the other, the galea 
(Ga) external. The galea is also anterior to the lacinia (or dorsal 
to it in insects with the head flattened and held horizontal). The 



KLcd 




Fig. 25. — Maxilla of Periplaneta. 



A, left maxilla, posterior (ventral) surface. B, internal surface of cardo. 
C, right maxilla, anterior (dorsal) view, showing muscles. 

Cd, cardo; e, articulation of cardo with cranium; fga, flexor of galea; 
Ucc, cranial flexor of lacinia ; Acs, stipital flexor of lacinia ; ft, f emoro-tibial 
joint of palpus; Ga, galea; /, promotor of cardo; KLcd, adductor of cardo 
(origin on tentorium) ; KLst. adductor of stipes (origin on tentorium) ; Lc, 
lacinia ; O, levator of palpus ; Plf, palpus ; ipip, first segment of palpus ; Q, 
depressor of palpus; q, submarginal suture (and internal ridge) near inner 
margin of stipes ; r, internal ridge of cardo ; St, stipes ; T, depressor of fourth 
segment (tibia) of palpus; V, depressor of fifth segment (tarsus) of palpus. 

galea is usually a soft lobe ; the lacinia is more strongly chitinized, 
and ends in a strong incisor point provided with one or more apical 
teeth curved inward. Both lobes are movable on the end of the stipes ; 
the galea can be deflexed, and the lacinia can be flexed inward. The 
palpus (Pip) arises from the lateral surface of the stipes, a short 
distance proximal to the base of the galea. The palpus of the roach is 
five-segmented. 

The musculature of the maxilla (tig. 25 C) comprises muscles that 
move the appendage as a whole, and muscles that move the terminal 



62 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8 1 

lobes and the palpus. The first group includes a tergal muscle (/) 
arising on the posterior dorsal wall of the head, and two sets of sternal 
muscles {KLcd, KLst) arising on the tentorium in most insects, or 
on the homologous hypopharyngeal apodemes in some apterygote 
insects (fig. 30 B, HA). The single tergal muscle (fig. 25 C, /) is 
inserted on the proximal end of the cardo just before the articulation 
of the latter with the head (c) ; it is probably a promotor, serving to 
swing the appendage forward. The sternal muscles (i. e., the tentorial 
or hypopharyngeal muscles) consist of two large flat bundles of 
libers, one group {KLcd) inserted on the inner face of the cardo, the 
other {KLst) on an internal ridge of the stipes near the mesal border 
of the posterior face of the latter (A, q). These muscles are the ad- 
ductors of the maxilla ; the fibers of the cardo muscle arise anterior 
(or dorsal) to those of the stipes muscle and cross them obliquely. 

The muscles of the movable parts of the maxilla include muscles 
of the galea, the lacinia, and the palpus. The galea has a single muscle 
(fig. 25 C, fga) arising on the posterior wall of the stipes and inserted 
on the posterior rim of the base of the galea ; it is a reductor in as 
much as it serves to flex the galea posteriorly ( or ventrally) . The 
lacinia has a large flexor {Hcs) arising in the base of the stipes, and a 
second muscle {flee) arising on the posterior dorsal wall of the 
cranium. In the roach these two muscles are inserted by a common 
broad tendinous base on the inner proximal angle of the lacinia ; in 
other insects they usually have separate insertions (fig. 30 B, Hes and 
flee, fig. 40 B, 14, 75). The palpus is provided with two muscles 
(fig. 25 C,0,Q), both of which arise within the stipes and are in- 
serted on the base of the first segment of the palpus (A, iplp). The 
two palpus muscles are more distinct in most other insects than in the 
roach (fig. 31 A, B, C, E), and since one is dorsal and the other ven- 
tral, relative to the morphologically vertical axis of the maxilla, they 
are clearly a levator and a depressor, or abductor (O) and adductor 
(()), of the palpus. The muscles within tbe ]ial])us vary somewhat \v. 
dififerent insects. In the palpus of the roach, a levator of the second 
segment arises in the first, where also a long depressor of the fourth 
seginent (T) has its origin. A depressor of the terminal segment {V) 
arises ventrally in the penultimate segment. 

THE MANDIBLES 

The most generalized manciil)u!ar api»eu(lage in the arthropods. 
i. e., one corresponding most closely in structure and musculature with 
a typical maxilla, is to be found, not in the insects or crustaceans, but 
in the myriapods, and best developed in the Diplopoda. 



NO. 3 



INSECT HEAD SNODGRASS 



63 



The diplopod mandible consists of a large basal plate, which appears 
to form an extensive part of the lateral head wall (fig. 17 K, Add), 
and of a movable terminal lobe mostly concealed in the normal con- 
dition by the gnathochilarium (Gch). The basal plate is subdivided 
into several regions, but particularly there is a proximal piece (fig. 
26 A, Cd) and a distal piece (St), separated by a line of flexibility. 
The proximal piece is loosely articulated to the head wall by a single 
point on its dorsal posterior angle (a). The entire mandibular base 
is slightly movable by its membranous union with the head, but it is 
not of the nature of a free appendicular structure, since it has no inner 
wall — it is merely a convex plate in the lateral wall of the head, but 

KL I flee flee a 

.^^:^m^^ /KL 

ij' . " y^ KL ••=*•^- 




fTxair-ii/n-^i-f.. 



flcs 




A B Le- 

Fig. 26. — Mandibles of Myriapoda. 



A, right mandible of a diplopod, Thyropygus (Spirostreptus), dorsal, showing 
large dumb-bell adductors (KL, KL) from opposite mandibles, united by median 
tendon (k). B, left mandible of a chilopod, Scutlgera forceps, lateral view. 
C, right mandible of Sciitigera, dorsal, somewhat diagrammatic. 

a, articulation of mandible with cranium; BP, basal plate of inaudible; Cd, 
" cardo " of mandible ; flee, cranial flexor of lacinia ; flcs, stipital flexor of 
lacinia ; /, promoter of mandible ; /, remotor of mandible ; k, median tendon of 
mandibular adductors ; KL, mandibular adductors, united by median tendon in 
diplopod (A, k) to form dumb-bell muscle; Lc, lacinia; St, " stipes" of mandible. 

separated from the cranium by a membranous suture. The free ter- 
minal lobe of the mandible is a strongly chitinized, jaw-like structure 
with a proximal molar area and terminal incisor point (fig. 26 A, Lc ) . 
It is hinged by a dorsal articulation at its base with the end of the basal 
plate. 

So closely do the parts of the diplopod mandible (fig. 26 A) re- 
semble the cardo, the stipes, and the lacinia of an insect maxilla 
(fig. 25 A), that the imagination at once sees in the diplopod ja\v 
an appendage similar to the maxilla, lacking only a galea and a palpus. 
That the fancied resemblance is real is easily demonstrated by a study 
of the musculature. 

The musculature of the diplopod mandible consists of muscles that 
move the appendage as a whole, and of muscles that move the lacinial 

5 



64 SMITHSUMAN MISCELLANEOUS COLLECTIONS VOL. 8l 

lobe. As in the insect maxilla, the muscles that move the entire organ 
include a tergal promoter and a group of ventral adductors. The 
promoter (fig. 26 A. /) arises on the wall of the cranium dorsal and 
posterior to the articulation of the basal plate with the head. It is 
inserted on the dorsal (anterior) margin of the distal division {St) 
of the basal plate, and in its point of insertion alone does this muscle 
differ from the promoter of the insect maxilla, which is inserted en 
the edge of the carde (fig. 25 C, /). Functionally, however, the two 
muscles are the same, and a shift in the point of attachment is not a 
morphological difference. 

The adductor muscles of the diplopod mandible consist principally 
of a great mass of fibers (fig. 26 A, KL) filling the cavity of both divi- 
sions of the basal plate (Cd and St). These muscles are clearly the 
homelogues of the adductors of the cardo and the stipes in the insect 
maxilla (fig. 25. KLcd, KLst), which have their origins on the ten- 
torium, or on the hypepharyngeal apodemes. In the diplopod mandi- 
bles, however, the fibers of the adductor muscles converge medially 
from each jaw upon a large, tough, transverse ligament (fig. 26 A, k), 
and the two conical fiber masses, together with the connecting liga- 
ment, form a great dumb-liell-shaped muscle uniting the two man- 
dibles. The two sets of fibers pull against each other to close the jaws. 
Clearly, the inner ends of these muscles have become detached from 
the hypepharyngeal apodemes. and the fibers from opposite sides have 
been united across the middle of the head by means of a transverse 
ligament. There is also, however, a small group of adductor fibers to 
each mandible (not seen in the figure) that still retains a connection 
with the corresponding apodeme of the hypepharynx. Besides the 
mandibular muscles, other muscles have their origin on the transverse 
ligament, including muscles to the gnathochilarium, which is either the 
united second maxillae, or the combined first and second maxillary 
appendages. In the Diplopoda, therefore, the ventral adductors of all 
the gnathal ap]')endages have lost their sternal connections by their de- 
tachment from the hypepharyngeal apodemes. This is a specialized 
condition, and the ligamentous bridge en which the muscles arise has 
no relation to the insect tentorium. 

The muscles of the free terminal lobe of the diplopod mandible 
(fig. 26 A./,r) include a muscle inserted directl}- on the base of the 
lobe (fics) arising within the stipes (St), and a large cranial muscle 
(Hcc) arising on the dorsal wall of the head and inserted by a strong, 
chitineus apodeme on the inner basal angle of the lobe. These muscles 
corresijond exactly with the lacinial flexors of the insect maxilla, one 
of which (fig. 25 C. tJcs) arises wnthin the stipes, the ether (tlcc) en the 



NO. 3 INSECT HEAL) SNODGKASS 65 

dorsal wall of the cranium. In most insects the second muscle is in- 
serted, as in the diplopod, on a chitinous apodeme from the inner angle 
of the lacinia (fig. 30 B, flee) . There can be little question, therefore, 
that the single lobe (Le) of the diplopod mandible is the lacinia, and 
that the jaw of the Diplopoda has a structure identical with that of 
the insect maxilla, except for the lack of a galea and a palpus. 

The mandible of the Chilopoda is more specialized in structure than 
is that of the diplopods, but in its musculature it is in some respects 
more generalized. In Scolopendra, Lithohius, Scutigera, the jaw is 
slender and greatly elongate. In Scutigera (fig. 17 G, Md) its taper- 
ing base is exposed on the side of the head where it is articulated to 
the cranial margin (a), but in Seolopcndra (fig. 21 B) the end of the 
mandible is buried in a pocket of the head wall lying mesad of the 
base of the maxilla {MxC). The long basal plate of the chilopod jaw 
is undivided (fig. 26 B, BP), and is articulated to the head wall by its 
apical point (a). In some chilopods there is an anterior articulation 
between the mandible and the suspensorial plate of the hypopharynx, 
but this articulation is a mere contact between external surfaces. 
As in the diplopods, the basal plate has no inner wall. The distal 
part of the mandible is a free lobe {Lc) movable on the base, but not 
so definitely hinged to the latter as is that of the diplopod mandible. 

The musculature of the chilopod mandible is practically alike in 
both the Pleurostigma and the Notostigma, and is essentially the same 
as in the diplopods. though the muscles differ in relative size. The 
basal plate is provided with both tergal and sternal muscles. Of the 
former, there are two sets of fibers, one inserted on the dorsal (an- 
terior) edge of the proximal part of the plate (fig. 26B,C, /), the 
other (/) on the ventral (posterior) edge; both have their origins 
on the dorsal wall of the cranium. These muscles apparently serve 
to rotate the mandible on its long axis, and they probably act as pro- 
tractors where the mandible is capable of a longitudinal movement ; 
but clearly the first would be a promotor, and the second a remotor 
in an appendage with primitive relations to the head. The sternal 
muscles of the mandible consist of a conical mass of adductor fibers 
(fig. 26B,C, A'L) spreading upon the inner wall of the basal plate 
from their median origin (fig. 21 ?>, KL), which is on the ligamentous 
l)ridge uniting the two apodemes of the hypopharynx (fig. 21 A, C, /). 
The adductors of the chilopod mandibles are unquestionably homo- 
logues of the dumb-bell muscle of the diplopods. The condition of 
the mandibular adductors, therefore, is more primitive in the Chilo- 
poda, for here the muscles retain their connections with the sternal, 
hypopharyngeal apodemes. 



66 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

The movable terminal lobe of the chilopod mandible (fig. 26 B, 
C, Lc) is provided with the same muscles as is the corresponding lobe 
of the diplopod mandible (A. Lc) and the lacinia of the insect maxilla 
(figs. 25 C, 30 15, Lc) . The muscle from the lobe to the basal plate in 
the chilopod jaw is very large (fig. 26 B, C, flcs), suggesting that of 
Japyx (fig. 30 B. -flcs), and is composed of two groups of fibers. The 
cranial muscle {ficc) arises by a broad base on the dorsal wall of the 
head, and is inserted on a slender apodeme from the inner angle of the 
lobe. In the chilopod mandible, therefore, there is a basal plate (fig. 
26 B, BP) corresponding with the cardo and stipes of the insect 
maxilla, but not divided as in the diplopods, and a free terminal lobe 
{Lc) which represents the lacinia. In retaining the connection of the 
adductor muscles with the hypopharyngeal apodemes, the chilopod 
mandible preserves the primitive condition shown by the maxilla of 
Japyx {fig. 2>o^). 

In the Crustacea and Hexapoda, the mandible, or the jaw part of 
the mandibular appendage, which may bear a palpus, consists of a 
single piece. Whatever may be the primitive elements that have 
entered into its composition, these elements are fused into a solid 
gnathal organ. There are, hence, never muscles entirely within ^the 
mandible, except those that pertain to the palpus, when a palpus is 
present. The mandibular musculature consists exclusively of the 
muscles that move the appendage as a whole, and these musdles cor- 
respond with the muscles of the basal plate of the myriapod mandible, 
or with those of the cardo and stipes of the insect maxilla. 

In the phyllopod crustacean Apits, the large mandibles (fig. 27 A, 
Md) hang vertically from the wall of the mandibular segment (IV). 
Each is a strongly convex, elongate oval structure, attached to the 
lateral membranous wall of the head by most of its inner margins, 
leaving only a ventral masticatory part projecting below as a free lobe. 
A single, dorsal point of suspension (a) allows the base of the man- 
dible to turn on its vertical axis, or to swing inward and outward as 
far as the membranous lateral head wall will permit. The musculature 
is correspondingly simple: two dorsal muscles from the tergum of 
the mandibular segment (IV) are inserted on the! base of the jaw, one 
(/) on the anterior margin, the other (/) on the posterior margin ; 
the hollow of the mandible is filled with a great mass of fibers (KL) 
which converge upon a median transverse ligament (k) that receives 
likewise the muscles from the opposite jaw. Here, then, is a ventral 
dumb-bell adductor, as in the diplopods, and two dorsal muscles, which 
may function either as productors and reductors, or as anterior and 
posterior rotators. It is not clear as to what constitutes the mechanism 



I 



NO. 3 



INSECT HEAD SXODGRASS 



67 



of abduction in appendages with this type of articulation and mus- 
culature. 

The Apus type of mandible is probably characteristic of most of 
the more generalized Crustacea; it is present also in some of the 

PcR 



Md 






Fig. 27. — Mandibles of Crustacea and Apterygota. 

A, mandibles of Apjis longicaudata (phyllopod), anterior. B, mandibles of 
Spirontocaris grocnlandicus (decapod), anterior. C, mandibles of Hetcrojapyx 
gallardi (apterygote insect), anterior (dorsal). D, mandibles of Xcsoiiiachilis 
maoricns (apterygote insect), posterior. 

a. articulation of mandible with cranium, or with wall of mandibular seg- 
ment (IV); HA, hypopharyngeal apophysis; /, promoter of mandible; /, 
remoter of mandible; k, median tendon of mandibular adductors of dumb-bell 
muscle {KL or KLk) ; KLk, fibers of mandibular adductors united by tendon 
{k) ; KLf, fibers of mandibular adductors retaining origin on hypopharyngeal 
apophyses (D, HA); m, suspensory tendons of mandibular adductors; Md, 
mandible ; PcR, posterior cranial ridge ; f, branch of labral muscle attached on 
mandible. 

decapods (Virbiiis, Spirontocaris). In Spirontocaris (fig. 27 B), the 
median ligament (k) of the dimib-bell adductors (KL) is connected 
with the hypodermis of the dorsal wall of the body by a branched arm 
(m) on each side. As before pointed out, however, the adductor liga- 



/ 



68 SMITHSONIAN MISCELLANEOUS COLLKCTIOXS VOL. 8l 

meat is in no sense to be homologized with the tentorium as developed 
in some of the higher Crustacea and in the pterygote insects. Each 
mandible of Spirontocaris is provided with two dorsal productor 
muscles (/), but a reductor was not observed. Spironiocavis preserves 
the primitive single dorsal point of articulation of the mandible (a) 
with the wall of its segment. In higher decapods, the am])hipods. and 
the isopods, where the mandible may have a double hinge with the 
wall of the head, the musculature of the organ is modified in a manner 
to be described later. 

The simple mechanism of the mandible of the higher pterygote in- 
sects is well understood ; the complicated musculature of the mandible 
in Apterygota has l)een given scant attention, and the derivation of 
the pterygote jaw mechanism from that of the Apterygota has been 
almost ignored. Borner ( 1909) has given the first comparative account 
of the mandibular musculature in the more generalized insects, and 
has pointed out certain points of similarity with the musculature of 
higher crustaceans. He did not, however, carry his comparisons to 
the myriapods, and thereby missed some fundamental relations. 

The mandibles of the Machilidae will serve best as an example of 
the more generalized apterygote jaw. The mandible of MacJiilis or 
of NcsoinachUis (fig. 27 D, Md) is surprisingly similar in form to 
that of the crustacean Apus {A), except that it has a long incisor 
point in addition to a broad molar lobe. In this latter character the 
machilid jaw resembles the mandibles of some of the decapod crus- 
taceans, such as Spi'irotocar'is and Virhhis, as has l)een pointed out by 
Crampton (1921b). The mandible of Machilis is suspended by a 
single dorsal point of articulation (a) against the lateral wall of the 
head. The cavity of the elongate base of each organ is filled by a mass 
of muscle fibers (KLk). and these fibers from the two mandibles con- 
verge upon the ends of a common transverse tendon (k) that passes 
through the base of the hypopharynx. Here, in an insect, therefore. 
we find the same type of dumb-bell adductor uniting the two mandibles 
as occurs in the Diplopoda and in lower Crustacea. In Madiilis. 
however, there is a second and larger set of adductor fil)ers (KlJ) 
which has its origin on the hypopharyngeal apodemes (HA). Machi- 
lis, therefore, in the possession of two dififerentiated sets of mandibular 
adductor fibers, combines the primitive condition of the chilopods 
with the specialized condition of the diplopods and lower crustaceans. 
The tergal musculature of the mandible in Machilis is simple, con- 
sisting of an anterior promotor (/) and a posterior remotor (/). The 
two muscles are disposed exactly as in Apus (A), and are in entire 



NO. 3 INSECT HEAD- — SNOlKiRASS 69 

conformity with the tergal musculature of the basal plate of the jaw 
of Scutigera (fig. 26 B, C, /, /) and other chilopods. 

The machilid type of mandibular musculature appears to be char- 
acteristic of most apterygote insects except the Lepismatidae. In 
Japyx and Campodea, the bases of the elongate mandibles and maxillae 
are deeply retracted into the head above the labium, and the edges 
of the labium are fused to the postgenal margins of the head, so that 
the distal tdgQ of the labium appears as the ventral lip of a pouch 
containing the other gnathal appendages and the hypopharynx. 

The mandibles of Hetero japyx (fig. 27 C, Md) are simple, slender 
organs, each consisting of a long, hollow basal piece, and of a more 
strongly chitinized free terminal lobe with a toothed incisor edge. 
The proximal tapering end of each jaw is set ofif from the rest by 
a thick internal ridge, superficially suggesting the division of the 
maxillary base into cardo and stipes ; but the " division " in the Japyx 
mandible gives rigidity instead of flexibility. The two mandibles of 
Heterojapyx are connected by a large dumb-bell adductor muscle 
(KLk), the spreading fibers of which fill the basal cavities of the 
organs. Besides this muscle there are also sets of ventral fibers (KLt) 
to the mandible that arises on the hypopharyngeal apophyses. The 
tergal muscles of the mandibles are large : they include for each jaw 
an anterior muscle (/) arising against a dorsal cranial ridge (PcR), 
and a wide fan of posterior fibers (/) arising along a median coronal 
ridge. Because of the retraction of the mouth appendages, the hypo- 
pharyngeal muscles of the mandibles (KLt) would appear to function 
as protractors, and the tergal muscles as retractors ; but the former are 
clearly the hypopharyngeal adductors of Machilis (D, KLt), and the 
latter the tergal promotors (7) and remotors (/). A peculiarity 
noted in Heterojapyx, if the writer observed correctly, is the attach- 
ment of a branch of the retractor of the labrum (t) on the base of 
the mandible. 

In the Collembola, which also have retracted mandibles and max- 
illae, the mandibular musculature would appear, from Folsom's 
( 1899) account of OrchcscUa c'mcta, to be of the same essential 
nature as that of Japyx. Folsom enumerates ten muscles for each 
mandii^le of OrchcscIIa. but they all fall into three groups according 
to their origins, namely, muscles arising on the walls of the head, 
muscles arising on the "tentorium" (hypopharyngeal apodemes), 
and fibers from one mandible to the other. The second and third 
groups constitute the adductors of the jaw ; their fibers are inserted. 
Folsom says, on the inside of the lateral wall of the mandible, and 
most of them have their origin on the " tentorium." but a few of the 



70 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 



fibers, he adds, '' pass under the tentorium and become continuous 
with similar fibers from the opposite mandible." Folsom, it will be 
noticed, says the adductor fibers connecting the mandibles pass be- 
neath the tentorial arms. In Japyx the tendon of the dumb-bell muscle 
distinctly lies dorsal to the hypopharyngeal apodemes. In Machilis 
the apodemes are so loosely connected with the base of the hypo- 
pharynx and so strongly united with the lateral inflections of the head 
wall, that in dissections their hypopharyngeal connections are easily 
lost, and the impression is given that the tendon of the dumb-bell 



lAnt 




J-~. 




iMxp 



A 

Fig. 28. — Head of Gammarus Jocusta (amphipod crustacean). 

A, lateral view of head, showing tergal abductors (/) and adductors 
(/) of left mandible, and base of ventral adductor (KL). B, postero-ventral 
view of back of head, showing origin of ventral adductors {KL) on posterior 
tentorial bar (PT). 

I Ant, first antenna ; 2Ant, second antenna ; /, abductor of mandible ; /, dorsal 
adductor of mandible ; KL, ventral adductor of mandible ; Lm, labrum ; Md, 
mandible; MdPIp, mandibular palpus; lALr, first maxilla; pMx, second maxilla; 
iMxp, first maxilliped ; pt, posterior tentorial pit ; PT, transverse posterior 
tentorial bar. 

adductor lies ventral to the apodemes. It does lie ventral to the sus- 
pensorial plates uniting the apodemes with the lateral walls of the 
head, but it passes anterior, i. e., dorsal, to the ends of the apodemes 
themselves. Folsom's statement, therefore, should be verified, for 
a discrepancy in the relations of the parts in question seems hardly 
permissible if we are dealing with homologous structures. 

The mandibles of the Protura, as described by Berlese (1909), are 
provided each with retractors and protractors that have their origins 
on the head wall, and with a protractor arising on the tentorial 
apodeme. Berlese, however, does not mention a muscle continuous 
between the two mandibles. The muscles present clearly represent 
the usual tergal muscles, and the hypopharyngeal adductor. 



NO. 3 INSECT HEAD SNODGKASS 7 1 

In all the apterygote forms thus far described, the mandible has 
a free attachment to the head, being implanted by most of its length 
in the ventro-lateral membranous part of the head wall, and articulated 
to the margin of the chitinous cranium by only a single dorsal point of 
contact. In the Lepismatidae, a new condition is established in the 
mandible through the elongation of its dorsal loase line forward and 
ventrally to the anterior end of the lower genal margin of the epicra- 
nium. The jaw thus becomes hinged to the head on a long basal axis 
extending from the primitive dorsal articulation, which is now pos- 
terior, to the angle between the genal margin of the head and the 
clypeus. At the latter point a secondary, anterior articulation is 
established between the mandible and the cranium. Bonier (1909) 
describes the articulation of the mandible of Lepisma, but he does 
not observe that its type of structure is characteristic of the Lepis- 
matidae only, not of the Apterygota in general. The alteration in the 
mandibular articulation involves a change in the entire mechanism 
of the jaw, and initiates the series of modifications that have led 
to the evolution of the pterygote type of mandibular musculature from 
that of Machilis, J a pyx, and the Collembola. 

The musculature of the mandible of Lepisma, as described by 
Borner (1909), is apparently almost the same as that of Machilis. 
The adductor muscles inserted within the body of the mandible consist 
of a large dorsal set of fibers (fig. 29 B, KLt) from the tentorium 
representing the fibers that arise on the hypopharyngeal apodeme of 
Machilis (figs. 27 D, 29 A, KLt), and of a small ventral set (KLh) 
arising directly from the hypopharynx. The tergal muscles comprise 
a pair of abductors (/) inserted on the outer margin of the mandibular 
base between the two articular points (a, c), and a large dorsal ad- 
ductor (/) inserted on the inner margin mesad of the posterior artic- 
ulation. The tergal abductors and adductor, however, are clearly 
the promotor and the remotor of the mandible of Machilis (fig. 29 A, 
/, /) and of all other generalized forms, which have assumed a new 
function by reason of the change in the nature of the mandibular 
articulation. 

The structure and musculature of the mandible in nymphs of Ephe- 
merida is essentially the same as in Lepisma. Borner describes and 
figures the nymph of Cloeon dipteruni, showing the presence of a 
large tentorial adductor and a very small hypopharyngeal adductor, 
in addition to the dorsal abductors and adductors ; the writer has 
verified the existence of all these muscles in another ephemerid 
species. In a dragonfly nymph, Aeschna, a small hypopharyngeal 
adductor was found, but no tentorial fibers were observed. In the 



72 



SMITIISOXIAX ^[ISCKLLANEOLS COLI-ECTJOXS 



VOL. 



8l 



orthopteron, Locusta, Bonier shows two small tentorial adductors of 
the mandible (fig. 29 C, KLt) , and a small hypopharyngeal adductor 
(KLIi). The same muscles the writer has found in Microccntrum, 
the hypopharyngeal fibers being attached medially on the tips of the 
rudimentary suspensorial arms of the hypopharynx (fig. 20 D, KLJi) ; 
but no trace of either set could be discovered in the acridid, Dissos- 
teira. Mangan ( 1908) described in the roach, Pcriplancta auslrakisiae, 
both a tentorial adductor and a hypopharyngeal adductor. The first 



'--KLt 



KLk' 





A 



Fig. 29. — Three sta.sfes in the evolution of the mandibular mechanism in 
biting insects. 

A, mandible of Machilis. outer surface, with single dorsal point of articulation 
(a) with cranium; the jaw moved by tergal promoter (/) and remotor (/), 
and by ventral adductors (KLk, KLt, see fig. 27 D). 

J>, mandible of Lcpisma (from Borner, 1909), articulated with cranium on 
long basal hinge inclined downward anteriorly from dori;al articulation (a) to 
anterior articulation (r) ; the promoters (/) here become abductors, and the 
remotor (/) becomes a tergal adductor; ventral adductor (KLh, KLt) retained. 

C, head of Locusta (from Borner, 1909), showing common type of mandibular 
articulation in pterygote insects, w-ith hinge line inclined downward posteriorly 
from anterior articulation (c) to posterior articulation (a) ; tergal abductors 
and adductors (/, /) highly developed, ventral adductors {KLh, KLt) rudi- 
mentary. In In'gher Pterygota the ventral adductors disappear. 

mention of either of these muscles is liy Basch (1865), who found 
the tentorial adductor in the mandible of Tcrines Havipes. 

The adductor fibers arising directly from the base of the hypo- 
pharynx are evidently remnants of the primitive sternal adductors that 
have retained their original connections. /;/ the insects, tlicreforc, 
the primary, sternal adductor muscles {KL) of the mandibles have 
become differentiated into three groups of fibers, the fibers of one 
group {KLh) retaining the primitive sternal connection, those of the 
second {KLt) being carried inzvard upon the sternal (hypopharyngeal) 
apophyses, those of the third (KLk), after having united medially 






I 



NO. 3 INSECT HRAl) SNODGKASS 73 

z^'ith the corresponding set from the opposite mandible, having been 
detached from all connections except their points of insertion on the 
mandibles. With the change in the mandibular articulation from a 
single dorsal suspensory point to a long basal hinge, the primary ad- 
ductors have lost their importance, and the function of adduction 
has been secondarily taken over by the primary tergal remotor, while 
the original tergal jjroniutor becomes the alxluctor. Remnants of the 
primary adductors in insects having a hinged mandi])le ])ersist in 
the Lepismatidae, Ephemerida, r)rth()ptera, and Isoptera, but in the 
higher orders they have disappeared. 

A still further evolution in the mandibular base has reversed the 
tilt of the hinge line. Instead of sloping from the posterior articulation 
downward and forward, as it does in Lepisma and in some ephemerid 
nymphs, the base of the jaw in all higher insects is inclined from the 
anterior articulation downward and posteriorly (fig. 29 C). This 
change in the slope of the axis of the hinge causes the apex of the 
jaw to swing inward and posteriorly during adduction, instead of in- 
ward and anteriorly as in the first condition. 

In the higher decapod crustaceans, and in the amphipods and iso- 
pods, the mandible has undergone an evolution parallel to that which 
has taken place in insects. Bonier (1909) has descril)ed the mandible 
and mandibular musculature of Gammarus, an amphipod, and has 
shown the structural similarity with the mandible of Lepisma. In 
Gammarus locusta (fig. 28 A) the mandible is hinged to the cranium 
l)y its long base, which slopes downward and forward from the pos- 
terior point of articulation. The primitive tergal ])roniotor muscle 
(7) has then become an al)ductor, and the remotor (/) has become 
a dorsal adductor. The primitive ventral adductor (KL) has its 
origin on a well-developed transverse tentorial bar (B, PT) passing 
through the back of the head ; a hypopharyngeal branch of the 
adductor is lacking. In the crayfish (Astacus), Schmidt (1915) 
describes an anterior ventral adductor of the mandible arising on the 
anterior end of the ventral head apodeme. In the isopods the mandible 
attains a stage almost exactly comparable with that of the higher 
pterygote insects (fig. 17 F) — the basal hinge line of the jaw^ slopes 
posteriorly and downward, and the only muscles present, so far as 
the writer could find, are the tergal abductors and adductors. 

The homologues of the mandibles in Xiphosura and Arachnida, 
the so-called pedipalps (fig. i/],Pdp), scarcely need consideration 
here. The pedipalps never attain a jaw-like form, but retain always 
the structure of a jointed limb, though the basal segment may develop 
a strong gnathal lobe. 



74 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOL. 8l 



THE FIRST MAXILLAE 



The leading features of the first maxilla have been sufficiently 
noted in the description of a generalized gnathal appendage (page 
60) based on the maxilla of Penplancta (fig. 25). In none of the 
other arthropods are the maxillary appendages so highly developed as 
in the insects, but, in all the arthropods, it appears that the mandible 
has been evolved from an appendage that was originally very similar 



Cd e 



PcR' 




Ga 



A 



B 




Fig. 30. — Maxilla of Heterojapyx gallardi. 

A, left maxilla, posterior (ventral) surface. B, right maxilla and muscles, 
anterior (dorsal) view. 

Cd. cardo ; c. articulation of cardo with cranium; ftia, flexor of galea; flee. 
cranial flexor of lacinia ; flcs. stipital flexor of lacinia ; Ga, galea ; HA, liypo- 
pharyngeal apophysis ; HS, rudiment of suspensorial arm of hypopharynx ; /, 
promotor of cardo ; KLcd, adductors of cardo ; KLst, adductors of stipes ; Lc, 
lacinia; OQ, muscle of base of palpus; p. muscle of terminal segment of palpus; 
PcR, posterior cranial ridge; Pip, palpus; iplp. first segment of palpus; St. 
stipes ; u, line of internal ridge of stipes. 

to the generalized insect maxilla. In many of the higher insects the 
maxillae, too, have become specialized, always in adaptation to special 
modes of feeding, but a description of the modifications involved is 
beyond the scope of the present paper. The musculature of the organ 
is essentially the same in all groups of biting insects, except as it 
suffers a reduction where the appendages become reduced or united 
with the labium. 

The maxilla of Japyx { fig. 30) presents a more generalized con- 
dition in its relation to the head than does the maxilla of the roach, 



NO. 3 INSECT JIEAD SNOUGKASS 75 

in that the head apophyses (B, HA) upon which the adductor muscles 
of the appendages arise are still connected with the hypopharynx, 
whereas in Periplaneta the corresponding endoskeletal arms have lost 
their primitive sternal connections and have become a part of the 
tentorium. The adductors of the cardo in Heterojapyx (fig. 30 B, 
KLcd) are well differentiated from those of the stipes (KLst), and 
cross obliquely the inner ends of the latter. The promotor of the cardo 
(/) arises against a median ridge of the dorsal wall of the cranium. 
The lacinia (Lc), which is mostly covered dorsally by the galea, has a 
broad flexor arising within the stipes (Acs), and a large cranial muscle 
{flee) arising against the dorsal cranial ridge (PeR) on the top of the 
head, and going dorsal to the other muscles of the appendage to be 
inserted on a slender apodeme from the inner angle of the lacinial 
base. The galea (Ga) is provided with a single long flexor (figs. 30 B, 
31 D, fga) arising within the stipes, which splits into two bundles of 
fibers toward its insertion on the ventral wall of the base of the galea. 
The palpus (Pip) is reduced and otherwise modified as compared with 
that of the roach (fig. 25), consisting of only three segments, of 
which the basal one (figs. 30 A. 31 D, iplp) is much elongate and is 
united with the outer wall of the base of the galea (Ga). There 
might be some question as to the homology of this basal region of the 
palpus of Japyx, but the insertion upon its base of the muscle (OQ) 
from the stipes, evidently representing the usual pair of palpal muscles, 
and the origin within it of a muscle (p) going to the distal segment of 
the palpus identify the part in question as the true basal segment of 
the palpus. 

The cardo and the stipes of many insects appear externally to be 
divided into sub-sclerites, but in most such cases it is found that the 
so-called " sutures " are but the external lines of inflections that have 
formed internal ridges, the ridges being developed either for giving 
strength to the sclerite, or to furnish special surfaces for muscle 
attachment. The cardo of Periplaneta, for example (fig. 2^A,Cd), 
has a " divided " appearance externally, but when examined from 
within (B) it is seen that the regions apparent on the surface result 
from the presence of a strong Y-shaped ridge (r) on the inner wall, 
which extends distally from the base to reinforce with its diverging 
arms the extremities of the hinge line with the stipes. This structure 
of the cardo is characteristic of other orthopteroid insects. Cranipton 
(1916) distinguishes the area of the cardo between the arms of the 
ridge as the " veracardo," and calls the rest of the sclerite the " juxta- 
cardo." The terms may have a descrijjtive convenience, but they 
are misleading if taken to signify a division of the cardo into two parts. 



76 



SAllTHSUNJAN MISCELLANEOUS COl-f.ECTIONS 



VOL. 8 1 



The stipes is usually marked by a prominent groove parallel to its 
inner edge (fig. 25 A, q), setting off a narrow marginal strip. The 
groove is here likewrise but the external line of an internal ridge or 
plate upon vi'hich are inserted the adductor muscles of the stipes 
( B, KLst) . Crampton designates the area of the stipes external to 
the ridge as the " verastipes," and that mesad to it as the " juxta- 
stipes." In Hctcrojapyx the basal part of the stipes is .strengthened 
l)y an internal ridge (fig. 30 A, u) that forks proximally to the ends 
of the hinge line with the cardo. 




Fjg. 31. — Maxillae of insects and of a chilopod. 

A, maxilla of Ncsoiiiachilis. B, maxilla of Tlicniiobia (Lepismatidae). C, 
maxilla of larva of Sialis. D, terminal part of maxilla of Hctcrojapyx. V., 
maxilla of an adnlt stonefly (Pteroiiarcys). F, first maxillae of a chilopod 
(Litliobiiis). 

Base of palpus to be identified by insertions of levato'" and depressor mnscles 
(O, Q) ; the palpifer (Plf) has no muscles, and appears as a mere subdivision 
of stipes; in Sialis larva (C). lobe is not the galea, but an endite of first 
segment of palpus {iplp), the latter identified by its muscles (O, (J). 

The ventral, or distal, end of the stipes bears the lacinia and galea, 
and to its lateral surface is attached the palpus. The lacinia and galea 
are movable lobes, each being jirovided with muscles having their 
origin in the stipes, by which they can be fiexed posteriorly (or ven- 
trally if the mouth appendages are horizontal). The lacinia, in ad- 
dition, has a muscle from the cranial wall inserted on the iinier angle 
of its base, which gives it a mesal fiection, or adduction. The base of 
the galea commonly overlaps anteriorly the base of the lacinia. 

The maxillary palpus arises from the outer wall of the stipes, 
usually only a short distance proximal to the base of the galea. The 



« 



NO. 3 INSECT HEAD SNODGRASS "JJ 

area supporting the palpus is frequently differentiated from the rest 
of the stipes, and is then distinguished as the palpifer (fig. 31 A, 
F//). When the delimiting suture of the palpifer region extends to 
the galea, the palpifer appears to support both the galea and the 
palpus. That the palpifer is not a segment of the appendage is shown 
by the fact that inuscles neither arise tinthin it nor are inserted upon 
it. The muscles that move the palpus as a whole have their origins 
within the main part of the stipes, and always pass through the pal- 
pifer, if the latter is present, to 1)e inserted on the ])roxinial segment 
of the palpus (figs. 25 C, 31 A-E, 0,0). The pal])us muscles, then, 
may be taken as identification marks of the true basal segment of the 
palpus. Since they are typically inserted one dorsally and the other 
ventrally, relative to the vertical axis of the appendage, they are 
evidently a levator ( O ) and a depressor ( ) of the palpus. The 
number of segments in the maxillary palpus varies much in different 
insects. Machilis perhaps presents the maximum number of seven 
(fig. 31 A) : the palpus of the roach with five segments is more typical 
(fig. 25). Evidence will later be given indicating that the palpus is 
the telopodite of the maxillary appendage, and that its basal articula- 
tion with the stipes, or palpifer, is the coxo-trochanteral joint of a 
more generalized limb (fig. 35 A, B, C, ct) . A joint near the middle 
of the palpus (figs. 25 C, 35 A, B. ft) often suggests the femero- 
tibial fiexvn-e. 

THE SECOND MAXILLAE 

The second maxillae of insects are unquestionably united in the 
labium. The correspondence in external relations between the parts of 
each half of a typical labial appendage and those of an entire maxilla 
is so close that most entomologists have not hesitated to assume an 
homology of the submentum (figs. 32 A, 40 D, Suit) with the cardines, 
of the mentum {Mt) with the stipites, of the glossae {Gl) with the 
laciniae, and of the paraglossal {Pgl) with the galeae. Some writers, 
however, have contended that the sul)mentum, or both the submentum 
and the mentum represent the sternum of the labial segment. Thus, 
Crampton in a recent paper (1928) adopts the idea of Holmgren 
( 1909) that the submentum and mentum arc derived from the sternum 
of the labial segment. 

In an orthopteroid labium (fig. 40 D), the muscles of the 
palpi {28, jq), and the muscles of the terminal lobes (-^5) arise in the 
mentum {Mt), and this relation, together with the presence of muscles 
from the mentum to the tentorium (i-J, 24). must certainl\- identify 
the region of the mentum in the la1)ium with that of the stipes in a 



78 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 



first maxilla (fig. 40 B, St). The wall of the mental region, however, 
may not be entirely or continuously chitinized (fig. 32 A), and, hence, 
a distinction must be drawn between the entire region of the mentum, 
and the area occupied by one or more mental sclerites. The labium 
may contain muscles not represented in the maxillae, such as the 
muscles associated with the orifice of the salivary duct in the grass- 
hopper (fig. 40 D, 26, 2/), or with the silk press in the caterpillar 
(figs. 53 C, D, 54, A, B, C, ly, 18, 19). 

The submentum corresponds functionally at least with the cardines 
of the maxillae, since it serves to attach the labial appendage to the 
walls of the head. The lateral articulation of its basal angles to the 





B 



Fig. 32. — Second maxillae. 



A, typical second maxillae of an insect (Periplaneta) united to form the 
labium. B, second maxillae of a chilopod (Lithobius) united by inner angles 
of coxae. 

ct, coxo-trochanteral joint; Cx, coxa; Gl, glossa; Mt, mentum; O, levator 
muscle of telopodite (palpus) ; Pgl, paraglossa; Pig, pelpiger; Pip, palpus; Q, 
depressor muscle of telopodite (palpus) ; Smt, submentum. 



margins of the cranium in orthopteroid insects (figs. 18 B, C, 36 C, /) 
suggests, moreover, that the points of attachment are the true 
basal articulations of the second maxillae with the cranium, corre- 
sponding with the articulations of the cardines (e) in the first maxillae. 
It is possible, of course, that a median part of the labial sternum has 
been incorporated into the submentum. To accept the proposal, how- 
ever, that the entire submentum is the sternum of the labial segment, 
is to assume that the sternum itself has become articulated laterally 
to the tergum of its segment, and that it alone bears the segmental 
appendages. Such assumed relations violate the basic principles of 
segmental inorphology, and thus throw suspicion on the evidence 
given in their support. 



NO. 3 INSECT HEAL) SNODGRASS 79 

It will be shown in the next section of this paper that the cardines 
of the maxillae are not true proximal segments of the maxillary 
appendages, but are secondary subdivisions of the bases of these 
appendages. It appears probable, therefore, that the submentum 
represents likewise proximal subdivisions of the bases of the second 
maxillae, retaining the lateral articulations with the margins of the 
cranium in generalized insects (fig. 36C, /), and perhaps including 
between them a median part of the labial sternum. 

If the insect labium (figs.< 32 A, 40 D) is compared with the second 
maxillae of a chilopod (fig. 32 B), it will be seen that the united basal 
segments of the latter {Cx), containing the origins of the palpal 
muscles {O, Q) , correspond at least with the mentum of the labium. 
The large proximal segments of the chilopod maxillae are clearly the 
bases of a generalized limb, the coxae, according to Heymons (1901), 
and the limb base, or a subcoxal division of it, bears the primitive 
dorsal articulation of the appendage with the body. The mentum, 
and at least the lateral parts of the submentum, therefore, appear to 
be subdivisions of the primary bases of the second maxillary ap- 
pendages, corresponding with the stipites and cardines of the first 
maxillae in insects, and with the similar subdivisions of the bases of 
the mandibles in the diplopods (fig. 26 A, Cd, St). 

The median, terminal duct of the labial, or " salivary," glands opens 
anterior to the labium, and, in typical forms, at the base of the mentum 
(figs. 18 D, 19, SIO). The position of the orifice, anterior to the sub- 
mentum, however, does not argue that the latter is entirely the sternum 
of the labial segment, but rather the reverse, for it is likely that the 
orifice of the duct has not left the sternal region of its segment, and 
that it has been crowded forward in the latter by the median approach 
of the labial cardines. The common duct of the lal)ial glands results 
during embryonic development from the union of the two primary 
ducts of paired lateral glands of the labial segment. 

MORPHOLOGY OF THE GNATHAL APPENDAGES 

It has often been assumed that the segmental appendages of all 
arthropods are derived from a primitive limb having a biramous type 
of structure. A two-branched limb, however, occurs actually only in 
the Crustacea, and there is no certain evidence of a biramous limb 
structure ever having prevailed in other arthropod groups. In all 
forms, including the Crustacea, the segmental appendages first appear 
in the embryo as simple protuberances of the body wall, and some 
zoologists now believe that the exopoditc branch, when present, is 



8o 



SMll'HSONIAX M1SCI:LLANE0US COLI.iaTlONS 



vol.. 8 1 



merely a specially developed exite lobe of a single shaft. Borradaile 
(191 7) expresses the opinion that " probably the primitive crustacean 
appendage resembled that of the Branchiopoda in being uniramous." 
Movable lobes individually provided with muscles, however, may be 
developed along both the outer and the inner margin of the Umb, and 
an excessive development of one of the outer lobes might give rise to 




L.: 



Fig. 33. — Parapodium and parapodial musculature of an annelid worm 
(Nereis virens). 

A, B, first and third parapodia, left, anterior surfaces. 

C, cross section of left half of a segment from middle of body, cut anterior 
to base of parapodium. showing muscles of setae inserted on end of setal 
pouch (a), and ventral promotor (A.') and remotor (L) muscles of parapodium. 
DMcl, VMcl, dorsal and ventral bands of longitudinal body muscles. 

D, musculature of third parapodium, right, inner view, showing tergal pro- 
motor (/) and remotor (7), and sternal promotor (K) and remotor (L). 

E, musculature of right side of a segment from middle of body, internal 
view, lateral oblique muscles and setal muscles removed : b, c, anterior and pos- 
terior pleuro-sternal muscles ; DMcl, part of dorsal longitudinal muscles ; /, tergal 
promotor of parapodium ; /, tergal remotor ; /, accessory remotor arising 
anteriorly from intersegmental fold ; K, sternal promotor ; L, sternal remotor ; 
.SV^ bases of setae. 



a secondary biramous structure of the appendage. Hansen (1925) 
recognizes the definitive two-branched structure of the typical crus- 
tacean appendage, but he says it seems " impossible to deny the possi- 
bility that the exopod may be analogous with the epipod, and if so 
the primitive appendage is uniramous." 

The segmental appendages, or parapodia, of the polychaete annelids 
are in some cases simple lobes ; in others they are of a two-branched 



NO. 3 INSECT HEAD SNODGRASS 8l 

structure owing to the presence of two groups of setae on each (fig. 
33 B,C). In Nereis vircns, though most of the parapodia are dis- 
tinctly cleft, those of the first and second segments do not have the 
double structure (fig. 33 A). Whatever relations, however, may be 
traced, or assumed to exist, between the annelids and the arthropods, 
the relationship must be presumed to have come through a remote 
worm-like ancestor common to both groups, for none of the highly 
organized modern annelids can be taken to represent the ancestral 
form of the arthropods. 

A comparative study of the legs of mandibulate arthropods will 
show that in each group there is a maximum of seven limb segments, 
l)eyond a subcoxal base, that are individually provided with muscles. 
The relative size and form of the segments, the character of the articu- 
lations, and the nature of the musculature present many variations, 
and it is not to be assumed that segments are to be homologized in 
all cases by their numerical order beyond the base of the limb. 

The gnathal appendages undoubtedly constitute a group of organs 
that are individually homologous in arthropod groups, whether their 
segments are united with the protocephalon to form a larger head, 
or with the body segments following. The similarity of the structure 
of the mandible in all the eugnathate arthropods, and the common 
plan of its musculature, allowing for modifications of which the 
evolution can easily be followed, leave no doubt concerning the identity 
of the jaw in the various groups, or that the jaw attained its basic 
structure in some very remote common ancestor. The primitive struc- 
ture of the mandible is not entirely preserved in any arthropod : in 
the Diplopoda and Chilopoda the movable lacinia is retained, but the 
palpus has been lost ; in the Crustacea and Hexapoda, the lacinia has 
lost its independent mobility and has become solidly fused with the 
base of the appendage, but in many crustaceans a mandibular palpus 
persists. 

The first maxilla of the Hexapoda has the structure of a generalized 
mandible, i. <?., it consists of a base supporting a palpus and at least 
one movaTjIe lobe, the lacinia, though generally there is present a 
second lobe, the galea. The insect labium consists of a pair of ap- 
pendages that probably once had the structure of the first maxillae. 
In the Chilopoda the maxillary appendages appear to have under- 
gone but little modification of structure, and those of the second 
pair still retain a form similar to that of the body appendages. The 
corresponding appendages of the Diplopoda are now so highly spe- 
cialized that it is useless to speculate as to their earlier form. In the 
Crustacea both pairs of maxillae have been reduced in size and modified 



82 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. Si 

in structure to serve as organs accessory to the mandibles, but they 
have not attained the highly specialized form of the corresponding 
appendages of insects. 

We may conclude, therefore, that in the common ancestor of the 
several groups of modern eugnathate arthropods, the mandible alone 
had attained a gnathal function, and that in form and structure it re- 
sembled the maxilla of a present day insect, though perhaps lacking 
a galea, or outer endite lobe of the base. The two maxillae at this 
period were more or less modified to serve as organs accessory to the 
mandibles. 

When the modem groups of arthropods were differentiated, the 
mandible, in the Diplopoda and Chilopoda, retained the movable 
lacinia, but lost the palpus ; in the Crustacea and Hexapoda, the lacinia 
fused with the base of the appendage to form a solid jaw, while the 
palpus was preserved by the crustaceans, and lost by the insects. The 
two maxillary appendages retained the leg-like form in the Chilopoda ; 
in the Diplopoda they became highly specialized in a manner peculiar 
to the diplopod group ; in the Crustacea and Hexapoda they were 
modified for an accessory gnathal function, but in the insects they ac- 
quired a form almost identical with that of a primitive mandible. 
Finally, in the insects, the second maxillae united basally to form the 
labium. While the insect maxilla appears to be a highly specialized 
appendage, it will be shown that its basic structure is not far removed 
from that of a thoracic leg. 

While the status of the gnathal appendages relative to one another 
in the various groups of the eugnathate arthropods seems fairly clear, 
it is a more difficult matter to homologize their parts with the segments 
of the ambulatory appendages. The structure of the first and second 
maxillae of a chilopod, or of the first maxilla of an insect, suggests 
that the gnathal appendages have been derived from an appendage 
of the ambulatory type — the insect maxilla is certainly more like the 
leg of an insect, a chilopod, or a decapod than it is like one of the 
body appendages of Apits (fig. 35 C), or of any other of the lower 
crustaceans in which the appendages are used for swimming. This 
condition suggests, therefore, that the ambulatory leg more nearly 
represents the primitive type of arthropod limb than does an appen- 
dage, such as that of Apiis, clearly modified for purposes of purely 
aquatic locomotion. If we consider, furthermore, that the appendages 
of the chelicerate arthropods (Xiphosura and Arachnida) are also of 
the ambulatory type, the evidence becomes all the more convincing 
that the primitive arthropod limb was a walking leg and not a swim- 
ming organ. If this deduction is acceptable, we must conclude that 



i 



NO. 3 



INSECT HEAD SNODGRASS 



83 



the Crustacea represent a group of arthropods that have secondarily 
adopted an aquatic life, and that, while certain forms have become 
thoroughly adapted to a free life in the water, others have retained, 
with but little modification, some of the organs that were developed 
primarily for terrestrial locomotion. This view, perhaps, is contrary 
to generally accepted ideas concerning the evolution of the arthropods, 
but it is clearly futile to attempt to derive the appendages of arth- 
ropods in general from the swimming appendages of Crustacea. 

If the ambulatory limb be taken as more nearly representative of 
the basic structure of an arthropod appendage than is the natatory 




Fig. 34.- 
malic. 



-Generalized segmentation and musculature of an insect leg, diagram- 



A, theoretical segmentation and musculature of a primitive arthropod leg, 
anterior view: the appendage, consisting of a limb base (LB), and a telopodite 
{Tip) of two segments, moved forward and backward on vertical basal axis 
{a-b) bv tergal and sternal promoters (/. K) , and tergal and sternal remotors 
U,L).' 

D, definitive segmentation of an insect leg by division of limb base (A, LB) 
into subcoxa {Sex) and coxa {Cx), and by subsegmentation of first part oi 
telopodite into trochanter and femur, and of second part into tibia, tarsus, and 
praetarsus. 

a-b, basal axis of limb base ; ct, coxo-trochanteral joint ; Cx, coxa ; F, femur ; 
ft, femoro-tibial joint; /, tergal promotor; /, tergal remotor; K, sternal pro- 
motor ; L, sternal remotor ; O, levator of telopodite ; P, tergal depressor of telo- 
podite (characteristic of insects) ; Ptar, pretarsus; Q, depressor of telopodite; 
Sex, subcoxa ; T, depressor of distal segment of telopodite ; Tar, tarsus ; Tb. tibia. 

limb, we have only to inquire as to what was its probable form in the 
ancestors of terrestrial arthropods. The primitive appendage un- 
doubtedly turned forward and backward on a vertical axis through its 
base (fig. 34 A, fl, &), as does the parapodium of a modern polychaete 
annelid (fig. 33 A, B, C). For walking purposes, however, the limb 
must have acquired joints, and, as Bonier (1921) has shown, the 
simplest practical condition would demand at least tzvo joints with 
vertical movements (fig. 34 A), one near the union of the leg with the 
body {ct), dividing the limb into a basal piece {LB) and a telopodite 



84 



SMITHSONIAX MISCELLANEOUS COLLECTIONS VOL. 8l 



(Tip), and one (ft) near the middle of the telopodite. These primary 
joints persist, evidently, as the coxo-trochanteral joint (B, ct) and the 
femero-tibial joint (ft) of the leg {Hiiftgelenk and Kniegclenk, ac- 
cording to Borner). The type of leg-segmentation resulting from 
two joints so placed applies at least to the Chilopoda, Diplopoda, 
Hexapoda, and Crustacea ; in the Xiphosura and Arachnida, however, 
it is possible that the mechanism of the leg is given by three primary 
joints, the second and third setting off a horizontal middle section 
of the leg (patella). 

The further segmentation of the limb has been produced by the 
subdivision of the principal parts of the telopodite. In the mandibu- 
late arthropods (fig. 34 B), one or two small segments cut oft' from 
the basal end of the j^roximal piece of the telopodite form the tro- 
chanters (Tr), while the rest of this part becomes the femur (F) ; 
the distal section beyond the knee joint {ft) subsegments into the 
til)ia (Tb), tarsus (Tar), and praetarsus (Ptar). This type of seg- 
mentation is clearly shown also in the maxillipeds or in any of the 
anterior body appendages of Apus. In the third maxilliped (fig. 35 
C) there are two principal flexures, one {ct) between the limb base 
{LB) and the telopodite {Tip), the other {ft) beyond the middle of 
the latter. The part between the two points of flexure is the femur 
(F) with two indistinctl}' separated trochanters {Tr) ; that beyond 
consists of two shortened segments, and the terminal praetarsus, or 
dactylopodite. The limb base of Apus is entire, but in some arthropods 
the basis appears to have become subdivided into a coxa (fig. 34 B, 
Cx) and a subcoxa {Sex). The coxa may then become the free 
fimctional base of the appendage, since the subcoxa usually forms a 
chitinization in the pleural or the sternal wall of the segment. 

The primitive musculature of the limb base was such as to swing 
the appendage forward and backward ; it must have comprised, there- 
fore, promotor and remotor muscles. Probably there was a tergal 
promotor (fig. 34 A, /) and a tergal remotor (/), and a sternal pro- 
motor {K) and a sternal remotor (L). In a thoracic leg of an insect, 
the base of the telopodite is provided with a depressor muscle (F) 
having its origin on the tergum of the segment, which greatly increases 
the lifting power of the appendage, but this muscle is not to be con- 
sidered as a primitive element of the limb musculature. The usual 
levator and depressor muscles of the telopodite {O, Q) have their 
origin within the limb base. 

The simple type of musculature shown in figure 34 A, and here 
assumed to be the primitive musculature of an arthropod limb base, 
is actuallv present in typical form in the simpler anterior parapodia 



NO. 3 INSECT HEAD SNODGRASS 85 

of the annelid, Nereis virens (fig. 33 D). Here a dorsal proniotor 
and a remoter (/, /) arise on the tergal wall of the segment, and a 
ventral promoter and a remotor {K, L) on the midline of the sternal 
wall. The ventral muscles are repeated regularly in all the segments 
of the worm (C, E, K, L), but in the more posterior segments the 
dorsal muscles, though present (E, I, J), are less symmetrical in ar- 
rangement, and the primary remotor (/) is subordinated to a large 
oblique remotor (/) that arises on the anterior margin of the seg- 
ment. This last muscle is described by Borner (1921) as being the 
typical dorsal remotor of the parapodium, but by comparison with the 
simpler anterior appendages (D) it appears to be a secondary acquisi- 
tion, for the muscle (E, /) dipping beneath it has the same insertion 
on the parapodial base as that of the tergal promoter of tlic anterior 
parapodium (D, /). Borner's claim, however, that this simple type of 
limb musculature presented by Nereis must represent the primitive 
motor mechanism of an appendage turning forward and backward on 
a vertical axis through its base is scarcely to be questioned. 

The basal muscles of an appendage do not necessarily retain their 
original functions, nor their primitive simplicity, for an alteration in 
the basal articulation of the appendage may change the fundamental 
movements of the limb, and thereby give quite a different action to 
the muscles, which, in turn, may shift in position, or become split up 
into segregated groups of fibers, thus multiplying the number of in- 
dividual muscles actually present. 

Returning now to a further consideration of the muscles of the 
gnathal appendages of the arthropods, it is not difficult to draw a 
parallel between the musculature of a mandible, or of an insect 
maxilla, and that of the annelid parapodium (fig. 33D, E), or with 
the hypopthetically primitive musculature of an arthropod limb base 
as expressed in figure 34 A. In the mandible of Scutigera (fig. 26 B, 
C), Apus (fig. 27 A), Hetcrojapyx (fig. 27 C), Ncsomachilis (fig. 
27 D), a tergal promoter (/) and a remoter (/) have the typical re- 
lation to the appendage. In some forms the tergal remotor appears 
to be lacking (Diplepeda, fig. 26 A; Spiroiitocaris, fig. 27 B). The 
cranial flexor of the mandibular lacinia m diplopods and chilopods 
(fig. 26 A, B, C, iJcc) is probably derived from the tergal promoter, 
since it arises en the dorsal wall of the head and goes dorsal (an- 
terior) to the ventral muscles. The sternal promoter and remotor, 
which are distinct muscles in the annelid parapodium (fig. 33 C, D, E, 
K L), are united in the gnathal appendages of the arthropods, where 
they become ventral adductors (A'L) as a result of the free movement 



86 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8 1 

of the base of the appendage on a single dorsal point of articula- 
tion (a). 

The adductor fibers of the mandible may all retain their connection 
with the sternal, or hypopharyngeal, apophyses (Chilopoda, fig. 21 B), 
or they may become detached from the apophyses and united with the 
fibers from the opposite jaw to form a transverse dumb-bell muscle 
(Diplopoda, fig. 26, A, KL; some Crustacea, fig. 27 A, B ; most 
Apterygota, fig, 27 C, D, KLk), though at the same time some of 
the fibers may retain their connections with the apophyses, or with 
the tentorium (Apterygota, fig. 27 C, D, KLt; Orthoptera, fig. 29 C, 
KLt) or with the base of the hypopharynx (Lepisma, fig. 29 B, KLh ; 
Locusta, fig. 29 C, KLh ; Microcentrum, fig. 20 D, KLh ; ephemerid 
nymph, fig. 20 A, KLh). The evolution of the mandibular muscles in 
the higher insects has been detailed in an earlier paragraph, wherein it 
was shown that the ventral adductors are reduced and finally obliterated 
after the jaw has acquired a double hinge with the edge of the cranium, 
and that the tergal promotor and remotor muscles then become respec- 
tively the functional abductors and adductors. 

The basal musculature of the insect maxilla, as already shown, 
coincides almost exactly with the basal musculature of the mandible 
of a diplopod or a chilopod, and may be derived from the simple plan 
of the musculature of the annelid parapodium. The tergal promotor 
is evidently separated into two groups of fibers inserted on the dorsal 
and ventral extremities of the anterior rim of the appendage base, 
the upper set being the muscle of the cardo (figs. 25 C, 30 B, 7), the 
lower set the cranial flexor of the lacinia {Hcc). A tergal remotor is 
lacking in the insect maxilla, but so it appears to be also in the diplopod 
mandible (fig. 26 A). The sternal promotor and remotor muscles (figs. 

33 D, E, 35 B, i<^, L) are united, as in the mandible, to form a ventral 
adductor (KL), the fibers of which almost always retain their origin 
on the hypopharyngeal apophyses, or on the corresponding part of 
the tentorium, and are distributed to both the cardo and the stipes 
(figs. 25 C, 30 B, KLcd, KLst) . In Machilis the maxillary adductors 
from opposite appendages are united with each other medially, and 
appear to be detached from the ventral apophyses. 

The margin of the basal cavity of the maxilla (fig. 35 A) includes 
the region of the cardo, the stipes, and the lacinia ; and the tergal 
and sternal muscles (/, /, KL) of the appendage are distributed to 
these three parts. The entire base of the maxilla, therefore, has the 
fundamental character of a single segment, and there can be no doubt 
that this segment is the true primitive base of the appendage (fig. 

34 A, LB) . The base of a leg appendage may be divided into a coxa 



NO. 3 



INSECT HEAD SNODGRASS 



87 



and a subcoxa (fig. 34 B, Cx, Sex), and Borner (1909, 1921) would 
identify the cardo of the maxilla with the subcoxa of a leg. The suture 
separating the cardo from the stipes, however, terminates at both 
ends in the marginal rim of the maxillary base (fig. 35 A) instead 
of running parallel with it; the cardo, therefore, does not have the 
relation of a true segment to the rest of the appendage. It is perhaps, 




Fig. 35. — The relation of a maxilla to a generalized limb. 

A, theoretical generalized structure of a gnathal appendage, consisting of a 
limb base (LB), bearing a divided basendite (Lc, Ga), and a six-segmented 
telopodite, or palpus (Pip), with the principal downward flexure at the femoro- 
tibial joint (ft). The limb base provided with tergal promotor and remotor 
muscles (/, /), and sternal adductors (KL). 

B, showing basal musculature of a gnathal appendage analysed into the 
functional elements of the musculature of an annelid parapodium (fig. 33 D). 

C, third maxilliped of Apus longicaxidata, left, anterior surface, showing 
division into a limb base (LB) and a telopodite (Tip) ; the base movable on a 
transverse axis (a-b), the telopodite with a principal flexure (ft) between its 
third and fourth segments. 

a-b, basal axis of limb base; Be, basendite; ct, coxo-trochanteral joint; F, 
femur ; fga, flexor of galea ; flee, cranial flexor of lacinia ; flcs, stipital flexor of 
lacinia; ft, femoro-tibial joint; Ga, galea; /, tergal promotor; /, tergal 
remotor; K, sternal promotor; KL, ventral adductors (K and L united); L, 
sternal remotor ; LB, limb basis ; Le, lacinia ; O, levator of telopodite ; Pip, 
palpus (telopodite) ; Q, depressor of telopodite; Tip, telopodite; Tr, trochanters. 



though, to be questioned if the subcoxa! chitinization, the pleuron, at 
the base of a thoracic leg is not also a mere subdivision of the basal 
limb segment similar to the cardo, rather than the remains of a true 
independent segment. If the cardo does, in any sense, represent the 
thoracic subcoxa, it is to be noted that the hinge line between it and 
the stipes has a horizontal position with reference to the axis of the 
appendage, and this, the writer has argued (1927), must have been 
the primitive position of the subcoxo-coxal hinge in a thoracic leg. 



88 



SMITHSONIAN MISCFXLANEOUS COLLECTIONS VOL. 8l 



Though the homology of the cardo must be left in question, the 
writer would agree with Borner (1909, 1921) that the part of the 
maxilla bearing the lacinia, galea, and palpus represents the coxal re- 
gion of the leg base, and that the basal segment of the palpus is a tro- 
chanter (fig. 35 A, Tr). The lacinia and galea, then, are coxal endites, 
and, as Borner proposes, the stipes and palpifcr arc corresponding sec- 
ondary subdivisions of tJic coxa, or of the coxal region of the maxillary 
base. In the maxillae and maxillipeds of the Crustacea, Borner 
claims, the segments bearing the lobes homologous with the insect 
lacinia and galea are also subdivisions of the coxa. By this interpre- 
tation, the palpus (fig. 35 A, Pip) becomes the telopodite of the maxil- 
lary appendage (B) ; its basal union with the stipes or palpifer is the 
coxo-trochanteral joint (ct), and its principal distal articulation hav- 
ing a ventral flexure is the femoro-tibial joint (ft). 

Other writers have held somewhat divergent views concerning the 
homologies of the maxillary segments. Goldi (1913) interpreted the 
cardo as the coxopodite, the stipes as the basipodite, to which he 
assigned the lacinia and galea as endite lobes, and the basal segment 
of the palpus as the ischiopodite. Crampton (1922) gave a modifica- 
tion of this view in that he proposed that the palpifer represents a 
segment, the ischiopodite. and that the galea is an endite of this seg- 
ment. Uzel (1897) appears to give confirmation to this view in his 
description of the development of the maxilla of Campodea ; the maxil- 
lary rudiment, he says, is first divided into an outer and an inner lobe, 
and then the outer lobe splits into two parts, one of which becomes 
the palpus, the other the galea. If the maxilla of Campodea resembles 
that of Japyx (fig. 30 A), however, it is easy to believe that the 
structure in the embryo might be misinterpreted, in as much as the 
adult structure is misleading until the muscle relations are taken into 
consideration (fig. 31 D) ; then it is seen that the basal region of the 
palpus, which is united with the base of the galea, is the true basal 
segment of the palp, and not the palpifer — clearly a secondary modi- 
fication. 

It has already been pointed out that the entire lack of muscle con- 
nections in the palpifer is a condition that disavows the segmental 
nature of the palpifer region. Crampton's best example among in- 
sects of a structure corresponding- with his idea of the segmentation 
of a maxillary appendage is the maxilla of the larva of Sialis (fig. 31 
C), in which there is a small lobe (o) borne on the apparent first seg- 
ment of the palpus. This lobe Crampton would identify as the galea, 
making the supporting segment the palpifer. The muscles (O, Q) in- 
serted on the base of this segment, however, clearlv demonstrate that it 



NO. 3 INSECT HEAD SNODGRASS 89 

is the true base of the palpus {iplp) — therefore, not the palpifer. 
which lacks muscles — and that the lobe in question is not the galea, 
as also the absence of a muscle to it would indicate. The maxilla of 
the Sialis larva, then, is not a generalized appendage in the sense that 
Crampton would infer, since it lacks a true galea and is provided with 
an accessory lobe on the first segment of the palpus. Similar lobes 
of the palpus segments occur in other insects, particularly in larvae 
of Coleoptera ; they have a suggestion of the endite lobes of the telo- 
podite in such crustaceans as Apus (fig. 35 C). 

In the thoracic legs the limb is always flexible at the union between 
the basis and the telopodite, i. e., at the coxo-trochanteral joint, and 
in no appendage, where the facts can be clearly demonstrated, is 
there a union between the coxa and the trochanter. It does not seem 
reasonable, therefore, to suppose that the proximal segment of the 
telopodite (the trochanter) should have been incorporated into the 
limb base in the case of a maxillary appendage. Especially is such 
a supposition unreasonable in the face of nnich specific evidence to 
the contrary. The whole body of evidence l)earing on the limb mech- 
anism points to a primitive uniformity of flexure in all the appen- 
dages, whereby the limb is divided into a basis and a telopodite. and 
indicates that the articulation between these two parts is preserved in 
the entire series of appendages, except, of course, where the telo- 
podite is lost. 

The maxillipeds and the anterior body appendages of Apus bear 
each five endite lobes. The first lobe (fig. 35 C, Be) is a basendite, 
the second is carried by the proximal division of the trochanter, the 
third by the femur, the fourth by the tibia, and the fifth by the tarsus. 
Each endite is independently movable by muscles inserted upon or 
within its base. The maxillae of Apus are reduced to single lobes, but 
the first maxilla appears to represent the rudimentary limb base with 
the large basendite, since it falls exactly in line with the series of 
basal endites on the following appendages. The basal endites of 
arthropod limbs in general, including the " gnathobases " of the trilo- 
liite appendages, the gnathal lol)es of the pedipalps in Xiphosura and 
Arachnida, and the " styli " of the legs of Scolopendrella, are almost 
certainly analogous lobes in all cases, and they must be represented 
by the laciniae (at least) of the insect maxillae, by the laciniae of the 
mandibles of diplopods and chilopods, and by the incisor and molar 
lobes of the mandibles in all arthropods. It is a question, therefore, 
whether the galea of the insect maxilla is an accessory lobe of the 
limb base, or a subdivision of the primary basendite (fig. 35 B, C, Be) 
The latter seems probable, since, in the more generalized insects, the 



90 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

lacinia and galea overlap each other basally, and both are flexed by 
the muscles inserted upon their bases that have their origin in the 
stipes. 

It is impossible at present to arrive at final conclusions on the many 
problems connected with the morphology of arthropod appendages, 
and the most that the writer would claim for the present attempt at 
advancing the subject is that the material here presented gives at 
least a substantial enlargement to the foundation of known facts from 
which future work must proceed. There is no question that students 
of arthropods have given far too little attention to the relationship 
between skeletal structure and musculature. The more the svibject is 
looked into, the more it will be seen that the characters of the arthropod 
skeleton are in large part adaptations to the strain of muscle tension, 
and that they are to be correctly interpreted only through an under- 
standing of the entire mechanism of which they are a part. The 
sclerites of the insect cuticula, in particular, have been studied as if 
they were skeletal elements deftly fitted together in such a manner as 
to cover the outside of the animal, and we entomologists have played 
with them, as we might with the sections of a picture puzzle, without 
looking for their significance in the mechanics of the insect. The 
arthropod skeleton, it is true, has been formed from a few major 
centers of increased chitinization, but the minor " divisions " are in 
almost all cases adaptations to flexion, or the opposite, namely, the 
strengthening of the skeleton by the development of internal ridges. 
The scientific study of the comparative anatomy of insects must look 
for its advance in the future to a wider knowledge of muscles and 
mechanism. 

IV. SUMMARY OF IMPORTANT POINTS 

I. The arthropods have been derived from creeping animals, not 
from forms specially modified for swimming ; their immediate pro- 
genitors were annelid-like in structure. 

^2. The stomodeum marks the anterior end of the blastopore. There 
are, therefore, no true mesodermal segments anterior to the mouth. 
The unsegmented preoral part of the animal is the prostomium, and 
constitutes the most primitive head, or archkephalon, of segmented 
animals, since it contains the first nerve center, or " archicerebrum," 
and bears the primitive sense organs. 

3. The first stage in the development of a composite head in the 
arthropods, as represented in the embryo, comprises the prostomium 
and the first two or three postoral segments. The head in this stage 
may be termed the protocephalon; it is represented by the cephalic 
lobes of the embryo, which may or may not include the third segment. 






NO. 3 INSECT HEAD SNODGRASS QI 

4. The protocephalon carried the labrum, the mouth, the eyes, the 
preantennae, and the antennae, also the postantennae when it included 
the third body segment. 

5. During the protocephalic stage of insects, as shown by the em- 
bryo, the thorax was differentiated as a locomotor center of the body, 
and the region between the head and the thorax, consisting of the 
fourth, fifth, and sixth body segments, became a distinct gnathal 
region. 

6. The gnathal region was eventually added to the protocephalon to 
form the definitve head, or telocephalon. In the Crustacea, in which 
there was no thoracic region corresponding with that of the insects, 
the gnathal region was not definitely limited posteriorly, and the 
definitive head in this group may include as many as five segments 
following the protocephalon. In some of the crustaceans the gnathal 
segments have united with segments following to form a gnatho- 
thorax, leaving the protocephalon as a separate anterior head piece. 
In the Arachnida the protocephalon included the prostomium and two 
postoral metameres, and it has combined with the following six seg- 
ments to form the cephalothorax. 

7. In the definitive insect head, the prostomium, according to some 
embryologists, contril)utes the clypeus and frons and the region of 
the compound eyes ; according to others it forms the clypeus and 
frons only. The labrum is a median preoral lobe of the prostomium. 

8. The arthropod brain probably always includes the median pro- 
stomial ganglion, combined with the ganglia of the preantennal segment 
to form the protocerebral lobes. It may still be questioned whether 
the optic lobes are derived from the prostomium or from the prean- 
tennal segment. The ganglia of the antennal segment form the deuto- 
cerebrum. The commissures of the protocerebrum and the deutocere- 
Ijrum are formed above the stomodeum, and unite with the archicere- 
bral rudiment to form the median part of the brain. The ganglia of 
the postantennal segment, when united to the preceding ganglia, 
become the tritocerebral brain lobes, but they, remain separate from 
the brain in some crustaceans, and their uniting commissure always 
preserves its sub-stomodeal position. 

9. The prostomial region of the adult arthropod is innervated from 
the postantennal ganglia, but this is probably a secondary condition 
owing to the loss of the true prostomial nerves. 

10. The appendages of the definitive insect and myriapod head are 
the preantennae, the antennae, the postantennae, the mandibles, the 
first maxillae, and the second maxillae. Rudimentary, evanescent 
preantennae have been reported only in the embryo of Scolopcndra 



92 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

(Heymons) and in the embryo of Carausius (Wiesmann). Postan- 
tennae are commonly present in insect embryos, but their rudiments 
persist in only one or two doubtful cases in the adult. The postantennal 
appendages are the second antennae of Crustacea, and probably the 
chelicerae of Arachnida and Xiphosura. Endites of their bases may 
have been the functional jaws of the insectan and myriapodan an- 
cestors in the protocephalic stage. 

11. The gnathal appendages have been derived from organs having 
the structure of uniramous ambulatory legs. All the primitive ar- 
thropod appendages were probably uniramous ambulatory limbs. Bira- 
mous and natatory appendages are characteristic of the Crustacea only, 
and are probably secondary adaptations to an aquatic life. 

12. The mandible is a common inheritance from an early ancestor 
of the eugnathate group of arthropods. Its primitive structure re- 
sembled that of the first maxilla of modern insects, and is best pre- 
served in the Myriapoda. 

13. The diplopod mandible consists of a base subdivided into cardo 
and stipes, bearing a large movable lacinia. but lacking a galea and a 
palpus. In the typical chilopod mandible, the division between cardo 
and stipes has been lost, and the lacinia is less free. The musculature 
of the chilopod mandible is more primitive than that of the diplopod 
mandible. In the crustaceans and insects the mandibular lacinia is 
either lost, or is fused with the base to form a solid jaw. The mandib- 
ular palpus is retained in many Crustacea. The mandible is repre- 
sented by the pedipalp in Arachnida. 

14. The first maxillary appendage is best developed in the insects, 
and probably here preserves the primitive structure of the mandible. 
Its musculature is exactly duplicated in the musculature of the man- 
dibles in the diplopods and chilopods. Neither the first nor the second 
maxillae of the chilopods gives any evidence of ever having at- 
tained the special structure of the primitive mandibles and the insect 
maxillae. 

15. A primitive gnathal appendage had the structure of a gener- 
alized ambulatory appendage, consisting of a liinh basis and a fclo- 
poditc. The basis represents the coxa and subcoxa of a thoracic leg, 
but its division into cardo and stipes is not a true segmentation. The 
galea and lacinia are movable endites of the basis, with the origin 
of their muscles in the stipital region of the latter. The telopodite 
becomes the palpus of the gnathal appendage, and its basal articula- 
tion is the homologue of the coxo-trochanteral joint in the leg. The 
palpifer is not a segment of the limb, but a subdivision of the stipes 



NO. 3 INSECT HEAD SNODGRASS ()3 

bearing the palpus and the galea (as claimed by Borner) ; the muscles 
of the palpus and the galea pass through the palpifer, but never arise 
within it. 

i6. The primitive appendage was implanted in the soft lateral wall 
of its segment, and turned forward and backward on a vertical axis 
through its base, as does an annelid parapodium. The first joint set 
off the telopodite, and gave the latter a mobility in a vertical ])lane. 

17. The primitive muscles inserted on the base of a generalized limb, 
as on an annelid parapodium, consisted of a dorsal promotor and a re- 
motor, and of a ventral promotor and a remoter. When tergal plates 
were developed, the gnathal appendages of the arthropods became 
attached to their lateral margins, each by single point of articulation. 
The ventral muscles of the appendages then became sternal adductors. 

18. The points of origin of the ventral adductors of the gnathal 
appendages in myriapods and insects were probably crowded together 
when the gnathal segments were added to the protocephalon. They 
have since become supported on a pair of apophyses arising at first 
from the base of the hypopharynx. In the myriapods and in most of 
the apterygote insects, the apophyses still maintain their hypopharyn- 
geal connections : but in the pterygote insects their l)ases have migrated 
laterally to the margins of the cranium, and in all but some of the 
lower forms have finally moved to a facial position in the epistomal 
suture. Their posterior ends have united with the transverse ten- 
torial bar developed in the back part of the head. The hypopharyngeal 
apophyses of the Myriapoda and Apterygota have thus come to be 
the anterior arms of the pterygote tentorium. 

19. The adductor muscles of the insect maxillae, arising on the 
tentorium, are the sternal adductors of the appendages, corresponding 
with the sternal adductors or rotators of the thoracic legs, and are 
derived from the primitive ventral promoters and remotors of the 
limb. 

20. The ventral adductors of the mandibles in the Chilopoda re- 
tain their connections with the sternal, or hypopharyngeal, apophyses. 
In the Diplopoda, Crustacea, and Apterygota, groups of the adductor 
lil)ers from the mandibles have lost their sternal connections and have 
united with each other by a median ligament to form a dumb-bell 
muscle between the two jaws. Other groups of fibers may retain their 
connections with the apophyses, or direct with the base of the hypo- 
I)harynx. In the Pterygota, the ventral adductors of the mandibles have 
been lost, except for a few rudiments in some of the lower orders. 

21. The mandible of Lcpisma and of pterygote insects is hinged 
to the head on a long base line with anterior and posterior articulations. 



94 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

The posterior articulation is the primitive one, the anterior a secon- 
dary one. By this change in the articulation and movement of the 
jaw, the primitive tergal promotor muscle becomes an abductor, and 
the primitive tergal remotor becomes an adductor. The base line of 
the mandible slopes downward and forward in Lepisina and in a few 
of the lower pterygotes ; in all others its slope is reversed, allowing 
the tip of the jaw to swing inward and posteriorly during adduction. 
A similar evolution of the mandible has taken place in the Crustacea. 
22. The ridge of the base of the insect cranium, on which the pro- 
thoracic and neck muscles are inserted, is probably a chitinization of 
the intersegmental fold between the maxillary and labial segments. 
The posterior tentorial arms arise from its ventro-lateral ends by in- 
vaginations in the external suture. The neck of the insect, therefore, 
may be unchitinized parts of both the labial and the prothoracic 
segments. 

V. THE HEAD OF A GRASSHOPPER 

After laying down the general principles worked out in the pre- 
ceding sections, it will be well to test them with a few specific examples. 
The head of a grasshopper is a good subject for an elementary study 
of the structure of the pterygote insect head, because it preserves the 
generalized orientation in having the face directed forward and the 
mouth appendages hanging downward. Terms of direction, therefore, 
do not have to be qualified — ventral is downward, dorsal is upward, 
and anterior is forward. The descriptions here given are based on 
the Carolina locust (Dissosteira Carolina), a fairly large grasshopper 
to be obtained in almost any part of the United States. 

The muscles are designated numerically for convenience of refer- 
ence only, and the same numbers do not refer to corresponding muscles 
in the grasshopper and in the caterpillar (Section VII) . The myology 
of insects is as yet too little advanced to furnish a satisfactory general 
nomenclature for insect muscles, and no attempt is made here to use 
a set of names for the muscles of the grasshopper that could in all 
cases be applied to the muscles of other insects. The usual method of 
naming muscles according to their function, or their supposed func- 
tion, gives terms fitting for the species described; but in many cases, 
by a change in the articulation between the skeletal parts involved, 
muscles that are clearly homologous have their functions completely 
altered. Again, it is impossible to name muscles consistently according 
to their points of origin and insertion, for either end of a muscle may 
shift and may migrate into a territory quite foreign to its original 



NO. 3 



INSECT HEAD SNODGRASS 



95 



connections. A third feature disturbing to a uniform muscle nomen- 
clature is the fact that any muscle may break up into groups of fibers, 
or, at least, a single muscle in one species may be represented func- 
tionally by several muscles in another. Finally, there are muscles that 
are evidently new acquisitions developed in connection with special 
mechanisms. The importance of the study of musculature for the 
understanding of the insect skeleton, however, can not much longer 
be ignored. 

STRUCTURE OF THE CRANIUM 

The walls of the head in the grasshopper are continuously chitinized 
on the anterior, dorsal, and lateral surfaces (fig. 36 A, B), and the 



Ant Vx ocs Oc 




Fig. 36. — Head of a grasshopper, Dissosteira Carolina. 

A, lateral. B, anterior. C, posterior. 

a, posterior articulation of mandible; Ant, antenna; at, anterior tentorial pit; 
r, anterior articulation of mandible; Clp, clypeus ; cs, coronal suture; cv, cervical 
sclerites ; E, compound eye ; c. articulation of maxilla with cranium ; cs, epistomal 
suture; /, articulation of labium with cranium; For, foramen magnum ;_ /.y, 
frontal suture; g. condyle of postocciput for articulation with cervical sclerite; 
Gc, gena ; h, subocular ridge ; /, frontal carina ; ;, subantennal suture ; k, flexible 
area between lower edge of gena and base of mandible ; Lb, labium ; Lm, labrum ; 
Md, mandible; Mx, maxilla; O, ocellus; Oc, occiput; ocs, occipital suture; 
Pgc, postgena ; Poc, postocciput ; PoR, postoccipital ridge ; pos, postoccipital 
suture ; PT, posterior arm of tentorium ; pt, posterior tentorial pit ; sgs, subgenal 
suture ; Vx, vertex. 

dorsal and lateral walls are reflected upon the posterior surface (C) 
to form a narrow occipito-postgenal area surrounding the foramen 
magnum (For). The foramen is closed below by the neck membrane, 
in which is suspended the base of the labium (Lb). The ventral wall 
of the head, between the bases of the gnathal appendages, is occupied 
inostly by the large median hypopharynx, it being otherwise reduced 
to the narrow membranous areas between the lateral margins of the 
hypopharynx and the bases of the mandibles and maxillae. 



96 SMITHSONIAN MTSCl'lLLANEOUS CULI.ECTIONS VOL. 8[ 

The facial aspect of the cranium is distinctly separated by the 
epistomal suture (fig. 36A, B, r^-) from the clypeus, but there is no 
demarked frontal sclerite. The apex of the f rons, however, is defined 
in Dissostcira by two short remnants of the frontal sutures (B, fs) 
diverging- from the end of the coronal suture (cs). The facial area 
of the head is limited on each side by an impressed line (/{) extending 
from the lower angle of the eye to the anterior articulation of the 
mandible. The median part of this area forms a broad frontal cosfa, 
margined laterally by a pair of sinuous carinae (/') reaching from the 
top of the head to the lower part of the face. A short, transverse 
suhantcnnal suture (j) lies on each side of the frontal costa just 
below the level of the median ocellus. The inner ridges of these 
subantennal sutures have a close relation to the attachments of the 
more important muscles of the frons (fig. 38 D, ;'). The true frontal 
area of the grasshopper, therefore, must include the region of these 
sutures and extend dorsal to them between the bases of the antennae 
into the angle between the short remnants of the frontal sutures. 

The lateral areas of the head (fig. 36 A) have no special character- 
istics. The subgenal suture (sgs) on each side is continuous anteriorly 
with the epistomal suture (es). The compound eye is surrounded by 
a distinct suture forming a high ridge internally (fig. 39 A, OR), and 
setting oft" a narrow rim, or ocular sclerite, around the base of the 
eye (fig. 36, A, B, C). 

On the posterior surface of the head (fig. 36 C), the occipito- 
postgenal area (Oc, Pge) is included between the well-marked occip- 
ital suture {ocs) and the postoccipital suture {pos). In Dissosteira 
the occiput and postgenae are continuous ; in Mclanoplus the occipital 
arch is separated from the postgenae by a short groove on each side 
on a level with the lower angles of the compound eyes. Posterior 
to the postoccipital suture is the postoccipital rim of the head (Poc), 
widened above and below on each side, to which the membrane of the 
neck is attached. The postoccipital suture forms internally the ridge 
on which the muscles of the neck and prothorax that move the head 
are inserted (fig. 45 A, PoR). Laterally the postoccipital ridge is 
elevated as a high plate (fig. 36 C,Fo/?), from the ventral ends of 
which the posterior arms of the tentorium (PT) proceed inward. The 
roots of the tentorial arms appear externally as long open slits in the 
lower ends of the postoccipital suture (pt, pt). 

The clypeus and labrum form together a broad free flap (fig. 36 A, 
B, Clp, Lni) hanging before the mandibles from the lower edge of the 
frontal region. The fronto-clypeal, or epistomal, suture (es) is a 
deep groove forming internally a strong epistomal ridge (fig. 39 A, 



k 
Ml 



NO. 3 



INSECT IIEAl 



-SNODCKASS 



97 



B, C, ER), from the lateral parts of which arise the anterior tentorial 
arms {AT). The roots of these arms appear externally as lateral 
slits in the epistomal sutm-e (figs. 36 B, 37 A, at, at), just mesad 
to the anterior articulations of the mandibles {c, c). The clypeus of 
Dissostcira is partially divided by transverse lateral grooves into 
anteclypeal and postclypeal areas. The labrum is a 1)road oval plate, 
notched at the middle of its ventral margin, freely movable on the 
lower edge of the clypeus. A median quadrate area on its basal half 
is limited below by a sinuous transverse groove (fig. 37 A) that forms 
a low ridge on the inner surface of the anterior wall (B, /.) On the 




AT 



Clp— 



-Lm— 




Tor 



A 



B 



Fig. 2)7- — Clypeus and labrum of Dissostcira Carolina. 

A, anterior surface. B, posterior surface of anterior wall, showing muscle 
attachments, and bases of anterior tentorial arms. 

AT, anterior arm of tentorium; at, anterior tentorial pit; c", anterior articula- 
tion of mandible ; Clp, clypeus ; es, epistomal suture ; /, ridge of anterior labral 
wall; Lm, labrum; Tor, torma ; /. labral compressors; ^, anterior retractors of 
labrum; 3, posterior retractors of labrum; 34, 35, points of origin of anterior 
dilators of buccal cavity (figs. 41, 44). 

posterior surface of the clypeo-labral lobe, the area of the clypeus is 
separated from that of the labrum by two small chitinous bars, the 
tonme (figs. 37 B, 42 A, Tor). A median Y-shaped thickening (fig. 
42 A, 7/0 of the cuticula of the labrum makes a ridge on the inner 
surface of the posterior labral wall. 

The clypeus has no muscles for its own movement, but the first 
two pairs of anterior dilators of the buccal cavity (figs. 41, 44, 33^ Si) 
are inserted on the inner surface of its anterior wall (fig. 37 B, jj, 
34) . The labrum is provided with three sets of muscles, as follows : 

I.— Compressors of the labrum (fig. 37 B).— A pair of short mus- 
cles arising medially on transverse ridge of anterior labral wall (/) ; 
diverging to arms of Y-shaped ridge in posterior wall (fig. 42 A. m). 



98 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 81 

2. — Anterior retractors of the labrum (fig. 37 B). — A pair of long 
muscles arising on subantennal ridges of frons (fig. 38 D, ;") ; con- 
verging downward to insertions on base of anterior wall of labrum 
(%-37B). _ 

J. — Posterior retractors of the labrum (fig. 37 B). — A pair of long 
muscles arising on subantennal ridges of frons, each laterad of 2 (fig. 
38 D) ; inserted on dorsal processes of tormae at base of posterior 
wall of labrum (figs. 37 B, 42 A). 

The articulations of the gnathal appendages occupy typical positions 
along the lower lateral margins of the cranium. The mandible articu- 
lates anteriorly with a condyle (fig. 39 A, c) supported at the junction 
of the epistomal and subgenal ridges {ER, SgR), but projecting on 
the external surface of the head. Posteriorly the jaw articulates with 
a facet on the ventral edge of the postgena (figs. 36 C, 39 A, C, a). 
This articulation as the first is outside the membranous connection 
of the mandible with the head. The axis of the mandible slopes 
strongly downward and posteriorly between the articular points. The 
lateral edge of the mandibular base is separated from the margin of 
the gena by a narrow, flexible strip of weakly chitinized articular 
membrane (fig. 36 A, k), at the ventral margin of which arises the 
abductor apodeme of the mandible (fig. 39 D, 8 Ap). 

The maxilla articulates by a single point on the base of the cardo 
with a shallow facet on the edge of the postgena (figs. 36 C, 40 C, c) 
almost directly below the posterior tentorial pit {pt). The maxillary 
articulation is thus crowded unusually far posteriorly in the grass- 
hopper. In most generalized insects it lies well before the line of the 
postoccipital suture, as in a roach or a termite, and is often mucli 
farther forward. 

The labium is loosely articulated by the elongate basal angles of tbe 
submentum with the posterior margin of the postocciput at points a 
short distance above the posterior lower angles of the latter (figs. 36 
C, 40 C, /). 

The tentorium of the grasshopper has the form of an X-shaped 
brace between the lower angles of the cranial wall (fig. 39 B). The 
anterior arms {AT) arise from the lateral parts of the epistomal ridge 
(ER), their broad bases extending from points above the mandibular 
articulations half way to the median line of the face. In this respect 
Dissosteira shows an advance over Periplaneta. in which the bases of 
the anterior tentorial arms arise from the subgenal ridges and extend 
only a short distance mesad of the mandibular articulations. 'V\v 
posterior tentorial arms of Dissosteira (fig. 39 B, PT) arise from the 
lower ends of the postoccipital ridge (fig. 45 A. PoR). The median 



NO. 3 



INSECT HEA 



SNODGRASS 



99 



body of the tentorium is concave below (fig. 39 B, C, Tnt). A thin, 
flat dorsal arm of the tentorium (fig. 39 C, DT) arises from the base 
of the inner end of each anterior arm and extends upward and anter- 
iorly to the wall of the cranium just before the lower angle of the 
compound eye. The dorsal tentorial arms are attached to the hypo- 
dermis of the head wall, but make no connection with the cuticula 
in Dissosteira. 

THE ANTENNAE 

Each antenna consists of two larger basal segments, and of a long 
slender flagellum broken up into about 24 small subsegments. In 




4a 




ii\ ^-tb ER 



D 



Fig. 38. — Antenna of Dissosteira Carolina and of Periplaneta. 

A, base of left antenna of Dissosteira, ventral surface. B, the _ same _ of 
Periplaneta. C, base of right antenna and antennal muscles of Dissosteira, 
dorsal view. D, base of right antenna, antennal muscles, anterior tentorial arm, 
muscles arising on frons, and associated structures of Dissosteira, interior view. 

SAp, apodeme of depressor muscles of antenna; AR, antennal ridge; At, 
anterior arm of tentorium ; c, anterior articulation of mandible ; DT, dorsal 
arm of tentorium; ER, epistomal ridge; es, epistomal suture; ;, subantennal 
ridge; n, pivot of antenna; OR, ocular ridge; Pdc, pedicel; Sep, scape. 

Dissosteira the antenna of the male is a little longer than that of 
the female. Of the two basal segments, the proximal one, or scape 
(fig. 38 A, Sep), is the larger. It is articulated to the rim of the 
antennal socket by a small process on the lateral ventral angle of its 
base that touches upon the margin of the socket {n). The motion of 
the scape on the head, however, is that of a hinge joint moving in a 
vertical plane on a transverse axis. The base of the scape is provided 



]00 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

with levator and depressor muscles (C, D). In other insects the 
antenna is more commonly pivoted on a ventral point of articulation 
with the rim of the socket, as in Periplaneta (fig. 38 B, n), and thus has 
greater freedom of movement. As already noted, how^ever, the artic- 
ular point may be dorsal, as in Japyx, and in the Chilopoda (fig. 23 
B, n). The thickened rim of the antennal socket (fig. 38 D, AR) is 
braced by a short arm against the anterior margin of the heavy cir- 
cumocular ridge {OR). A crescentic area of the head v^^all just above 
and mesad to the antennal socket is depressed externally, and the 
inflection tilts the place of the antennal socket somewhat dorsally, 
giving the antenna a more upward play than it otherwise would have. 

The second basal segment of the antenna, the pedicel (fig. 38 A, 
B, Pdc), is movable in a horizontal plane on the end of the scape by 
means of muscles arising within the scape. The other segments of the 
antenna are flexible but have no muscles. 

The muscles of the antenna comprise muscles inserted on the base 
of the scape that move the antenna as a whole, and the muscles of the 
pedicel that move the pedicel and flagellum. They are as follows : 

4. — Levators of the antenna (fig. 38 C, D). — Two muscles arising 
on tentorium, one (D, 4a) on dorsal arm, the other {4h) on anterior 
arm ; both inserted by a short tendon on a lobe of dorsal side of base 
of scape (C, D). 

5. — Depressors of the antenna (fig. 38C, D). — Two muscles aris- 
ing on dorsal arm of tentorium (D, ^a) and on anterior arm {^b) ; 
both inserted on a long slender tendon arising near ventral margin of 
scape (A, sAp) in articular membrane of antenna. 

6. — Extensor of the flagellum (fig. 38 C). — Arises dorsally and 
medially in base of scape ; inserted medially on base of pedicel. 

7. — Flexor of the flagellum (fig. 38 C). — Arises dorsally and later- 
ally in base of scape ; inserted laterally on base of pedicel. 

THE MANDIBLES 

The mandible of the grasshopper is a strongly chitinous jaw — a 
short, hollow appendage with triangular base, thinning down to the 
cutting margin. The anterior and the posterior angles of the lateral 
base line carry the articular points with the head, and the apodeme 
of the adductor muscles arise at the median angle. 

The distal edge of each mandible presents an incisor and a molar 
area. The first (fig. 39 D, 0) forms the compressed and toothed 
apical part of the jaw, the second (/>) forms a broad grinding surface 
on the anterior median face closer to the base of the mandible. The in- 
cisor and yiolar areas are not exactly alike on the two jaws, each being 



( 



NO. 3 



I XSKCT ]T RAD SNULHiKASS 



best developed on the right. The molar area of the right mandible 
consists of strong, heavy ridges forming a projecting surface ; the 
ridges of the left jaw are low and their area does not project. The 
two molar surfaces, therefore, fit one upon the other without interfer- 
ence when the jaws are closed. The incisor lobes of the mandibles 
close upon the ventral end of the hypopharynx, the molar surfaces 
over its base, and the anterior contour of the hypopharynx is modeled 



AR 




Fig. 39. — Internal structure of the head of Dissosfcirn caroJ'uia, and the 
mandible and its muscles. 

A, inner surface of right half of epicranium. B, tentorium and lower margin 
of epicranium, ventral view. C, iimer view of right half of head, with right 
mandible and its muscles in place. D, right mandible, postero-mesal view. 

a, posterior articulation of mandible ; SAp, abductor apodeme of mandible ; 
gAp, adductor apodeme of mandible; AR, antennal ridge; AT, anterior tentorial 
arm ; at, anterior tentorial pit ; c, anterior articulation of mandible ; Clp, clypeus ; 
cv, cervical sclerite; DT, dorsal tentorial arm; E, compound eye; ER, epistomal 
ridge ; es, epistomal suture ; Fr, f rons ; g, condyle of articulation of cervical 
sclerite ; /;, subocular ridge ; /, subantennal ridge ; Lm, labrum ; Md, mandible ; 
O, ocellus ; 0, incisor lobe of mandible ; p, molar area of mandible ; Poc, post- 
occiput ; PoR, postoccipital ridge; PT, posterior tentorial arm; pt, posterior 
tentorial pit; SgR, subgenal ridge; Smt, submentum ; Int, body of tentorium. 

according to the irregularities of the mandibular surfaces. The pos- 
terior slope of the mandibular hinge lines cause the points of the 
jaws to turn inward, upward, and posteriorly during adduction. At 
the base of each molar area of the mandibles a flat brush of hairs (fig. 
39 C, D) projects inward, and the two brushes come together anterior 
to the mouth opening when the mandibles are closed, serving thus 
evidently to prevent the escape of masticated food material from be- 
tween the jaws. The anterior surfaces of the mandibles are overlapped 
by the epipharyngeal surface of the clypeus and labrum, and the 



I02 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

asymmetry of the mandibular surfaces and contours is reflected in 
that of the epipharyngeal surface (fig. 42 A). 

The mandibles of Dissosfcira are moved, so far as the writer could 
discover, only by tergal abductor and adductor muscles, which, as al- 
ready explained, are the primitive tergal promotors and remotors 
transformed in function by the change from a monocondylic to a 
dicondylic articulation in the mandible (fig. 29 A, B, C). Small 
ventral adductors of the mandibles arising on the hypopharynx and 
on the tentorium persist in some of the Tettigoniidae ( figs. 20 D, 
KLh, 2gC,KL}i, KLt), but these muscles appear to be lost in the 
Acrididae, as they are in all higher pterygote insects. The fibers of the 
functional abductors and adductors arise on the walls of the cranium 
and are inserted on flat apodemal plates of the jaws. The abductor 
apodeme is a small plate (fig. 39 D, 8Ap) arising from the articular 
membrane close to the outer margin of the mandibular base and near 
the posterior articulation (a). The adductor apodeme (pAp) con- 
sists of two large thin plates borne upon a common stalk, which 
arises from the articular membrane at the inner angle of the mandib- 
ular base, and lies in the lateral angle between the anterior and pos- 
terior arms of the tentorium (C). One plate extends dorsally in a 
longitudinal plane, the other, which is smaller, lies in a transverse 
plane. Each mandibular apodeme is a chitinous invagination from the 
articular membrane close to the base of the jaw. The muscles of the 
mandible correspond with the apodemes. They are as follows : 

8. — Abductor of the mandible. — A small fan of fibers, arising on 
ventral part of postgena and on extreme posterior part of ventral half 
of gena ; inserted on abductor apodeme of the mandible. 

p. — Adductors of the mandible (fig. 39 C). — Two sets of fibers 
corresponding with the two divisions of the adductor apodeme. The 
fibers of one set (pa) arise on dorsal wall of cranium, from a point 
between compound eyes to occiput, with one bundle attached on post- 
occiput (Poc) ; inserted on both sides and on posterior margin of the 
median apodemal plate. Those of the other set (pb), inserted on the 
transverse plate of the apodeme, arise on lateral walls of cranium 
from subocular ridge (h) to postgena, and some of the posterior 
fibers encroach upon outer end of posterior tentorial arm. 

THE MAXILLAE 

The maxilla of the grasshopper (fig. 40 A) is so similar to that of 
the roach (fig. 25 A), already described, that its major features will 
need no special description. It consists of a triangular cardo (fig. 
40 A, Cd). a quadrate stipes (St), with a well-developed ])alpifer 






NO. 



INSECT HEAD SNODGRASS 



103 




Fig. 40.— Maxilla and labium of Dissosteira Carolina. 

A right maxilla, posterior surface. B, left maxilla, anterior view, exposing 
muscles of cardo and stipes. C, posterior region of cranium, with cervical 
sclerites and maxilla, left side. D, labium and its muscles, posterior view. L,- 
stipes and palpifer with bases of palpus, galea and lacmia, lacmial muscles re- 
moved, anterior view. . , /■ ^ r „^,i^. 

a, posterior articulation of mandible; loAp, apodeme of promotor of _ cardo 
Cd cardo ; cv, cervical sclerite ; e, articulation of maxilla with cranium ; t, 
articulation of labium with cranium; Ga, galea; Gl, glossa; Lc, lacmia; Mt 
mentum; Mx, maxilla; Oc, occiput; ocs, occipital suture; P^, postgena ; /^//, 
palpifer; Pig, palpiger ; Pip, palpus; Por, postocciput; pos, postoccipital suture; 
^^ posterior tentorial pit; q, suture and internal ridge near inner margin ot 
stipes; r, internal ridge of cardo; s, apophysis of cardo for muscle inseition, 
SID, salivary duct; Suit, submentum ; St, stipes; t, suture and internal ridge 
separating p'alpifer from stipes ; Tut, body of tentorium : u, inner ridge at base 
of posterior wall of galea ; v, keel of salivary cup. 



104 SMITHSONIAN JtllSCIiLLANEOUS COLLECTIONS VOL. 8l 

{Plf), and two terminal lobes, lacinia (Lc) and galea (Ga), and a 
five-segmented palpus (Pip). 

The cardo presents an irregular topography on its external surface, 
and is marked into several areas by the lines of a strong branching 
ridge on its internal surface (fig. 4oB,r). Crampton (1916) calls 
the part proximal and posterior to the ridge the juxtacardo and the 
rest of the sclerite the vcracardo, but the inference that these areas 
are " divisions " of the cardo is scarcely warranted, since the ridge is 
clearly a mere strengthening device. The articular point {c^ of the 
cardo with the cranial margin is a knob on the posterior angle of its 
base, anterior to which is a long arm to which is attached the apodeme 
( loAp) of the promotor muscle (C, 10) . A pit in the distal part of the 
external surface of the cardo (A, s) marks the site of an internal 
process on which one of the adductor muscles is inserted (B, iia). 
The distal margin of the cardo is articulated by a long, flexible hinge 
line with the base of the stipes, but there are no muscles extending 
between the cardo and stipes. 

The quadrate stipes (fig. 40 A, St) has a strong plate-like ridge 
on its internal surface near the inner margin (g), on which is in- 
serted one of the adductor muscles (E, 12). Crampton distinguishes 
the body of the stipes as the vcrastipcs, and the flange mesad of the 
muscle-bearing ridge as the jnxtastipcs. The region of the palpifer 
(A, Plf) is well separated from that of the stipes by an internal ridge 
(E, /), but the muscles of the palpus ( //, 18), as well as the muscle 
of the galea {16). have their origin in the stipes, suggesting that the 
palpifer is a subdivision of the stipes, and not a basal segment of the 
palpus. 

The lacinia (fig. 40 A, B, Lc) is borne by the distal end of the stipes, 
and is capable of flexion anteriorly and posteriorly on an oblique axis 
with the latter. Distally it tapers and ends in two claws turned in- 
ward. The lacinia is flexed by a pair of strong muscles arising within 
the stipes (B, i^^a, 13b), and by a slender muscle (/./) having its 
origin on the wall of the craniuuL 

The galea (fig. 40 A, Ga) is carried by a distal subdivision of the 
palpifer, which Crampton (1916) calls the basigalea. In form, the 
galea (A, B, C, Ga) is an oval, flattened lobe ; its walls are but weakly 
chitinized. Its inner margin lies against the lacinia, and its outer 
surface is modeled to fit the outer part of the posterior surface of 
the mandible, against which it can be tightly closed. The base of the 
galea is marked on the posterior wall by an internal ridge (E, m), upon 
which is inserted its single flexor muscle {j6). 



f 



so. 3 INSECT llRAl) SNODGKASS I05 

The maxillary palpus consists of five segments (lig. 40 A, B, C. 
Pip). The basal segment is provided with levator and depressor mus- 
cles (B, E, I/, 18) arising within the stipes; each of the other seg- 
ments has a single muscle arising in the first or second segment proxi- 
mal to it. 

The muscles of a maxilla are as follows : 

10. — Promotor of the cardo (fig. 40 C). — A small fan of fibers 
arising on lower posterior part of postgena, external and anterior to 
the mandibular abductor ; inserted on slender apodeme of basal arm 
of cardo. 

//. — Adductors of the cardo (fig. 40 B). — Two muscles arising on 
posterior end of anterior arm of tentorium, extending ventrally, pos- 
teriorly, and outward; one {iia) inserted on process {s) of inner 
face of cardo, the other (iih) mesad to distal end of ridge (r) of 
cardo. 

12. — Proximal adductor of the stipes (fig. 40 E). — Arising on ex- 
treme posterior end of anterior arm of tentorium; inserted on ridge 
of inner margin of stipes. 

7j. — Distal adductors of the stipes (fig. 40 E). — Two muscles 
arising on tentorium, the first (13a) a slender muscle arising, along 
with iia, lib, and 12, on posterior end of anterior arm of tentorium, 
the second (isb) a large, thick, digastric muscle arising laterally on 
concave ventral surface of body of tentorium ; both muscles inserted 
on a slender apodeme attached to inner distal angle of stipes. 

Muscles II, 12, and 13 correspond with the adductors of the cardo 
and stipes that in Apterygota arise on the hypopharyngeal apodemes 
(fig. 30 B, KLcd, KLst), representing the sternal adductors, or ster- 
nal promotor and remotor, of a primitive appendage (fig. 35 B, A', L). 

14. — Cranial flexor of the lacinia (fig. 40 B). — Arises on gena just 
before upper end of promotor of cardo (C, 10) ; inserted on inner 
angle of base of lacinia. This muscle is the homologue of the cranial 
flexor of the maxillary lacinia in Apterygota (fig. 30 B, /?cc), and of 
the corresponding flexor of the mandibular lacinia in Myriapoda (fig. 
26 A, B, Cflcc). 

75. — Stipital flexor of the lacinia (fig. 40 B). — A large two- 
branched muscle arising in base of stipes, one branch {13a) medially, 
the other (ifib) in outer basal angle ; both inserted on anterior margin 
of base of lacinia. These muscles flex the lacinia forward. Berlese 
( 1909) describes the posterior branch of this muscle in Acridium as 
attached to the posterior wall of the lacinia, and as being an antagonist 
to the anterior branch, but in no insect has the writer observed an 
antagonist to the lacinial flexor. 



I06 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

i6. — Flexor of the galea (fig. 40 B, E). — A large muscle arising 
mesally in base of stipes, external to lacinial muscles and depressor of 
palpus; inserted posteriorly on ridge (E, u) at base of galea. This 
muscle probably flexes the galea forward and inward, the point of flex- 
ion being at the base of the subgalea. 

//. — Levator of the maxillary palpus (fig. 40 B, E). — Origin in 
median basal part of stipes ; insertion on dorsal margin of basal seg- 
ment of palpus. 

18. — Depressor of the maxillary palpus (fig. 40 B, E). — Origin on 
inner edge of stipes; crosses anterior to muscle of galea {16) to in- 
sertion on ventral margin of basal segment of palpus. 

If the basal segment of the palpus (fig. 35 A) corresponds with 
the trochanter of the leg (fig. 34 B, Tr), then muscles ij and iS 
represent the levator and depressor of the telopodite (fig. 34 A, 0, 
Q) arising in the coxal region of the leg base (LB). 

ip, 20, 21, 22. — Muscles of the maxillary palpus (fig. 40 B). — A 
single muscle for each segment, the first (ip) a levator of second seg- 
ment, the second {20) a productor of third segment, the third (21) 
a depressor (adductor) of fourth segment, the fourth {22) a reductor 
of terminal segment. 

The joint between the third and fourth segments of the palpus 
apparently represents the femero-tibial flexure of a leg (figs. 34, 35 
A, ft), the two small basal segments of the palpus being trochanters. 

THE LABIUM 

The labium of the grasshopper (fig. 40 D) is simple in construction, 
and typical of the labium of biting insects, except in the reduction of 
the glossae. It consists of a largei submentum (Smt) with the elongate 
basal angles loosely attached to the posterior margin of the cranium 
behind the roots of the posterior tentorial arms (C, /). The mentum 
(D, Mt) is broad, with imperfectly differentiated palpus-bearing 
lobes, or palpigers (Pig), at the sides of its base. On its ventral 
margin the mentum bears a pair of large flat lobes, the paraglossae 
(Pgl), with a pair of rudimentary glossae (Gl) between them. Each 
palpus is three-jointed. 

At the base of the anterior surface of the mentum, where the wall 
of the mentum is reflected into that of the hypopharynx (fig. 41), 
there is a small, median, oval, cup-shaped depression into which opens 
the duct from the salivary glands (SID). A small prominence on the 
base of the hypopharynx fits into the salivary cup and apparently 
closes the latter when the labium is pressed against the hypopharynx. 



NO. 3 INSECT HEAD SNODGRASS loy 

The walls of the salivary cup are chitinous, and its posterior inner 
surface bears a strong chitinous keel (figs. 40 D, 41 z') projecting 
into the interior of the labium in the base of the mentum. Two pairs 
of muscles (figs. 40 D, 26, 2y) are attached upon the keel and the 
walls of the salivary cup. 

The musculature of the labium is in general similar to that of the 
maxillae. It includes the following muscles : 

i'J. — Proximal retractors of the mentum (fig. 40 D). — A pair of 
muscles arising on ventral surfaces of posterior tentorial arms ; in- 
serted on lateral basal angles of mentum. 

24. — Distal retractors of the menttim (fig. 40 D).^ — A pair of mus- 
cles arising on posterior surfaces of posterior tentorial arms ; extend- 
ing through submentum and mentum to be inserted on anterior wall 
of labium at inner basal angles of the glossae. The distal parts of 
these muscles are not seen in figure 40 D, being covered posteriorly 
by muscles 2^ and 2j. The labial muscles 2^ and 24 evidently cor- 
respond with the tentorial adductors of the maxillae (E. 12, jj). 

2 J. — Flexors of the paraglossae (fig. 40 D). — A pair of large mus- 
cles arising in lateral basal angles of mentum ; inserted on bases of 
paraglossae, to posterior walls, near inner ends. Each of these muscles 
corresponds with the flexor of the galea in the maxilla (E, 16). 

The small labial glossae of Dissosteira have no muscles. 

26, 2/. — Muscles of the salivary cup (fig. 40 D). — Two pairs of 
muscles: one pair (26) arising on basal angles of mentum, converg- 
ing to insertions on keel of salivary cup ; the other pair (<?/) arising 
on posterior wall of mentum near bases of palpi, converging proxi- 
mally to insertions on sides of salivary cup. These muscles apparently 
have no homologues in the maxillae ; perhaps they are special labial 
muscles having something to do with the regulation of the flow of 
saliva from the salivary duct. 

28.— Levator of the tahial palpus (fig. 40 D). — Origin in lateral 
basal angle of mentum ; insertion on dorsal rim of base of palpus. 

2Q. — Depressor of the labial palpus (fig. 40 D). — Origin in distal 
median angle of mentum ; insertion on ventral rim of base of palpus. 

30, 5/. — Muscles in the labial palpus (fig. 40 D). — The first (30) 
a levator of second segment; second (5/) a depressor (adductor) of 
third segment. 

THE PREORAL CAVITY AND THE HYPOPIIARYNX 

The intergnathal space, or preoral cavity, of the grasshopper (fig. 
41, PrC) is of large size, but it is mostly filled by the thick, tongue- 
like hypopharynx suspended from its roof (Hphy). Its anterior wall 



io8 



SMITHSONIAN M JSCi;i.LANEOUS COl.r.KCTli )\S 



VOi.. 81 



is the posterior surface of the clypeiis and labruni {Lip, Lin ). which 
in the grasshopper is not produced into a specially developed lohe, 
or epipharynx. The lateral walls are the inner faces of the mandibles 
and maxillae ; the posterior wall is the anterior surface of the labium 
{Lb). The dorsal wall of the cavity represents the true sternal region 
of the head, sloping downward and posteriorly from the mouth open- 
ing to the base of the labium. It is mostly produced into the large, 




Hphy 



Fig. 41. — Stomodeum, and its dilator muscles in right half of head of 
Dissostcira Carolina. 

Clp, clypeus ; Cr, crop ; cs. epistonial suture, Fr, f rons ; Hphy, hypopharynx, 
Lb, labium; Lm, labrum ; Mth, mouth; Fhy, pharynx; Pre, preoral cavity; SID, 
salivary duct ; Tnt, tentorium ; v, salivary cup. 



median hypopharynx {Hphy), leaving otherwise only a narrow mem- 
branous area on each side between the base of the hypopharynx and 
the bases of the mandible and maxilla. 

The anterior or epipharyngeal wall of the preoral cavity presents 
a number of features of special interest (fig. 42 A). The lateral 
parts of the labral region of this wall are concave and fit closely over 
the smooth, rounded, anterior surfaces of the mandibles. The bands 
of hairs directed inward on the labral surface guard the exits from 



NO. 3 INSECT HKAL) SxXOlXIKASS IO9 

l)et\veen the mandibles, and the asymmetrical forms of the hair- 
covered areas here correspond with the different shapes of the two 
mandibles. Minute sense organs are scattered over this labral surface, 
especially on the bare lateral regions. A special group of similar but 
somewhat larger sense organs lies at each side of the notch in the 
ventral border of the labrum. The median area of the basal half of 
the labral surface forms a low elevation, the sides of which are thickly 
covered with long spine-like hairs curved inward and upward. This 
elevation projects between the inner edges of the closed mandibles, 
and its irregular contours fit with the lines of the opposing jaws. Its 
median surface is depressed and embraces the region of the internal 
Y-shaped ridge ( /// ) . The elevation is continued upward on the clyp- 
cal region, above the spreading arms of the Y-shaped ridge, and be- 
tween the inner recurved ends of the tormae (Tor), and then into 
the mouth (Mth) and upon the anterior wall of the buccal cavity. A 
sinuous groove begins upon the elevation ventrally between the tormae, 
which extends dorsally and enlarges into a deep, median channel con- 
tinued into the anterior wall of the mouth and pharynx. At the sides 
of the lower end of the channel, between the slender arms of the 
tormae, are four asymmetrically placed, oval groups of small peg-like 
sense organs with large circular bases, partly covered from the sides 
by fringes of long recumbent hairs. 

The hypopharynx is a large median lobe suspended, as already noted, 
from the ventral wall of the head between the mouth and the base 
of the labium (fig. 41, HpJiy). Its posterior end is closely covered 
by the paraglossal lobes, and its sides are concealed by the mandibles 
and maxillae. In form, as seen from below (fig. 42 C), the hypo- 
])harynx is somewhat ovate, with the smaller end anterior, but its pos- 
terior end is set off as a narrowed lobe by lateral constrictions. The 
lateral surfaces of the anterior division fit into the posterior concavi- 
ties of the mandibles, those of the posterior lobe are embraced by the 
concave inner faces of the laciniae. The posterior, basal extremity of 
the hypopharynx projects as a small median process into the salivary 
cup on the base of the labium (tig. 41 ). The lateral line of the hypo- 
pharyngeal base is marked bv a slender, sinuous, chitinous bar on each 
side (zv). The arrangement of the hairs clothing the hypopharynx is 
sufficiently shown in the figures (figs. 41. 42 C). On its sides and 
at the posterior end near the salivary cup are a few small sense organs 
similar to those of the labrum. 

Dorsal to the anterior end of the hypopharynx is an area that leads 
directly upward into the floor of the mouth. It possibly represents the 
sternal region of the protocephalic segments of the head. On its 



k 



no 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 



median surface (fig. 42 B, C) is a ridge, bordered by long hairs di- 
rected inward and upward, that continues dorsally from the narrowed 
end of the hypopharynx, and which is excavated by a median channel 
where it enters the mouth. At each side of this channel is an oval 
group of sense organs. Flanking the ridge are two chitinous bars 
(HS), the ventral ends of which articulate with the anterior extrem- 
ities of the lateral basal rods of the hypopharynx (w). Dorsally 
each bar forks into two arms, of which one (x) goes posteriorly to 




Fig. 42. — The epipharyngeal surface, and the hypopharynx of Dissosteira 
Carolina. 

A, epipharyngeal surface of clypeus and labrum, and ventral extremity of 
pharynx. B, lateral view of mouth opening, and of suspensorial apparatus of 
hypopharynx. C, antero-ventral view of hypopharynx and its suspensory rods. 

9Ap, apodeme of adductor muscle of mandible ; Clp, clypeus ; Hphy, hypo- 
pharynx ; HS, suspensorial bar of hypopharynx ; Lm, labrum ; in, Y-shaped ridge 
in epipharyngeal wall of labrum ; Mth, mouth ; Phy, pharynx ; Pnt, small lobe 
behind angle of mouth, possibly rudiment of tritocerebral appendage; Tor, 
torma ; iv, lateral basal bar of hypopharynx ; x, mandibular branch of sus- 
pensorial bar (HS) of hypopharynx; y, oral branch of same. 

the base of the adductor apodeme of the mandible (pAp), and the 
other (y) goes anteriorly, laterally, and dorsally into the angle of the 
mouth, where it forms a support for the insertion of the retractor 
muscle of the mouth angle (A, B, ^8). 

The two lateral bars (fig. 42 B, HS) in the space between the hypo- 
pharynx and the mouth, with their posterior dorsal arms (x) braced 
against the bases of the mandibular apodemes. and their ventral 
ends articulated with the basal rods (zv) of the hypopharynx, consti- 
tute a movable suspensorial apparatus of the hypopharynx. It is 
evident that a contraction of the mouth angle muscles (38) inserted 



NO. 3 INSECT HEAD SNODGRASS III 

on the anterior dorsal arms (y) of the bars must effect a movement 
of the hypopharynx, and that the latter would be lifted and swung 
forward beneath the mouth opening. The pull of the mouth muscles, 
however, also retracts the mouth angles, and there is probably thus 
accomplished a closing of the mouth upon the food mass accumulated 
in the preoral space above the anterior end of the hypopharynx. In 
the grasshopper, the mouth is closed also by the opening of the jaws, 
but, so far as can be observed in a dead specimen, the closing of the 
mouth in this case results mechanically from the transverse stretch- 
ing of the oral aperture between the separating bases of the adductor 
apodemes of the mandibles. 

Posteriorly the hypopharynx is fixed to the base of the labium, where 
its wall is reflected into that of the latter (fig. 41). The hypopharynx, 
therefore, can swing forward only in unison with the labium, but other- 
wise it is free to move to the extent permitted by the membranous 
areas laterad of its base. The only muscles properly belonging to the 
hypopharynx are the following: 

32. — Retractors of the hypopharynx (figs. 40D, 41) — A pair of 
muscles arising posteriorly on extreme lateral ends of anterior arms 
of tentorium (fig. 40 D) ; inserted on posterior parts of basal rods of 
hypopharynx (fig. 41). 

The contraction of these muscles probably retracts the hypopharynx, 
and pulls the hypopharynx and labium posteriorly. The mouth aper- 
ture is opened by the contraction of the dilator muscles inserted on 
its anterior and posterior walls (figs. 41, 44, JJ, 34, 41). 

The rods {HS) of the suspensory apparatus of the hypopharynx 
in the grasshopper are evidently remnants of the much larger sus- 
pensory plates of the hypopharynx in Apterygota and Myriapoda 
(fig. 21 A, B, C, E, HS). In Microcentrum, as already shown (fig. 
20 D), a small hypopharyngeal adductor muscle of the mandible is 
attached to the end of each rod. In the roach (Periplancta) the chi- 
tinous parts of the hypopharyngeal suspensorium are more strongly 
developed than in the grasshopper, and their action can be more clearly 
demonstrated. In the bees, though the hypopharynx itself may be 
lacking, the oral arms of the suspensory bars are prolonged as slender 
rods into the lateral walls of the pharynx, and their basal ends are 
bridged by a wide plate on the pharyngeal floor. 

In Dissosteira there is at each side of the mouth, in the angle between 
the dorsal arms of the suspensorial bar of the hypopharynx, a very 
small but distinct membranous lobe of a definite form (fig. 42 B, Pnt), 
but having no apparent function, and bearing neither hairs nor sense 



Ik 



112 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 



organs. The position of these lobes between the mouth and the ad- 
ductor apodemes of the mandibles strongly suggests that they are 
rudiments of the postantennal appendages of the tritocerebral seg- 
ment, which have otherwise not been observed in the adult of any 
pterygote insect. 

THE STOM ODEUM 

At the upper end of the preoral cavity (fig. 41, PrC), anterior to 
the base of the hypopharynx, and immediately behind the base of the 
clypeus is the true mouth (Mth), or external opening of the stomo- 
deum. The mouth of Dissostcira is a transverse aperture having 
acute lateral angles, I)Ut without definite " lips," for the epipharyngeal 




Fig. 43. — Pharynx, crop, anterior gastric caeca, and associated organs of 
Dissosteirn Carolina. 

Ao, aorta; CA, corpus allatum (?) ; Cr, crop; FrGng, frontal ganglion; GC, 
gastric caecum ; LNv, lateral stomodeal nerve ; OeGiiy, posterior median or 
oesophageal ganglion ; Phy, pharynx ; PLGng, posterior lateral stomodeal gan- 
glion ; Pvcnt, proventriculus. 

and the supra-hypopharyngeal walls are directly continued into the 
anterior and posterior walls of the buccal cavity and pharynx. 

The stomodeum of the grasshopper extends from the mouth upward 
in the anterior part of the head (fig. 41). then turns posteriorly above 
the tentorium, and continues rearward through the head and thorax 
into the base of the abdomen (fig. 43). By differences in its diameter 
and in the character of its walls, the stomodeum is differentiated into 
several parts, but only three parts are well defined in the grasshopper ; 
these are the pharynx, the crop, and the proventriculus. 

The pharynx, or first division of the stomodeum. is a narrow, mus- 
cular-walled tube bent downward to the mouth between the anterior 
arms of the tentorium (figs. 41, 43, 44, PJiy). The region of the 
mouth, including the upper end of the preoral cavity (fig. 41, PrC) 
and the part of the stomodeum just within the oral aperture, may be 
distinguished as the buccal covitv because the muscles inserted on it 



NO. 3 INSECT HEAD SNODGRASS II3 

(figs. 41, 44, J5, S4' 3^^ 41) function in connection with the mouth. 
The dorsal dilators {33, 34) arise upon the clypeus (fig. 41, Clp). 

The true pharyngeal region of the stomodeum of the grasshopper 
is differentiated into an anterior pharynx and a posterior pharynx, 
the two parts being thus named by Eidmann (1925) in the roach. 
The principal differences between the two parts of the pharynx, how- 
ever, are in the conformations of the cuticular lining, though the 
posterior end of the anterior pharynx is marked externally by a slight 
bulging of the lateral walls. The circumoesophageal connectives (fig. 
44, CoeCon) lie approximately between the two pharyngeal sections. 

The crop (fig. 43, Cr) is a large, rather stiff-walled sack, represent- 
ing probably both oesophagus and crop in insects with a long oesoph- 
ageal tube, though the posterior section of the pharynx in the grass- 
hopper appears to be the oesophageal region in the caterpillar (fig. 
55). The anterior end of the crop in Dissosteira lies in the back of 
the head where it rests upon the bridge of the tentorium (fig. 41) : 
the ventral surface of the thoracic part of the organ is supported by 
the spreading apophyses of the thoracic sterna. The anterior third of 
the crop (fig. 43) is somewhat set off from the rest by a slight nar- 
rowing of the walls ; the posterior part tapers between the large 
anterior caecal pouches of the ventriculus, and ends in the proventric- 
ulus (Pvent). The proventriculus is a small, cup-shaped enlarge- 
ment of the posterior end of the stomodeum, mostly concealed between 
the bases of the ventricular pouches (GC). 

The frontal ganglion of the stomodeal (stomatogastric) nervous 
system (fig. 43, FrGng) rests against the anterior wall of the pharynx, 
and the posterior median oesophageal ganglion (OeGng) lies over 
the posterior end between the spreading bases of the last pair of dorsal 
dilator muscles of the pharynx (j/). From this second median gan- 
glion a long lateral nerve {LNv) goes posteriorly on each side of the 
crop, ending on the rear part of the latter in a posterior lateral gan- 
glion (PLGng). A pair of short anterior lateral nerves from the 
oesophageal ganglion go laterally to a pair of globular bodies, possibly 
the corpora allata (CA) , lying at the sides of the posterior pharynx. 
The anterior dilated end of the aorta (Ao) rests upon the oesophageal 
ganglion, and its open, trough-like lower lip is extended forward be- 
neath the brain. 

The Inner Wall of the Stomodeum. — The surface of the intima, or 
cuticular lining, of the pharynx, crop, and proventriculus is diversified 
by various folds and ridges, most of which are clothed with hairs or 
are armed with small chitinous teeth. 



114 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

The channels on the walls of the preoral cavity that lead into the 
mouth are continued upon the inner w^alls of the anterior pharynx. 
The median epipharyngeal groove proceeds upward on the anterior 
pharyngeal wall between two converging ridges, but it soon ends 
in a thick median fold which follows the midline of the roof of the 
posterior pharynx to the end of the latter. Likewise, the median 
channel leading upward from the base of the hypopharynx is con- 
tinued on the rear wall of the anterior pharynx, between two con- 
verging ridges, and ends in a median ventral fold on the floor of the 
posterior pharynx. From the lateral angles of the mouth, wide chan- 
nels go dorsally in the side walls of the anterior pharynx, but these 
again end each in a lateral fold of the posterior pharynx. Thus the 
relative positions of the principal ridges and grooves in the walls of 
the two parts of the pharynx are reversed. In the posterior pharynx 
there is a slenderer intermediate fold between each two of the major 
dorsal, lateral, and ventral folds. These eight folds of the posterior 
pharynx end at the entrance of the crop, giving the aperture a stellate 
appearance when seen from the lumen of the crop. All the pharyngeal 
folds, except the midventral fold of the posterior pharynx, are clothed 
with hairs directed backward. 

In the crop, a wide dorsal channel proceeds from the pharyngeal 
opening posteriorly on the anterior third of the upper wall between 
converging folds of the intima. A narrower ventral channel follows 
the midline of the floor between a pair of folds that diverge posteriorly 
and are lost beyond the middle of the organ. The lateral walls of 
the anterior half of the crop are closely corrugated by obliquely trans- 
verse ridges, which bear rows of small, slightly curved, sharp-pointed, 
chitinous teeth projecting backward. The anterior three or four 
transverse ridges on each side are particularly conspicuous by reason 
of their greater width, and because they are thickly beset with similar 
but slightly larger teeth than those of the other ridges. In the posterior, 
narrowed part of the crop the transverse ridges are replaced by fine, 
parallel, lengthwise folds, following the lines of the longitudinal 
muscle fibers. Numerous teeth are present here also, but they are 
smaller and blunter than those of the anterior region, and are mostly 
arranged in small groups, usually two or three together, on elevations 
of the intima along the folds. The interior characters of the crop are 
better developed and the teeth are more numerous in the larger organ 
of the female grasshopper than in that of the male. They can be 
studied best on pieces of the intima stripped from the tough muscular 
sheath of the crop. 



NO. 3 INSECT HEAI3 SNODGRASS II5 

The walls of the short proventriculus are produced into six flat, 
triangular elevations having their bases contingent anteriorly, and their 
apices directed backward, where they all end on the rim of the wide, 
round orifice into the ventriculus. The proventricular ridges are not 
mere folds of the intima, for each is formed by a thick mass of the 
underlying epithelial cells. The surface of the intima in the pro- 
ventriculus is smooth, except for a few very small teeth on the edges 
of the triangular ridges, and areas of minute granulations on the distal 
halves of the latter. The posterior margin of the proventricular wall 
is reflected outward upon itself to form a short circular fold project- 
ing into the anterior end of the ventriculus, reaching just past the 
openings of gastric caeca. The intima covers the outer surface of the 
fold, but terminates at the base of this surface. The line of the latter, 
therefore, marks the end of the stomodeal or anterior ectodermal 
section of the alimentary canal. 

The Muscular Sheath of the Stomodeum. — The stomodeal walls 
are everywhere covered with flat bands of muscles, which in general 
take a transverse and a longitudinal direction, the transverse bands 
l)eing external and the longitudinal internal; but the distribution of 
the two sets is not such as to form a regular net-pattern on all parts 
of the stomodeum. On the posterior two-thirds of the crop, the ex- 
ternal transverse fibers have the form of continuous rings encircling 
the organ, and the longitudinals run with its length. On the anterior 
third, however, the ring muscles are interrupted laterally and dorsally. 
and their layer is continued only on the ventral surface as a series of 
ventral arcs ; but the fibers of a latero-ventral tract of the posterior 
longitudinal muscles on each side curve upward on the lateral wall of 
the crop where the circular bands are interrupted, and are continuous 
wi'th those from the opposite side over the dorsal surface as an external 
layer of obliquely transverse fibers reaching to the base of the pharynx. 
On the pharyngeal tube the muscles again take the pattern of regularly 
arranged external circular and internal longitudinal fibers. The cir- 
cular fibers of the pharynx may belong to the interrupted set of circular 
fibers of the crop, but the longitudinal fibers are continued irregularly 
into the walls of the crop on the inner surface of the anterior circular 
fibers of the latter, and they do not, therefore, belong to the same 
layer as the posterior longitudinal crop muscles. A close study of 
the stomodeal musculature of the grasshopper would show some com- 
plexity of detail in the arrangement and relationship of the muscle 
fibers, but nothing approaching the intricacy of the fiber connections 
in the muscular layers on the pharynx and crop of the caterpillar, to 
be described later. 



ii6 



SMITHSONIAN MISCF.LLANEOrS COLLECTIONS VOL. 8l 



The Dilator Muscles of tJic Stomodeuni.—Th\rttQ.n paired sets of 
muscle fibers and one median unpaired muscle arising on the skeletal 
parts of the head or thorax are inserted on the stomodeal walls in 
Dissosteira (figs. 41, 43, 44). These muscles may be classed as dor- 
sal, lateral, and ventral according to their insertions, though because 
of the downward flexure of the pharynx, the first " dorsal " and 
" ventral " muscles are anterior and posterior. The dilator muscles 
of the stomodeum, sometimes called also suspensory muscles, enumer- 
ated from 55 to 46 inclusive, are as follows : 




Fig. 44.— Dilator muscles of the buccal region, pharynx, and crop of 
Dissosteira Carolina. 

CocCon, circumoesophageal connective: Cr, crop; Mth. mouth; Tut. tentorium. 



55. — First anterior dilators of the buccal cavity (figs. 41, 44). — 
A pair of fan-shaped muscles arising on inner wall of clypeus (fig. 
37 B), the fibers spreading to their insertion on anterior wall of buccal 
cavity (fig. 44) mostly distal to oral aperture. 

^4. — Second anterior dilators of the buccal cavity (figs. 41, 44). — 
A pair of fan-shaped muscles similar to j?, arising on clypeus near 
epistomal ridge (fig. 3/ B) ; inserted laterad of jj and mostly proxi- 
mal to oral aperture. 

J5. — First dorsal dilators of the pharynx (figs. 41, 44). — A pair of 
slender muscles arising on frontal area of head wall, each attached 
between labral retractors of same side (fig. 38 D) ; inserted on anterior 
wall of pharynx. 



t 



NO. 3 INSECT HEAD SNODGKASS II7 

36. — Second dorsal dilators of the pharynx (figs. 41. 44). — Each 
arises by a slender stalk on sulmntennal ridge of frons (fig. 41) ; in- 
serted by spreading base on upper end of anterior pharynx. 

37. — Third dorsal dilators of the pharynx (figs. 41, 43. 44). — Each 
arises by slender stalk on vertex near inner rim of compound eye 
just anterior to first dorsal fibers of mandibular adductor ; inserted 
by widely spreading base on dorsal wall of posterior pharynx. 

38. — Retractors of the mouth angles (figs. 41, 44). — These, the 
largest muscles of the stomodeum, and the first of the lateral series, 
arise on the subantennal ridges of the frons (fig. 38 D), and extend 
downward and posteriorly to their insertions on the oral arms of the 
hypopharyngeal suspensorial rods (figs. 42 A, B, 44) in the lateral 
angles of the mouth. 

jp. — First lateral dilators of the pharynx (fig. 44). — A pair of 
slender muscles arising laterally on frontal region ; inserted on sides 
of anterior pharynx. 

40.- — Second lateral dilators of the pharynx (figs. 41, 44). — A slen- 
der muscle on each side, arising on posterior face of distal end of dor- 
sal arm of tentorium (fig. 41) ; inserted by spreading base on upper 
end of anterior pharynx (fig. 44). 

41. — Ventral dilator of the buccal cavity (figs. 41, 44). — A median, 
unpaired, strap-like muscle arising on ventral face of body of tentor- 
ium ; inserted on median groove of posterior wall of mouth. 

42. — First ventral dilators of the pharynx (figs. 41, 44). — A pair 
of fibers arising on ventral surface of tentorium ; going anteriorly to 
insertions medially on lower end of posterior wall of anterior pharynx. 

43. — Second ventral dilators of the pharynx (figs. 41, 44). — A 
group of diverging fibers on each side, arising on anterior edge of 
tentorium ; inserted latero-ventrally on anterior pharynx. 

44. — Third ventral dilators of the pharynx (figs. 41, 43, 44). — A 
large fan of fibers on each side, arising on dorsal edge of posterior 
arm of tentorium ; the spreading fibers inserted ventro-laterally along 
entire length of posterior pharynx. 

45. — Anterior dilators or protractors of the crop (figs. 41, 43, 44). 
— A large group of fibers arising on each posterior tentorial arm. 
behind origin of 44 ; spreading posteriorly to insertions ventro-later- 
ally along anterior third of crop. These are the last of the stomodeal 
muscles that have their origin in the head. 

46. — Posterior protractors of the crop and gastric caeca (fig. 43). — 
A pair of long, branched muscles, each arising by a slender stalk on 
inner surface of prothoracic tergum, just anterior to base of troch- 
antinal muscle ; branching downward and posteriorly, one branch in- 



Il8 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

serted on lateral wall of crop just above posterior lateral stomodeal 
ganglion {PLGiig), the others on tii)s of the gastric caeca (GC) of 
same side. 

THE MECHANISM FOR MOVING THE HEAD 

The head of the grasshopper is freely attached to the prothorax by 
a membranous neck, but its movements are somewhat limited by the 
overlapping anterior edges of the protergum, and by the pair of 
cervical sclerites on each side (fig. 45 B, icv, 2cv) which link the head 
with the concealed episternal plate of the prothorax (Eps^). 

The cervical sclerites, however, constitute an important part of the 
mechanism for moving the head The two plates of each pair are 
articulated end to end, and ordinarily they are bent downward at an 
angle to each other (fig. 36 A, cv). The first is articulated anteriorly 
to the posterior margin of the postoccipital rim of the head (fig. 45, 
g), the second posteriorly to the anterior edge of the prothoracic 
episternum (EpSi). The neck plates thus constitute a fulcrum on each 
side between the head and the thorax, giving a leverage to the dorsal 
and ventral muscles extending from the postoccipital ridge and ten- 
torium to the prothorax and the first thoracic phragma. Moreover, 
upon each plate are inserted strong levator muscles (fig. 45 B) arising 
on the back of the head and on the prothoracic tergum, and the con- 
traction of these muscles, with the consequent straightening of the 
angle between the two plates of each pair, must cause the protraction 
of the head. From each anterior plate a horizontal muscle extends to 
the prosternal apophysis of the opposite side (fig. 45 A, B, 5^). Be- 
sides the muscles that connect the skeletal parts of the head, neck, 
and prothorax, there are two muscles on each side inserted directly 
upon the neck membrane (A, 5<5, 57). 

It is difficult to give names signifying function to the neck muscles, 
for it is evident that the function will depend on whether the two 
muscles of any pair act in unison, or as antagonists. The neck muscles 
of Dissosteira are as follows, on each side : 

4/. — First protergal muscle of the head (fig. 45 A). — A slender 
muscle arising dorsally on prothoracic tergum ; inserted dorso-later- 
ally on postoccipital ridge of head (PoR). 

48. — Second protergal muscle of the head (fig. 45 A). — A larger 
muscle arising on principal ridge of protergum (e) ; inserted with 4/ 
on postoccipital ridge of head. 

4p. — Longitudinal dorsal muscle of the prothorax (fig. 45 A). — • 
Extends from first thoracic ])hragma ( rPh) to postoccipital ridge 
(PoR) just l^elow 48. 



NO. 3 



INSECT HEAD SNODGRASS 



119 



50> 5^- — Cephalic muscles of the cervical plates (fig. 45 A, B). 

Origin on postoccipital ridge below 4p; both extend ventrally and 
posteriorly, the first (30) inserted on first cervical plate, the second 
(57) on second plate. 

5^. 53-—Protergal muscles of the cervical plates (fig. 45 B).— 
Origin dorso-laterally on prothoracic tergum; both extend ventrally 
and anteriorly, crossing internal to 50 and 51, to be inserted on first 




Fig. 45. — Muscles of the neck of Dissosfeira Carolina, right side, internal 
view. 

A, muscles extending between head and prothorax, omitting 52, 5-3 and 54, 
inserted on cervical sclerites (B). B, head and prothoracic muscles of cervical 
sclerites. 

Bsi, basisternum of prothorax; c, first ridge of protergum; icv, first cervical 
plate ; ^cv, second cervical plate ; d, second ridge of protergum ; e, third ridge 
of protergum; Epsi, episternum of prothorax; EpS2, episternum of mesothorax ; 
g, process of head articulating with first cervical sclerite; H, head; iPIi, first 
thoracic phragma; PoR, postoccipital ridge; FT, base of posterior arm of 
tentorium ; Rd, posterior fold of protergum ; SA, apophysis of prothoracic 
sternum ; Spn, spina ; Ti, tergum of prothorax. 

cervical plate, the first {32b) with a branch {32a) to articular process 
(g) oi postoccipital ridge. 

34. — Prosternal muscle of the first cervical plate (fig. 45 A, B). — A 
diagonal, horizontal muscle arising on apophysis of prothoracic ster- 
num (A, SA), crossing its fellow to insertion on inner edge of first 
cervical plate of opposite side (B). 

33. — Longitudinal ventral muscle of the prothorax (fig. 45 A). — A 
broad, flat muscle from prosternal apophysis (SA) to base of poste- 
rior arm of tentorium (PT). 



'Wl 



120 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOL. 



56. — Dorsal lateral neck nittsclc (tig. 45 A). — A band of slender 
fibers from first phragma ( iPli), inserted on base of neck membrane. 

57. — J^cntral lateral neck muscle (fig. 45 A, B). — A short, flat 
muscle from anterior edge of prothoracic episternum {EpSi), inserted 
on base of neck mem]:)rane. 

VI. SPECIAL MODIFICATIONS IN THE STRUCTURE 
OF THE HEAD 

The important structural variations in the head of biting insects 
afifect principally the f ronto-clypeal area, and the posterior lateral and 
ventral regions. Modifications of the facial plates are often to be 
correlated with variations in the relative size of the buccal and pharyn- 
geal parts of the stomodeum, or with a special development of the 
mouth cavity. Modifications in the posterior ventral parts of the head 
are correlated with a flattening and elongation of the cranial capsule, 
usually resulting from an upward tilting of the head on the neck 
by which the mouth parts become directed forward, and, in certain 
orders, are accompanied by an elongation of the submentum an- 
teriorly, with a dififerentiation of this plate into a posterior gular 
sclerite and a secondary anterior submental sclerite. 



MODIFICATIONS IN THE FRONTO-CLYPEAL REGION 

The prostomial part of the insect head includes the frons, the clyp- 
eus, and the labrum. Whether or not it comprises also the region 
of the compound eyes may be regarded as an open question, and one 
for the embryologists to settle. If the compound eyes belong to the 
first true segment of the head, it is probable that the frontal sutures 
define the posterior limit of the prostomium ; otherwise the sutures 
must be secondary formations within the area of the prostomium. The 
frontal sutures do not always mark the lines of cleavage in the head 
cuticula at the time of a molt. In an odonate nymph, for example 
(fig. 46 I), the facial clefts (t) of the molting cuticula extend from 
the coronal suture outward and downward on each side between the 
eyes and the bases of the antennae, far outside the possible limits of 
the frons (Fr). 

The part of the postembryonic head that may be defined as the 
frons is the area included between the frontal sutures, where these 
sutures are fully developed (fig. 46 B, Fr). The frontal sutures (fs) 
extend typically from the coronal suture (cs) to the neighborhood 
of the anterior articulations of the mandibles (c, c). The true frontal 
region, therefore, can not include the bases of the antennae, which 



NO. 3 



INSECT IIEAl 



-SNODGKASS 



in-gans belong to the second head segment behind the prostomiuni. 
and acquire their facial positions secondarily by a forward and upward 
migration. \^entrally the frons is limited, and separated from the 





'-at 


S 


-\ Clp 


ry~' 


-m 


^ 

es 


V rLmJ 


/ ^ 
E 






es 


Fr 





Fig. 46. — Modifications in the facial structure of the insect head. 

A, Forficula auricularia. B, Fopillia japonica. larva. C, Ftcrotiidca rihcsi. 
larva, inner surface of front of head. D, J^espa imcidata, well-chitinized_ larva. 
E, Pteronidea ribesi, adult. F. Apis mcUifica. G, Psocus vcnosus. H, Magicicada 
septendecim. I, molted skin of an Aeschna larva. 

Aclp, anteclypeus; Ant, antenna; AT, anterior arm of tentorium; at, anterior 
tentorial pit; c, anterior articulation of mandible; Clp, clypeus ; dt. attachment 
of dorsal tentorial arm to head wall ; cs, epistomal suture ; Fr. frons ; fr, 
" adf rontal " ; Lm, labrum; O, ocellus; .v, suture of Forficula diverging from 
end of coronal suture ; SgR, subgenal ridge ; t, molting split in Aeschna larva 
diverging from end of coronal suture, but is not frontal suture. 

clypeus, by the epistomal suture (fig. 46 B, es), except when this suture 
is lacking. If a median ocellus is present, it is situated in the upper 
angle of the frons (figs. 46 E, 47 B). The muscles of the labrum, 
some of the dilator muscles of the pharynx, and the retractors of the 
mouth angles, when present, have their origins on the frons. By 



122 SMITHSONIAN MISCELLANEOUS COLLECTIONS' VOL. bl 

these characters, especially the position of the median ocellus and the 
origin of the labral muscles, the true frontal region is to be identified 
when the frontal sutures are imperfect or obsolete (fig. 46 E, F, Fr). 

As was shown in the study of the grasshopper (fig. 36 B), the 
frontal region of the face may present a number of secondary lines 
formed by ridges of the inner surface. In the Dermaptera two sutures 
(fig. 46 A, s) diverge widely from the end of the coronal suture {cs) 
and extend outward to the compound eyes. It appears doubtful that 
these are the frontal sutures, for the true frontal region should be 
the smaller triangular area indistinctly defined on the median part of 
the face. 

The clypeus (fig. 46 B, CIp) is a distinct area of the prostomial 
region, and is to be identified by the origin of the dilator muscles 
of the mouth and buccal cavity on its inner wall. It is almost always 
in biting insects separated from the labrum by a flexible suture, and it 
is demarked from the f rons whenever the epistomal suture is present. 
The clypeus is sometimes divided into an anteclypeus and a postclyp- 
eus by a partial or complete transverse suture ; but often the term 
" anteclypeus " is given to a more or less membi'anous area between 
the clypeus and the labrum (fig. 46 G, Aclp), and it is likely that 
regions named " anteclypeus " are not equivalent in all cases. 

The labrum (fig. 46 B, Lm) hangs as a free flap before the mouth. 
It is a preoral lobe of the prostomium characteristic of insects, myria- 
pods, and crustaceans. The insect labrum is usually movable, and is 
provided with one or two pairs of muscles (though both may be ab- 
sent), which, as above noted, have their origin on the frons. The 
labral muscles, therefore, are strictly muscles of the prostomium. 

The principal departure from the typical structure in the pro- 
stomial sclerites arises from variations in the development or in the 
position of the epistomal suture, and from a partial or complete sup- 
pression of the frontal sutures. 

The epistomal suture is the external groove formed incidentally to 
the development of an internal transverse ridge across the prostomial 
area. Since this ridge in generalized insects lies approximately be- 
tween the anterior articulations of the mandibles, its primitive position 
suggests that it was developed to strengthen the lower edge of the face 
between the mandibular bases. The epistomal ridge itself is a con- 
tinuation of the subgenal ridges, and the epistomal suture is, there- 
fore, continuous with the subgenal sutures. In the Ephemerida and 
Odonata, as we have seen, the anterior arms of the tentorium arise 
in the subgenal sutures laterad of the bases of the mandibles. In 
some of the Orthoptera, as in the roach, and in larvae of Coleoptera. 



NO. 3 



INSECT HEAD SNODGRASS 



123 



the tentorial arms have moved forward to a position above the mandib- 
ular articulations, and their external openings, the anterior ten- 
torial pits, appear in these positions (fig. 46 B, at, at). 

In some of the more generalized insects, the epistomal ridge and 
its suture are lacking, as in the roach, and there is then present only 
a single fronto-clypeal sclerite (fig. 47 A, Fr-Clp). In such cases, 
the tentorial pits (at) lie in the anterior extremities of the subgenal 
sutures (sgs), above the anterior articulations (c) of the mandibles. 
Where an epistomal ridge unites the subgenal ridges across the face, 
separating the clypeus from the frons, the tentorial pits may retain 



LmMcls /A ^ Fr-Clp 




A 




Fig, 47.— Diagrams showing variations in the position of the epistomal 
suture (es), and the relations of the frons and the clypeus. 

Aclp, anteclypeus: at, anterior tentorial pit; c, anterior articulation of 
mandible ; CIp, clypeus ; es, epistomal suture ; Fr, frons ; //-, " adfrontal ; Fr-Clp. 
fronto-clypeus ; fs. frontal suture ; h, line of secondary ridge across lower part 
of clypeus ; Lin, labrum ; LmMcls, labral muscles, with origm always on frons ; 
O, median ocellus. 

their positions above the mandibular articulations (fig. 46 A, B, at, 
at) ; but more commonly they move into the epistomal suture (fig. 
47 B). In any case, the tentorial pits identify the epistomal suture, 
when this suture is present. The mandibular articulations (c, c) are 
carried by the ventral margin of the epicranium and are not true land- 
marks of the epistomal suture, as has been pointed out by Yuasa 
(1920), and by Crampton (1925). 

As long as the epistomal suture maintains its direct course across 
the face, no complications arise ; but the suture is frequently arched 
upward, and this shift in the position of the suture extends the clyp- 
eus into the facial region above the bases of the mandibles, and re- 
duces the area of the frons (fig. 47 C). A modification of this kind 



ft 



124 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8[ 

has taken place in the Hymenoptera. In the larval head of Vespa 
(fig. 46 D) the clypeus has clearly encroached upon the area of the 
frons by a dorsal arching of the epistomal suture {cs). In an adult 
tenthredinid (E), the same condition is observed, but the lower parts 
of the frontal sutures {fs) are lost, and the bases of the antennae 
have approached each other mesally, and have constricted the frontal 
area between them. In the adult of Apis (F) the condition is more 
exaggerated — the epistomal suture {es), identified by the tentorial 
pits {at, at), is arched upward almost to the bases of the antennae, 
and the frontal sutures are obsolete. The frontal area (Fr), however, 
is to be identified by the position of the median ocellus, and the points 
of origin of the labral muscles between and just aljove the antennal 
bases. The head of a larval tenthredinid (fig. 46 C) presents a 
specialized condition, for the single large facial plate is here clearly 
a fronto-clypeus, as shown by the origin of the labral muscles on 
its upper parts, and by the origin of the tentorial arms {AT) from 
the ridges at its sides. Evidently, the median part of the epistomal 
ridge and its suture has been suppressed. A similar condition is to 
be observed in some trichopteran larvae. 

A still greater degree in the upward extension of the clypeus is 
shown on the face of a psocid (fig. 46 G). Here the epistomal suture 
{es) is arched high above the tentorial pits {at, at), and the clypeus 
{Clp) becomes the large, prominent, shield-shaped plate of the face 
between the bases of the antennae. The frontal sutures are lacking, 
but the frontal area (Fr) is that between the bifid end of the coronal 
suture and the clypeus, on which is located the median ocellus. A 
weakly chitinized area below the clypeus is sometimes called the 
anteclypeus {Aclp), but it appears to be only a chitinization of the 
connecting membrane between the clypeus and the labrum. 

The clypeus, finally, attains its greatest development at the expense 
of the frons in the Homoptera (fig. 47 D). In the cicada (fig. 46 H), 
the clypeus is the great bulging, striated plate of the face upon which 
arise the dilator muscles of the mouth pump. The dorsal arch of the 
epistomal suture {cs) lies on a level with the antennal bases, and the 
anterior tentorial pits {at, at) are in its upper lateral parts, just above 
the dorsal extremities {c, c) of the mandibular plates (Md). The 
frons is a small, indistinctly defined triangular area {Fr) bearing 
the median ocellus in the adult. It is more strongly marked in the 
nymph, and is cut out by the opening of the frontal sutures at the 
time of the molt. The plate below the principal clypeal sclerite is 
probably an anteclypeus {Aclp), because in some Hemiptera it is not 
distinctly separated from the area above it, but it is questionable if 



NO. 3 INSECT HEAD SNODGRASS 1 25 

it is homologous with the preclypeal area of the psocid (fig. 46 G, 
Adp). The terminal piece in the cicada (H, Lm) that closes the 
groove in the upper part of the labium would appear to be the labrum 
by comparison with Heteroptera. The "mandibular plates" (Md) 
on the sides of the head must be the true bases of the mandibles. Their 
upper ends (c, c) have the same relations to the surrounding parts 
that the anterior mandibular articulations have in biting insects. The 
mandibular bristles are chitinous outgrowths from the ventral pos- 
terior angles of the plates, and the protractor apparatus of each bristle 
in the adult is differentiated from the posterior margin of the mandib- 
ular plate, as the writer has elsewhere shown (1927). 

In the larvae of Lepidoptera, a somewhat different type of modi- 
fication has produced an unusual distortion in the relation between the 
frons and the clypeus. The caterpillar head shows no essential varia- 
tion within the order, but the homologies of the facial structures are 
clear if interpreted by the characters w^hich serve as identification 
marks in the other orders. The triangular facial plate (fig. 50 A) 
thus becomes the clypeus, because the suture (cs) bounding it is identi- 
fied as the epistomal suture by the origin of the anterior tentorial arms 
from its lateral parts (fig. 50 I, AT). Upon this plate arise the 
muscles of the buccal region of the stomodeum. The median part of the 
frons is invaginated and forms the thick internal ridge (Fr) dorsal 
to the apex of the clypeus, which is to be identified as the frons by 
the origin of the labral muscles upon it. The so-called " adfrontals " 
(A, fr) are probably lateral remnants of the frons at the sides of the 
clypeus, and the " adfrontal " sutures are the true frontal sutures 
(fs). That the relations of the plates of the caterpillar's head, as 
thus established, are identical with those in other insects is made clear 
in the diagram given at E of figure 47. The clypeus (Clp) has simply 
extended into the area of the frons, and the median part of the latter 
plate (Fr), bearing the origins of the labral muscles, has been in- 
flected, while its distal parts, the so-called " adfrontals " (fr), maintain 
the original lateral ground of the primitive frontal area. The lower 
]:»art of the clypeus is sometimes strengthened between the ])ases of 
the jaws by a secondary thickening forming a submarginal ridge (h) 
on its inner surface. 

MODIFICATIONS IN THE POSTERIOR VENTRAL REGION OF THE HEAD 

The structural changes in the posterior parts of the head described 
here are associated with an elongation of the postgenal regions, re- 
sulting in the production of a long interval between the foramen 



126 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. Si 



magnum and the posterior articulations of the mandibles. Two dif- 
ferent types of structure follow from this style of modification, one 
shown in adult Hymenoptera and in the larvae of Lepidoptera, the 
other in those orders in which a gular plate is developed. 

The morphology of the posterior surface of the hymenopteran head 
is comparatively easy to understand, for, in the larval stages, the 
rear aspect of the head presents the same structure as does that of 
an adult orthopteron (fig. 36 C). In the head of the larva of Vespa, 
for example (fig. 48 A), the details of the structure are exactly as 
in the grasshopper. There is a distinct postoccipital suture {pos) 
ending below in the invaginations of the posterior arms of the ten- 
torium {pt, pt). The postocciput {Poc) is very narrow, but it forms 
the marginal lip of the head capsule behind the postoccipital suture. 




Cd 




Fig. 48. — Development of the posterior head region in Hymenoptera. 

A, posterior surface of head of larva of Vespa maciilata. C, same of the 
adult. D, corresponding view of head of adult Apis mellifica. 

Cd, cardo ; Lb, labium ; Oc, occiput ; Pge, postgena ; Poc, postocciput ; pos, 
postoccipital suture ; pt, posterior tentorial pit ; St, stipes. 

The labium (Lb) is suspended from the ventral neck membrane, 
and the cardines of the maxillae (Cd) are articulated to the ventral 
cranial margins just anterior to the tentorial pits. 

In the adult wasp (fig. 48 B) the back of the head presents a quite 
different appearance from that of the larva. The foramen magnum 
is greatly contracted and is reduced to a small aperture in the center 
of a broad occipito-postgenal field. It is surrounded by a wide post- 
occipital collar (Poc) set off by the postoccipital suture (pos), in 
which suture are located the posterior tentorial pits (pt, pt). The 
labium (Lb) is detached from the neck and displaced anteriorly 
(ventrally), and the space between its base and the neck is closed by 
mesal extensions of the inner angles of the postgenae (Pge, Pge). 
The articulations of the cardines (Cd) are also far removed from the 
tentorial pits (pt, pt), and are separated from them by the interven- 
ing bridge of the postgenae. In the wasp the postgenal bridge pre- 



NO. 3 INSECT HEAD SNODGRASS I27 

serves a median suture, but in the honeybee (C) the line of union 
between the postgenal lobes is obliterated, and the bridge presents a 
continuous surface in the space between the foramen magnum and 
the fossa containing the bases of the labium and maxillae. In an 
adult tenthredinid {Ptcronidca) , on the other hand, the foramen 
magnum, though greatly reduced in size by the development of a 
wide occipito-postgenal area, is still " open " below, that is, it is closed 
by a narrow remnant of the neck membrane between the approximated 
angles of the postgenae. The labium, however, is displaced ventrally 
and united with the bases of the maxillae. 

In the Hymenoptera, then, there can be little question as to the 
line of evolution that has produced the structure of the back of the 
head in the higher forms. The resulting condition has Ijeen correctly 
observed by Stickney (1923), who says: "In many Hymenoptera 
the mesal margins of the postgenae are fused between the occipital 
foramen and the articulation of the labium." A very similar modi- 
fication of the head has taken place in the caterpillars, as will be shown 
later, in which the parts constituting the " hypostoma " (fig. 51 A, 
Hst) correspond with the postgenal bridge of adult Hymenoptera. 
In either case, an unusual thing has happened in that the labium, after 
being moved forward to unite with the maxillae, has been separated 
from its own segment by the intervention of parts of the first maxil- 
lary segment. If the postgenae are lateral tergal elements of the 
head wall, their ventral union finds a parallel in the prothorax of the 
honeybee, which is completely encircled behind the bases of the legs 
by the prothoracic tergum. 

The modifications in the posterior ventral parts of the head in those 
orders in which a " gula " is developed are difficult to explain if studied 
only in the higher phases of their evolution, but they can be understood 
if traced from forms that show the simpler earlier stages of departure 
from the normal. 

In the Blattidae. the cranium is much flattened, but the essential 
head structure has not been altered, its posterior parts retaining the 
same form as in the less movable head of the grasshoppers. In many 
insects, especially in the Neuroptera and Coleoptera, however, the 
flattened head is not only turned upward on the neck, causing the true 
anterior surface to become dorsal and the mouth parts to be directed 
forward, but the ventral surface of the head has been elongated to 
preserve the vertical plane of the foramen magnum. In such insects 
the bases of the mouth parts become separated from the foramen 
magnum by a wide space, and in this space there appears a median 
9 



128 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

plate called the " gula." The nature of the gula has long been a 
puzzle to entomologists, but Crampton (1921, 1928) has given reasons 
for believing that it is a differentiation of the base of the labium, 
and a few examples taken from the Coleoptera will amply substanti- 
ate this view. 

In a scolytid or scarabaeid beetle larva the structure of the head 
does not differ essentially from that of the grasshopper. The face 
is directed forward, the mouth parts hang downward, and the under 
surface of the head is short. In the scarabaeid larva (fig. 49 A) the 
occipital and postgenal regions terminate in a postoccipital suture 
ipos), in the ventral ends of which are situated the large invagina- 
tions (pf, pt) of the posterior arms of the tentorium. Beyond the 
suture is a narrow postoccipital rim of the cranium (Poc), best de- 
veloped ventrally, where the lateral cervical sclerites (ci') are articu- 
lated to it. The postoccipital ridge is developed on each side of the 
foramen magnum into a broad apodemal plate (PoR), the two plates 
constricting the foramen laterally, and uniting ventrally in the broad 
tentorial bridge, which is concealed in the figure by the ventral part 
of the neck membrane (NMb). The labium, the maxillae, and the 
mandibles of the scarabaeid larva are suspended from the ventral 
edges of the cranium exactly as in the grasshopper (fig. 36 C), but 
the two forms differ by the elongation in the beetle (fig. 49 A) of the 
postgenal margins of the head between the articulations of the car- 
dines (e) and the posterior articulations of the mandibles (a). 

The basal part of the submental region of the labium in the scara- 
baeid larva, Popillia japonica (fig. 49 A), is chitinized to form a 
triangular plate (Smt). This plate is attached to the mesal points of 
the postgenae (Pge), and has its extreme basal angles prolonged be- 
hind the tentorial pits to points (/, /) corresponding with the basal 
articulations of the submentum with the postocciput in an orthopteron 
(fig. 36 C, /). There can be no doubt that this; plate in the beetle head 
is the submentum, or a chitinized basal part of the submentum. It is 
marked by a transverse groove between the tentorial pits ( pt, pf). 

In a silphid larva (fig. 49 B) the general structure of the head is 
similar to that in the scarabaeid larva, but the ventral postgenal mar- 
gins between the articulations of the cardines (c, c) and the mandibles 
(a) are much longer, and the posterior tentorial pits (pt, pt) are 
approximated in the mesally prolonged basal angles of the postgenae. 
The submentum (Smt) is large; its base is narrowly constricted be- 
tween the tentorial pits, which here almost cut off a small but distinct 
proximal area (Gu). The lateral angles of this extreme basal area of 
the submentum are prolonged behind the tentorial pits and become con- 



NO. 3 



INSECT HEAD — SNODGRASS 



129 



tinuoLis with the postocciptal rim of the cranium (Poc), which is set 
oft' by the postoccipital suture (pos) ending ventrally in the tentorial 
pits ipt, pt). 



NMb 





B 



Poc 




Fig. 49. — Evolution of the " gula " in Coleoptera. 

A, Postero-ventral view of the head of a scarabaeid larva, Popillia japonica. 
B, same of a silphid larva, Silpha ohscura. C, ventral surface of an adult 
meloid, Epicauta pcunsylvanica. D, same of a carabid larva, Scaritcs. 

a. posterior articulation of mandible; Cd, cardo; cv, cervical sclerite; e, an- 
terior articulation of mandible ; Gu, gula ; Pge, postgena ; Poc, postocciput ; 
PoR, postoccipital ridge; pos, postoccipital suture; pt, posterior tentorial pit; 
Sml, submentum. 



The characteristic structure of an adult coleopteran head is well 
illustrated in the head of a meloid beetle (fig. 49 C). The form of the 
cranial capsule here differs principally from that of the scarabaeid 
or silphid larva in the lengthening of the postgenal regions between 
the foramen magnum and the articulations of the cardines {e, e). 



T30 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 



The extension of the ventral surface of the cranial wall accommodates 
the head to its horizontal position, and has involved a great elongation 
in that part of the submentum which lies between the posterior ten- 
torial pits {pt, pt) and extends forward to the articulations of the 
cardines {e, c). This region of the submentum is known as the gula. 
In Epicauta (fig. 49 C) the tentorial pits lie at about the middle of the 
lateral margins of the gula, and the ventral ends of the postoccipital 
suture {pos) are, consequently, turned anteriorly and lengthened in 
the same direction behind the pits. The ventral parts of the post- 
occipital suture, terminating in the tentorial pits, now become the so- 
called " gular sutures." It is evident that the large gular region in the 
adult meloid head (fig. 49 C) lying posterior to the tentorial pits 
and continuous basally with the postoccipital rim of the cranium 
(Poc) is produced from the small but corresponding area in the larval 
silphid head (B, Gu) , and that this area, in turn, is merely the basal 
strip of the submentum in the scarabaeid larva (A, Sint), attached to 
the postocciput by its lateral extremities (/, /). 

In adult Coleoptera the distal end of the gula may be dififerentiated 
as a " pregula " or " gular bar " (C, Pgu). It supports the terminal 
part of the original submental plate (Suit), which lies between the 
bases of the maxillae, and which, in a restricted sense, is usually called 
" the submentum " by coleopterists. The pregular region may fuse 
laterally with the " hypostomal " regions of the postgenae, and in 
other ways the more primitive structure may become so obscured that 
the relations of the parts are difficult to determine except by studying 
them in a gradient series of simpler forms. The comparative studies 
made by Crampton (1921, 1928) on the gula in various orders show 
fully its numerous variations, and demonstrate its origin from the 
proximal part of the primitive submental plate. Stickney (1923) also 
has well illustrated the structure of the gula and associated parts in 
a large number of coleopteran forms. Stickney fails to recognize, 
however, that the " gular sutures " are direct continuations of the 
ventral ends of the postoccipital suture, and that, therefore, the gular 
plate between them must be the basal part of the submentum. He 
would explain the gular bridge in the Coleoptera as a product of the 
ventral fusion of the edges of the postgenae, and the gular sclerite 
as a plate cut out of this newly-formed region by the anterior exten- 
sion of the " gular sutures." As we have seen, the ventral bridge of 
the cranial walls is formed in this manner in the Hymenoptera (fig. 
48), as Stickney has pointed out, but in the Hymenoptera the ten- 
torial pits have remained at the sides of the foramen magnum, and 
the labium has lost its original connection with the postoccipital region. 



NO. 3 INSECT HEAD SNODGRASS I3I 

The facts are quite otherwise in the Coleoptera, for here the labium 
retains its postoccipital connections, and its base has been drawn out 
between the lengthened postgenal margins to form the gula. 

In certain Coleoptera the postgenal margins do become closely ap- 
proximated (fig. 49 D), but, in such cases, the gula is compressed be- 
tween the postgenae, and sometimes almost obliterated. The gular 
sutures may then be partially or wholly united into a median gular 
suture, with which are closely associated the two tentorial pits (pt, 
pt). Intermediate stages of this condition are well shown in some 
of the Rhyncophora, in which the head is drawn out into a " snout." 

In the Neuroptera, both larvae and adults, and in larval Trichoptera, 
a gular plate is developed showing essentially the same structure and 
variations of form as in the Coleoptera. The gular structure has been 
described in various members of these orders and others in addition 
to the Coleoptera by Crampton (1921, 1928). In the Termitidae, 
Crampton shows, the gular region of the submentum may be very 
much elongated, and in the soldier of Termopsis its margins become 
united with the lengthened edges of the postgenae to fomi a typical 
gular plate. 

The question of the derivation of the gula, the answer to which is, 
that the gula is a part of the submental region of the labium, is not 
to be confused with the question as to the origin of the submentum 
itself. The various views concerning the nature of the submentum 
have been already discussed in an earlier section of this paper (page 
yy), and the writer will reiterate here only his own personal opinion 
that, since the submentum in generalized insects is attached laterally 
to the postoccipital tergal region of the head, it comprises the basal 
parts of the second maxillary appendages, to which, however, there 
may be added a median field of the sternum of the corresponding seg- 
ment. If the submentum is regarded as entirely the labial sternum, 
then the sternum becomes suspended directly from the tergum of its 
segment, and bears the appendages — Sl condition so at variance with 
ordinary morphological relations as to discredit the premises from 
which it is deduced. 

VII. THE HEAD OF A CATERPILLAR 
The caterpillars are remarkable for their standardization of struc- 
ture. In none of the other larger groups of insects is there such uni- 
formity in fundamental organization as in the larvae of the Lepidop- 
tera. Some species are superficially specialized, but apparently there is 
no " generalized " caterpillar. Ontogenetically, the caterpillars prob- 
ably represent a stage below that of the larvae of Neuroptera, and of 



132 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 



the larvae of the more generaHzed adult Coleoptera (Adephaga), 
since the young of these insects are closer in form to that of a typical 
adult insect. The caterpillars show primitive conditions in the origin 
of the antennal muscles on the walls of the cranium, in the musculature 
of the thoracic legs, in the monocondylic leg joints, in the dactylopo- 
dite-like end segments of the legs, and in the retention of the abdominal 
" legs," if these organs are remnants of true abdominal appendages, 
as they appear to be. The general form of the alimentary canal, of 
the tracheal system, and of the nervous system are fairly generalized, 
though the brain is specialized by an extreme condensation of its 
ganglia. On the other hand, the head, the maxillary appendages, the 
muscle sheath of the alimentary canal, and the body musculature are 
all highly specialized. While the form of the caterpillar's body is 
worm-like, it is not to be supposed that it represents a worm stage 
or even a primitive stage in the insect ancestry, for the structure of 
the head shows that the caterpillar belongs to the highly evolved stage 
of the pterygote insects. The caterpillar's form is merely one that 
adapts the insect to a wide feeding environment. The extremely com- 
plicated body musculature must be regarded as acquired through an 
excessive multiplication of the segmental muscles to give unlimited 
mobility to a soft-bodied animal. The fly maggot likewise has an 
intricate body musculature, but of quite a different pattern from that 
of the caterpillar. 

STRUCTURE OF THE HEAD CAPSULE 

The caterpillar head is an example of the type of head structure in 
which the lower genal and postgenal regions of the cranium (fig. 51 E) 
are lengthened to give a long ventro-lateral area on each side between 
the foramen magnum and the posterior articulation of the mandible. 
The facial aspect of the head (fig. 50 A) is characterized by the ex- 
tension of the clypeus into the area of the f rons, and by the invagina- 
tion of the median part of the frons dorsal to the clypeus. 

The prominent triangular plate so characteristic of the facial aspect 
of a caterpillar's head is unquestionably the clypeus (fig. 50 A, B, C, 
F, H, Clp), though it has usually been called the " frons." Its margins 
are defined internally by a strong V-shaped ridge (E, I, ER), the in- 
verted apex of which is continued into a thick median ridge of the 
dorsal wall of the cranium. From the arms of the V-ridge arise the 
anterior tentorial apophyses {AT), and the latter identify the V-ridge 
as the epistomal ridge {ER). The space between the diverging arms, 
therefore, is the true clypeus {Clp). It has already been shown that 
the clypeus in other orders of insects may be extended into the facial 
region dorsal to the mandibular articulations (figs. 46 D, F, G, 47 C). 



NO. 3 



INSECT HEAD SNODGRASS 



133 



Further evidence that the area thus designated the clypeus in the 
lepidopteran larva is the true clypeal area, and not the frons, is given 




Fig. 50. — Head structure of caterpillars : anterior cranial wall, labrum, 
antenna, and mandibular muscles. 

A, anterior surface of head of Lycophotia {Peridroma) margaritosa. _B, 
same of Thrydoptervx cphemeraefonnis. C, same of Sibeiic stimulca. showing 
areas of origin of "mandibular muscles (4, 5a). D, antenna of Malacosoma 
amcricana, left, anterior view. E, interior view of anterior wall of head of 
Prionoxyshis robiniae (Cossidae), with labral muscles and adductor of left 
mandible in place. F, anterior surface of head of Mnemonica aurocyanea. G. 
labrum of Lycophotia maryaritosa, anterior view, showing muscle insertions. 
H, fronto-clypeal area of same. I, inner view of same. 

AT, anterior arm of tentorium; c, anterior articulation of mandible; Clp. 
clypeus ; ER, epistomal ridge ; cs, epistomal suture ; Fr, frons ; jr, " adf rontal " ; 
fs, frontal suture; h, submarginal thickening of clypeus; Lm, labrum; Md, 
mandible; Nv, antennal nerve; Tra, antennal trachea. 

by the origin of the clypeal dilator muscles of the stomodeum upon it 
(fig- 55. 20, 21). Finally, it is to be observed, the muscles of the la- 
brum, which, in all cases where the identity of the facial plates is clear, 



134 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 



arise on the frons, are never attached to the triangular plate of the 
caterpillar face, but take their origin from the median ridge dorsal 
to it (fig. 50 B, E, /). In many caterpillars the lower part of the clyp- 
eus is strengthened by an internal sul)marginal thickening (E, I, h) 
forming a bracing ridge between the articulations of the mandibles 
(c, c). 

The frontal area of the head, as has been shown, is to be identified 
by the origin of the labral retractor muscles upon its inner surface 
(fig. 47 B, C). In the caterpillar the labral muscles arise either upon 
the median internal ridge of the cranium that extends between the apex 
of the posterior emargination of the vertex and the apex of the clyp- 
eus, or upon the dorsal bifurcations of this ridge that are continued 
into the margins of the vertical emargination (fig. 50 B, E, 53 E, /). 
This ridge, then, is at least a part of the frons. It is formed by a deep 
inflection of the median line of the cranium dorsal to the apex of the 
clypeus, which appears externally as a median suture (fig. 50 A, B, C, 
H, Fr). In a softened specimen this frontal invagination can often be 
widely opened, when it is seen that its inflected surfaces are continuous 
with the so-called " adfrontal " strips lying laterad of the clypeus and 
extending ventrally to the bases of the mandibles. The sutures, 01 
membranous lines, along the outer margins of the " adfrontals " thus 
become the true frontal sutures (fig. 50 A, H, I, fs). 

The frontal region of the caterpillar, therefore, includes the invag- 
inated frontal groove (fig. 50 A, E, Fr), the " adfrontals " (fr), and 
perhaps the apical margins of the vertical emargination. When the 
mature caterpillar sheds its skin at the pupal molt, the head cuticula 
splits along two lines, which, beginning at the notch of the vertex, 
follow the external lips of the median frontal invagination and then 
diverge along the " adfrontal " sutures to the bases of the mandibles. 
An elongate piece is thus cut out which includes the median frontal 
inflection, the " adfrontals " and the clypeus. In some caterpillars the 
molting cleft follows only one of the adfrontal sutures, the other re- 
maining closed. 

The median part of the vertex in the caterpillar's head is obliterated 
•by the dorsal emargination, and the angle of the emargination usually 
extends into the frontal invagination (fig. 50 I) ; in some cases the 
notch is so deep that the latter is reduced to a very small area dorsal 
to the apex of the clypeus (F). 

The labrum of the caterpillar (fig. 50 A, B, Lin) is commonly sep- 
arated from the lower edge of the clypeus by a wide, flexible membran- 
ous area. Some writers, having mistakenly identified the true clypeus 
as the frons, have regarded this membranous area as the clypeus, 



NO. 3 INSECT HEAD SNODGRASS I35 

but the error of this interpretation is shown by the fact that none 
of the stomodeal muscles arise upon the membrane, the clypeal dila- 
tors having their origin on the triangular plate above. The caterpillar 
labrum has but a single pair of muscles : 

/. — Retractor muscles! of the lahrmn (figs. 50 E, G, 53 E). — A pair 
of long slender muscles arising on the inflected frons (figs. 50 E, 53 E, 
Fr) ; inserted by long tendons on bases of tormae (figs. 50 G, 53 E) 

The ventral surface of a caterpillar's head presents a number of 
secondary modifications that, at first sight, somewhat obscure the basic 
structure ; but, when the general head " landmarks " are once recog- 
nized, it is not difficult to see that the fundamental structure is no 
difl:'erent from that in an orthopteroid head. 

As we have noted, the caterpillar head is characterized by an elon- 
gation of the postgenal regions between the foramen magnum, or the 
end of the neck membrane (fig. 51 E, NMh) , and the posterior articu- 
lations of the mandibles (a). On each side, a posterior median part 
of the postgena (A, E, Hst) is separated from the more lateral post- 
genal region (Pge) by a suture (/). 

The median area thus set off is called the hypostoma {Hst), and the 
inner angles of the two hypostomal areas are approximated and 
sometimes united on the median line behind the base of the labium, 
which is thus separated from its usual basal connection with the neck 
membrane, or with the postoccipital rim of the cranium. In this 
manner a condition has been evolved which is almost a replica of that 
in the head of adult Hymenoptera (fig. 48 B, C), except that in the 
latter the hypostomal areas are not separated from the rest of the 
postgenal regions. 

In some caterpillars a well-developed subgenal ridge (fig. 51 D, 
SgR) follows the outer margin of the membranous area of the an- 
tennal base from the anterior articulation of the mandible (c) to the 
posterior (a), and is then continued along the anterior mesal margin 
of the hypostoma (Hst). Some entomologists distinguish the part 
of the subgenal ridge that skirts the mandibular area as the " pleuro- 
stomal ridge," or " pleurostoma," and that part which follows the 
hypostomal margin as the " hypostomal ridge." The external suture 
that defines the hypostomal area on each side (E, ;) forms internally 
a strong ridge (D, ;) extending from the subgenal ridge at the pos- 
terior mandibular articulation (a) to the postoccipital ridge (PoR). 
The subgenal ridge, especially its hypostomal part, is lacking or but 
weakly developed in some caterpillars (C), but the ridge of the 
hypostomal suture (;) is always well developed, and apparently serves 
to brace the genal area between the mandible and the posterior rim 



136 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 81 



of the head. The maxillae are suspended in the usual manner by the 
articulations of the cardines against the margins of the hypostomal 
areas of the postgenae (C, Cd, E, e). 



NMb 




(2 Sg-R-^ Hst t=^ D 



Fig. 51. — Structure of the posterior and ventral parts of the head of a 
caterpillar. 

A, postero-ventral view of head of a noctuid (Lycaphotia iimrgaritosa). B, 
dorsal view of»same. C, interior view of postgenal and hypostomal regions, 
showing posterior arm of tentorium (PT), and articulation of cardo (Cd). D, 
inner face of same region in Malacosoma americana. E, ventral view of right 
half of cranium, with mandible and antenna, of Estigmene acraea. 

a, posterior articulation of mandible; Ant, antenna; 4AP, base of adductor 
apodeme of mandible; AT, anterior arm of tentorium; c, anterior articulation 
of mandible ; Cd, cardo ; dap, dorsal apodemal plate of postoccipital ridge ; e, 
articulation of cardo to cranium; FrR, frontal ridge; Hst, hypostoma ; /, line 
of base of neck membrane; j, hypostomal suture, hypostomal ridge ; Lb. labrum : 
Md, mandible; Mx, maxilla; NMb, neck membrane; Pge, postgena ; PoR, post- 
occipital ridge; PT, posterior arm of tentorium; Tnt, transverse bar of ten- 
torium ; vap, ventral apodemal plate of postoccipital ridge. 



The foramen magnum is extraordinarily large in the caterpillar, 
being almost as wide as the cranium, and is extended forward dorsally 
in the median notch of the vertex (fig. 51 A). The postoccipital ridge 
{PoR) is inflected from the rear margin of the cranial walls, there 



NO. 3 INSECT HEAD SNODGRASS I37 

being no perceptible chitinization beyond it to form a postoccipital 
rim in the neck region. The postoccipital ridge gives origin to plate- 
like apodemes that constrict the actual opening of the head cavity into 
that of the neck. Usually there is a pair of dorsal apodemes (A, B. 
dap) in the notch of the vertex, and a pair of larger ventral apodemes 
(A, D, E, vap) arising from the postgenal and hypostomal parts of 
the postoccipital ridge. The apodemes vary much in size and shape in 
different species, but those of the ventral pair are usually the larger 
and the more constantly developed. The apodemes furnish surfaces 
of attachment for the anterior ends of prothoracic muscles inserted 
on the back of the head (fig. 57 A, C). In the caterpillars the foramen 
magnum is crossed laterally by oblique foraminal muscles, which are 
the following : 

2. — Muscles of the foramen magnum (figs. 51 E, 57 A). — Attached 
below on each side to ventral postoccipital apodeme (fig. 51 E, vap) 
laterad of posterior root of tentorium ; spreading dorsally and laterally, 
sometimes as a broad fan (fig. 57 A), to the dorso-lateral parts of 
postoccipital ridge. The foraminal muscles are of the nature of the 
transverse muscles of the intersegmental folds in the body of the 
caterpillar. From their position it would appear that they must pro- 
duce a tension on the hypostomal regions of the head wall. Foraminal 
muscles are not present in insects generally. 

The tentorium of the caterpillar is a simple structure consisting of 
two slender longitudinal bars, and of a delicate transverse posterior 
bridge. The longitudinal bars, which represent the anterior arms of 
the tentorium (fig. 53 D, E, AT), arise from the lateral parts of the 
epistomal ridge at the sides of the clypeus (fig. 50 E, I, AT). They 
extend horizontally through the head (fig. 53 E), and are united 
posteriorly with the ends of the posterior bridge (figs. 51 A, C, E, 
53 D, Tnt). The bridge represents the united median parts of the 
posterior tentorial arms (fig. 51 A, C, PT), the origins of which (E, 
pt) are at the posterior angles of the hypostomal plates in the deep 
inflections that form the inner ends of the ventral postoccipital apo- 
demes {vap). The positions of all the tentorial roots in the caterpillar, 
thus, are identical with those of the tentorial roots in an orthopteroid 
head, notwithstanding the considerable alterations which the surround- 
ing parts have suffered. 

THE ANTENNAE 

The antennae are much reduced in all caterpillars, being so small 
by comparison with the adult organs that the latter are forced to de- 
velop by recession, and during the propupal stage their tips only lie 
within the antennae of the larva. The antennae of the caterpillar are 



138 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 



situated on membranous areas just laterad of the bases of the man- 
dibles, while the antennae of the adult arise from the facial region 
above the compound eyes. The ventro-lateral position of the larval 
antennae, therefore, appears to be a primitive character in the cater- 
pillars. 

Each antenna of the caterpillar consists of three segments, of which 
the middle one is usually the largest, the proximal segment being 
often reduced to a mere basal ring (fig. 51 E, Ant), and the terminal 
one appearing as a minute apical papilla of the second. The mem- 
lirane of the antennal base may form a large mound with the antenna 
retractile into it, or sometimes a long cylindrical projection simulat- 
ing a basal segment (fig. 50 C). A hypodermal fold projects inward 
from the base of the antenna (fig. 50 D) which receives the antennal 
nerve and trachea. Each antenna is moved by a single set of muscle 
fibers, which are : 

J. — TJie retractor muscles of the antenna (fig. 50 B — F). — -A group 
of slender fibers arising on the parietal walls of the cranium laterad 
of adf rontal area ; inserted on anterior inner angle of base of proximal 
antennal segment. Extension of the antennae is probably effected by 
blood pressure from within the head. 



THE MANDIBLES 

The mandibles of the caterpillar are typical insect jaws suspended 
from the lower margins of the cranium by a hinge line sloping down- 
ward posteriorly, with well-developed anterior and posterior articula- 
tions. The anterior articulation of each mandible consists of a condyle 
on the cranial margin placed just laterad of the clypeus (fig. 52 A, c), 
received into a socket on the base of the jaw ; the posterior articulation 
(a) is the reverse, consisting of a socket on the cranial margin receiv- 
ing a condyle of the mandible. As in all insects, the articular points 
of the jaw lie outside the membrane that connects the base of the 
mandible with the head. A line between the two articulations divides 
the base of the jaw unequally (fig. 52 B), the larger part being mesad 
to the axis. 

The muscles of the mandibles are inserted on large but weakly 
chitinized apodemal inflections arising at the outer and inner margins 
of each jaw. The muscles take their origin on the walls of the cranium 
and on the ventral apodemes of the postoccipital ridge. Their fibers 
occupy most of the cavity of the head, and the cranial hemispheres 
appear to model their form on that of the bases of the great adductor 
muscles of the jaws. 



NO. 3 



INSECT HEAD SNODGRASS 



139 



4. — The abductor muscles of the mandible (figs. 50 C, 52 B). — A 
group of fillers, small by comparison with the adductor group, arising 
on lower lateral and posterior walls of cranium, and on ventral apo- 
deme of postoccipital ridge laterad of posterior root of tentorium ; 
fibers converging ventrally, anteriorly, and mesally to insertion on 
abductor apodeme of mandible. 

5. — The adductor muscles of the mandible (figs. 50 C, E, 52 B, 53 
E). — An enormous mass of fibers disposed in two sets (figs. 52 B, 
53 E, 5a, 3b). The fibers of one group arise from almost entire dorsal, 
anterior, lateral, and posterior walls of corresponding half of epi- 
cranium above the ocelli (figs. 50 C, E, 53 E, 3a) ; they converge down- 
ward upon both surfaces of the broad, adductor apodeme of mandible. 
The fibers of the other group (figs. 52 B, 53 E, 5/;) arise on ventral 
apodeme of postoccipital ridge (fig. 53 E, vap) mesad of bases of 

Clp 




Fig. 52. — Mandibles of a caterpillar. 

A, mandibles and antennae of Estigmenc acraea, ventral view. B, left mandible 
of a noctuid, with bases of muscles, dorsal view. 

a, posterior articulation of mandible; Ant, antenna; c, anterior articulation of 
mandible ; Clp, edge of clypeus ; Mds, mandibles ; 4, abductor muscle of mandible ; 
^a, fibers of adductor arising on wall of cranium; 5/', adductor muscles arising 
on ventral apodeme of postoccipital ridge (see fig. 53 E). 

abductor fibers, and extend horizontally to posterior edge of adductor 
apodeme of mandible. 

The obliquity of the mandibular axes causes the points of the jaws 
to turn upward and somewhat posteriorly during adduction. When 
the mandibles are closed, the teeth on the cutting edges of the two 
jaws are opposed to each other (fig. 52 A), not interlocked ; but usually 
one mandible closes first and its toothed edge passes inside that of the 
other. Live caterpillars examined by the writer always closed the right 
mandible over the left, and species of several families preserved in 
alcohol were found to have the jaws in the same position. 



THE MAXILLAE AND LABIUM 



The basal parts of the maxillae and labium are united, and their 
chitinous areas are reduced or variously broken up into small plates 
(figs. 51 A, 53 A), which may dififer much in dififerent species. With 



140 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 81 

the anterior wall of the labium, apparently, is united also the hypo- 
pharynx (fig. 54 D, Hphy), and the duct of the silk gland opens 
through a hollow spine, the spinneret, at the tip of the labium. 

Each maxilla includes a cardinal area (fig. 53 A, Cd), a stipital 
area {St), both united with the basal part of the labium, and a free 
terminal lobe {Lc) , which appears to be the lacinia. A maxillary palpus 
is lacking. The area of the cardo- includes one principal sclerite (fig. 
53 A, B, E, F, Cd), and generally one or two accessory plates (A, E, 
F, k, k). The principal sclerite is always articulated to the hypostomal 
margin at a point (c) corresponding with the articulation of the cardo 
to the cranium in orthopteroid insects. The area of the stipes (St) 
is variously chitinized, or unchitinized, but it always preserves the 
ridge (q) of its inner margin, upon which are attached all the stipital 
muscles. The homology of the terminal lobe of the maxilla is difficult 
to determine. 

The musculature of the maxilla of a caterpillar comprises muscles 
pertaining to its three parts, most of which are comparable to the 
maxillary muscles of the grasshopper or other generalized insects, 
though there is little similarity in the general appearance of the struc- 
ture in the two cases. The cardo, in the caterpillar, is provided with 
two or three muscles (fig. 53 B, E, F. 6, 7, 8), all of which arise on 
the anterior arm of the tentorium (D, E), and, therefore, represent 
the tentorial adductors of the cardo in orthopteroid insects. The usual 
cranial muscle of the cardo (fig. 25, /, fig. 40 C, 10) is lacking in the 
caterpillar. The stipes is provided likewise with tentorial adductors 
(fig. 53 B, D, E, F, g, 10, 11) inserted on its mesal chitinous ridge {q). 
The terminal maxillary lobe is moved by muscles that arise within the 
stipes (B, F, 12, jj), and also by a long muscle (B, 14) having its 
origin in the posterior angle of the hypostomal plate (Hst) of the 
epicranium. These three muscles are inserted upon a basal sclerite 
in the ventral wall of the maxillary lobe (A, B, /). The first two 
suggest the ordinary stipital muscles of the lacinia, but the third (14) 
appears to have no homologue in more generalized insects, since the 
usual cranial flexor of the lacinia (fig. 30 B, ficc) is inserted on the 
median angle of the latter. The insertion of the three muscles on a 
single sclerite in the base of the maxillary lobe leaves no evidence to 
indicate the presence of a galea, and suggests that the lobe is the lacinia 
alone, complicated in form by the development of large sensory 
papillae. Certainly, the musculature of the lobe shows that none of 
the papillae can be a palpal rudiment. 



NO. 3 



INSECT HEAD SNODGRASS 



141 




Fig. 53. — Maxilla, labium, and silk press of a caterpillar. 

A, Estiijmenc acraca, maxillae and labium, with hypostomal plates of head, 
posterior (ventral) view. B, internal view of left maxilla and hypostomal 
region of same, showing muscles. C, Malacosoma americana, distal part of 
labium and hypopharynx, lateral view, showing silk press and muscles. D. 
Lycophotia mar g aril osa, muscles of maxillae, labium, and hypopharynx, internal 
(dorsal) view. E, the same, right side of head, internal view, showing muscles 
of labrum, mandible, maxilla, and labium. F, cardo and lateral parts of stipes 
of right maxilla, showing bases of muscles, dorsal (anterior) view. (Compare 
with E.) 

a, anterior articulation of mandible; AT, anterior arm of tentorium; Cd, 
cardo ; Clp, clypeus ; dap, dorsal apodeme of postoccipital ridge ; c, articulation 
of cardo with cranium; Fr. f rons ; /;, submarginal ridge ot clyjeus : Hpliy. 
hypopharynx ; Hst, hypostoma ; /, hypostomal suture ; k, accessory plates of 
cardo; l, basal sclerite of lacinia ; Lc, lacinia ; Lm, labrum; Md, mandible; Mt, 
mentum; NMb, neck membrane; PT, posterior tentorial arm; pt, posterior 
tentorial pit ; q, ridge on inner edge of stipes ; r, articular nodule between 
end of stipital ridge (q) and mentum; SID. silk gland ducts; Suit, submentum ; 
Spf, spinneret; St, stipes; Tut. transverse bar of tentorium; vap, ventral apodeme 
of postoccipital ridge. 



W' 



142 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 81 

The muscles of the maxilla may be enumerated as follows, and 
they will probably be found to dififer but little in different species of 
caterpillars : 

6. — First adductor of the cardo (fig. 53 B, D, E, F). — Origin on 
posterior end of anterior arm of tentorium (AT) ; goes ventrally 
to insertion on base of cardo. 

7. — Second adductor of the cardo (fig. 53 B, D, E, F). — Origin 
anteriorly on tentorial arm (D, E) ; insertion on distal end of cardo. 

8. — Third adductor of the cardo (fig. 53 D, E, F). — This muscle 
found in noctuid larvae, perhaps a subdivision of 7. Origin anterior 
to 7 on tentorial arm (D, E) ; insertion on accessory plate (E, F, k) 
mesad to the articulating sclerite of cardo {Cd). 

9. — First adductor of the stipes (fig. 53 B, D, E, F). — Arises near 
anterior end of anterior tentorial arm (D. E) ; goes obliquely ventrally 
and posteriorly to insertion on marginal ridge (B, D, E, F, q) of 
stipes. 

70. — Second adductor of the stipes .(^g- 53 B, D, E, F). — Origin 
at anterior end of tentorial arm, just before p (D, E) ; insertion on 
stipital ridge (D, E, F, q) anterior to p. 

II. — Third adductor of the stipes (fig. 53 B, D, E, F). — Arises pos- 
teriorly on anterior tentorial arm, just before first adductor of cardo 
(6) ; goes obliquely ventrally and anteriorly (D, E), internal to 7, 8, 
p, and 10, to insertion on anterior end of stipital ridge (B, D, E, F, q) 

12. — External retractor of the lobe (fig. 53 B, F). — Origin on 
base of stipital ridge {q) ; insertion laterally on basal plate (A, B, /) 
of terminal lobe of maxilla. 

/?. — Internal retractor of the lobe (fig. 53 B. F). — Origin on 
base of stipital ridge (q) ; insertion mesally on basal plate (A, B, /) 
of terminal lobe of maxilla. 

14.- — Cranial abductor of the lobe (fig. 53 B). — Origin in basal 
angle of hypostomal plate of epicranium (Hst) ; insertion on outer 
end 'of basal plate (/) of terminal lobe of maxilla. A corresponding 
muscle is not present in orthopteroid insects. 

The labium of the caterpillar (fig. 53 A) lies between the maxillae. 
The broad membranous surface of its large submental region is united 
on each side with the marginal ridges (q) of the stipites, and its 
basal part is continuous laterally with the membrane of the cardinal 
areas. Proximally the labium may be continuous with the neck mem- 
brane (NMb) between the approximated ends of the hypostomal 
plates (Hst), but, when the latter are united, the labium becomes 



NO. 3 



INSECT HEAD SNODGRASS 



143 



separated from the neck. A large suljniental plate occupies the median 
basal part of the submental region in some species (A, Smt). 

The distal, free lobe of the labium probably represents the mentum 
and ligula of other biting insects, combined with the hypopharynx, 
which forms its anterior surface (fig. 54 A). Evidence of this in- 
terpretation is found in the fact that the labial and hypopharyngeal 



Hphy, 




SID 



-- Pr 




Hphy 




Fig. 54. — Distal part of labium, hypopharynx, and silk press of a noctuid 
caterpillar. 

A, mentum and hypopharynx, with silk press partly exposed, lateral view. 
B, the same, dorsal view. C, the same, posterior view, showing support on arms 
of stipites iq, q). D, lateral view, showing muscle attachments. 

Hphy, hypopharynx ; Mt, mentum ; Pr, silk press ; q, q, ridges of stipes ; r, r, 
articular nodules between stipital arms and mentum ; SID, silk duct ; Spt, 
spinneret. 

muscles are inserted on the base of the lobe (figs. 53 C, D, 54 C, D, 
15, 16), and in the position of the spinneret (fig. 54 A, D, Spt), which 
contains the opening of the silk duct (salivary duct), the latter being 
normally situated between the labium and the hypopharynx (fig. 18 
D, SIO). 

The mental region of the mento-hypopharyngeal lobe appears to 
be that occupied by the large proximal plate (fig. 53 A, Mt) that em- 
10 



144 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 



braces the base of the lobe ventrally and laterally, but which is not 
continued across the hypopharyngeal surface (figs. 53 C, 54 A, C, D, 
Mt). This plate is supported upon the distal ends of the ridges of 
the stipites (fig. 54 C, D, q, q), which are turned forward and artic- 
ulated with the dorsal arms of the mentum (Mt) by small, chitinous 
nodules (r, r). By this mechanism, the mentum-hypopharynx, which 
carries the spinning apparatus, is freely movable on a transverse axis 
between the ends of the supporting stipital ridges. The motion in a 
vertical plane is the only movement that can be given to the spinning 
apparatus, except by the action of the entire head ; but the head of 
the caterpillar is highly mobile by reason of the great number of mus- 
cles inserted upon its posterior margin (fig. 57). The musculature 
of the mentum-hypopharynx, or spinning organ, is as simple as its 
mechanism, consisting of two pairs of muscles, as follows : 

75. — Reductors of the spinning organ (figs. 53 C, D, E, 54 C, D) — 
A pair of double muscles arising at posterior ends of tentorial arms 
(fig. 53 D, E) ; converging ventrally and anteriorly to insertions on 
ventral edge of mentum (figs. 53 C, E, 54 C, D, Mt). These muscles 
probably represent the mento-tentorial muscles of orthopteroid insects 
(fig. 40 D, ^5), which are primitive adductors of the second maxillae. 

i6.—Productors of the spinning organ (figs. 53 C, D, 54 C, D). — 
A pair of broad muscles arising medially on transverse bridge of ten- 
torium (fig. 53 D, Tnt), diverging ventrally and anteriorly to base of 
hypopharynx (figs. 53 C, D, 54 C, D, Hphy). These muscles are prob- 
ably the retractors of the hypopharynx in orthopteroid insects (fig. 

41, J'?)- 

The silk press of the caterpillar is a special development of the 
common duct of the labial glands (here, the silk glands). The deeply 
invaginated dorsal wall of the organ exerts a pressure on the silk ma- 
terial, which is regulated by two sets of opposing muscles that, prob- 
ably acting together, effect a dilation of the lumen of the press by 
elevating the invaginated roof. The muscles of the press arise within 
the mentum, and the two sets may be distinguished as follows : 

//, 18. — Dorsal muscles of the silk press (fig. 54 A, B, C). — Two 
lateral series of muscles, the number on each side varying in different 
species of caterpillars, arising on dorsal arms of mentum ; converg- 
ing to insertions on chitinous raphe in dorsal (anterior) wall of press. 

ip. — Ventral muscles of the silk press (fig. 54 A, B, C). — Origin 
in ventrolateral parts of mentum ; insertion on dorso-lateral edges of 
silk press. These muscles are antagonists to the dorsal muscles, since 
the fibers of the two sets oppose each other in the crossed lines of an X 






NO. 3 



INSECT HEAD SNODGRASS 



145 



(fig. 54 C) ; but in function the ventral muscles are probably accessory 
to the dorsals by counteracting the pull of the latter on the press. 

It is difficult to discover a parallelism between the muscles of the 
silk press in the caterpillar and muscles of the labium in other insects. 
However, it may be possible that the two sets of muscles in the labium 
of the grasshopper (fig. 40 D, 26, 2y) inserted on the salivary cup {v) 
are the prototypes of the silk press muscles, though their insertion 
points are ventral instead of dorsal. 

THE STOM ODEUM 

The stomodeum of the caterpillar (fig. 55) is diflferentiated into 
four parts. The first part is a bucco-pharyngeal region {BuC, Phy) ; 



Cr 







BuC- 



^./ 



Fig. 55. — Anterior part of the stomodeum of a noctuid caterpillar, showing 
muscles of the stomodeal wall, and the dilator muscles arising in the head. 

a-m, muscles of stomodeal wall ; BnC, buccal cavity ; Cr, crop ; OE, oesoph- 
agus ; Phy, pharynx ; 20-23, muscles of buccal region, arising on _ clypeus ; 
24-27, dorsal dilators of anterior pharyngeal region; 28-30, dorsal dilators of 
oesophagus (posterior pharyngeal region) ; 31-36, ventral dilators. 

the second, a cylindrical tube with strong transverse muscle rings, 
constitutes an oesophagus (OE) in the caterpillars, but it evidently 
corresponds with the posterior section of the pharynx in Orthoptera ; 
the third part is the large sack-like crop (Cr) ; the fourth is the con- 
stricted posterior region of the stomodeum (fig. 56 F, Pvent), which 
may be termed the proventriculus, though it has no special develop- 
ment of the lining intima, such as usually distinguishes the proven- 
tricular region in other insects. 

The muscular sheath of the entire alimentary canal of the caterpillar 
is strongly developed, and in some parts becomes highly complicated 
in structure. The alimentary muscles are particularly strong in the 
noctuids, and the following descriptions are based mostly on Lyco- 
photia margaritosa. 



146 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 81 



The lateral walls of the bucco-pharyngeal region are marked on each 
side by an oblique ridge (fig. 55), formed by a specially chitinized 
groove of the intima, which gives a firm line of insertion for the ex- 
ternal muscles. The latter consist of thick, broad bands of strongly 
fibrillated muscle tissue, for the most part lying in one plane, though 
varying in position from transverse to longitudinal. The anterior- 
most muscles consist of two dorsal arcs (a, /?), and of a corresponding 
wide ventral arc (d), their ends inserted laterally on the oblique 
ridges. This part of the stomodeum may be defined as the buccal 
region because its dilator muscles (20-2^) have their origins on the 
clypeus. The anterior end of the pharyngeal region following is cov- 
ered dorsally by a broad transverse muscle (c) attached laterally on 
the oblique ridges. The frontal ganglion lies over the posterior border 
of this muscle. Each side of the pharynx presents two muscle plaques 
(c, f) attached to the ventral margins of the upper half of the oblique 
ridge, but extending posteriorly to the oesophagus. The posterior 
dorsal wall of the pharynx is covered with several longitudinal mus- 
cles, the most prominent of which is a wide, median, external band 
of fibrils {g) deflected from the posterior part of the broad anterior 
transverse muscle (c) . Concealed by this muscle are two longitudinals 
of a deeper set, arising anteriorly on the buccal region beneath the 
first transverse muscle (a) and extending posteriorly to the anterior 
end of the oesophagus. Several superficial longitudinal fibers lie more 
laterally. 

The buccal region of the stomodeum is thus distinguished by its 
strong circular musculature, which evidently gives it a powerful 
constrictor action. The pharynx is provided principally with longi- 
tudinal muscles, and its action, except for that produced by the an- 
terior dorsal transverse muscle, must be one of lengthwise contrac- 
tion. 

The entire length of the oesophageal tube is sheathed in a close 
series of strong circular fibers {i) which are complete rings, except 
a few of the most posterior interrupted dorsally at the anterior end of 
the crop. 

The inner walls of the pharynx and oesophagus form four longi- 
tudinal folds — one dorsal, one ventral, and two lateral. The dorsal 
fold is broad, flat, and straight-edged. It arises at the base of the 
labrum, where its margins begin at the tormae, and continues to the 
posterior end of the oesophagus, where it is lost with the sudden 
widening of the stomodeal tube in the crop. Between the pharynx and 
the oesophagus, the continuity of the dorsal fold is interrupted by a 
transverse fold. The ventral and lateral folds are less definite, rounded 



I 



NO. 3 INSECT HEAD SNODGRASS I47 

inflections of the stomodeal wall, continuous from the pharynx into 
the oesophagus. In Lycophotia margaritosa each of these folds ends 
at the opening of the crop in a prominent fleshy papilla covered with 
small chitinous points. Between the folds are four deep channels ex- 
tending from the mouth to the crop, two dorso-lateral, and two latero- 
ventral. Possibly it is through these channels that the alimentary 
liquid, which caterpillars frequently eject from the mouth when 
irritated, is conveyed forward from the crop. 

The muscles of the crop (fig. 55, Cr) are arranged longitudinally 
and circularly. The circular muscles (/), except for a few closely 
placed anterior bands (k), are widely spaced, external circular fibers. 
They all completely surround the crop like the hoops of a barrel. At 
the junction of the crop with the oesophagus, there are several short 
transverse fibers (/) confined to the dorsal surface. All the muscles 
of the crop are strongly fibrillated (fig. 56 A, B, C, D). The circular 
bands have distinct nuclei, but nuclei were not observed in the longi- 
tudinal muscles of noctuid species examined. 

The longitudinal muscles of the crop (fig. 55, vi) have their origin 
in single fibrillae (fig. 56 A) or small bundles of fibrillae (B) given 
off from the posterior margins of the circular fibers. They are, there- 
fore, of the nature of branches of the circular fibers, and this fact 
may account for their lack of nuclei. Moreover, the longitudinal 
muscles are not continuous, individual bands, but are everywhere 
branched and intimately united by intercrossing bundles of fibrillae in 
such a manner that the entire layer becomes a plexus of muscle tissue 
(fig. 56 C) . Most of the fibrillae of this layer spring from the anterior 
circular fibers, but probably all the circular fibers contribute at least 
a few elements to the longitudinal plexus. On the anterior end of the 
crop, the longitudinal fibrillae appear as simple connectives between 
the transverse fibers (fig. 55, /). On the posterior end of the crop 
(fig. 56 F), the longitudinal muscles again break up into smaller fibril 
bundles, and at last into fine strands that reunite with the external 
circular fibers of the crop or the proventriculus. 

The proventricular region (fig. 56 F, Pvcnt) resembles the oesoph- 
agus in being surrounded by a close series of strong circular muscle 
fibers (w). There is no distinct inner muscular sheath here, but the 
circular fibers are all connected by small bundles of fibrillae going from 
one to another (G), some to the first neighboring fibers, others to 
the second, third, or fourth removed in either direction. The proven- 
triculus has a special feature in the presence of an external layer of 
fine, widely-spaced, longitudinal muscles, stretched freely between its 
two ends (fig. 56 F, o). These threadlike strands arise anteriorly 



148 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 81 

from branches that spring from the posterior ends of the longitudinal 
crop muscles, and from the anterior circular fibers of the proventric- 
ulus. Posteriorly they again break up into branches that are lost in 
a plexus of fibers at the junction of the proventriculus with the ven- 
triculus (Vent). 

A study of the stomodeal muscle sheath of the caterpillar thus 
shows that the usual brief statement that the insect stomodeum is 
surrounded by an external layer of circular fibers and an internal layer 
of longitudinal fibers must be considerably modified and amplified to 
fit conditions in the caterpillar. The proctodeal muscles of the cater- 
pillar are even more complicated than are those of the stomodeum. 
The high degree of development in the alimentary musculature of the 
caterpillars accords with the general specialization of the caterpillar 
as an animal most efficient in feeding, and the extreme development 
of the somatic musculature is only another adaptation to the same end. 

The dilator muscles of the stomodeum are inserted dorsally and 
ventrally on the stomodeal walls. The dorsal muscles are grouped into 
three sets corresponding with the buccal, pharyngeal, and oesophageal 
regions of the stomodeum. The dilator muscles of the dorsal and 
cent;:al series, enumerated according to the order of their insertions, 
are as follows : 

20. — First dorsal dilators of the buccal cavity (fig. 55). — A pair 
of slender muscles arising on submarginal ridge of clypeus (fig. 50 
I, h) ; extending posteriorly to insertions laterally on roof of mouth 
cavity just before first band of circular stomodeal muscles. 

21. — Second dorsal dilators of the buccal cavity (fig. 55). — Origins 
on clypeus, above middle and close to lateral margins ; insertions 
medially on dorsal wall of mouth cavity between insertions of 20. 

22, 2^. — Third and fourth dorsal dilators of the buccal cavity (fig. 
55). — Two pairs of slender muscles: those of each side arising to- 
gether in ventral angles of clypeal triangle just above ends of sub- 
marginal ridge ; inserted dorso-laterally on buccal region, 22 before 
second band of transverse muscles (b), <?j behind it. 

A wide space occupied by the third transverse muscle band (c) 
intervenes between the dilators of the buccal region and those of the 
true pharyngeal region. 

24. — First dorsal dilators of the pharynx (fig. 55). — Origin on 
upper part of clypeus just internal to epistomal ridge; insertion 
medially on dorsal wall of pharynx laterad of frontal ganglion. These 
are clearly true pharyngeal muscles ; their points of origin have evi- 
dently crossed the epistomal ridges to the clypeus. 



r 



NO. 3 



INSECT HEAD — SNODGRASS 



149 




r-; [ 'j~>-^r'/V- 

mm 

m^ A 



Blli 



m 



^mmM 1: 



B 



m 



lllllll'H 



iiiilifii 



E 




c 



,.»;V^fr'?S'(?''i^'«-j 



Cr 



^^: 



.c 







Pvent lilit^gEl^-- 
vent ;U§f lip f,^ p 



^' '-• -mi J f l^ 1 ^f 

Fig. 56. — Muscles of the stomodeum of a noctuid caterpillar. 

A, B, origin of longitudinal muscles (in), of crop (see fig. 55) from fibrils 
deflected from the anterior circular muscles (/, k). C, plexus of longitudinal 
muscles, anterior part of crop. D, piece of circular fiber from anterior part 
of crop. E, a connecting fiber between circular and longitudinal muscles. F, 
posterior end of crop (Cr), proventriculus (Pvcnt), and anterior end of ven- 
triculus (Vent): I, m, circular and longitudinal muscles of crop; n, circular 
muscles of proventriculus ; o, external longitudinal fibers of proventriculus ; p, 
first suspensory muscles of ventriculus. G, parts of seven consecutive circular 
fibers of proventriculus, showing bundles of uniting fibrils, external. 



150 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 81 

^5. — Second dorsal dilators of the pharynx (fig. 55). — Origins on 
epistomal ridges near union with frontal ridge ; insertions dorso- 
laterally on pharynx. 

26. — Third dorsal dilators of the pharynx ( fig. 55) . — Each arises on 
cranial wall laterad of origins of antennal muscles ; extends medially, 
posteriorly, and downward to insertion on pharynx just laterad of 2-,. 

The insertions of muscles 24, 2§, and 26 all lie posterior to the 
frontal ganglion connective. 

2/. — Fourth dorsal dilators of the pharynx (fig. 55). — A group of 
fibers on each side, arising on outer surface of lower end of frontal 
ridge ; converging to one or two stalks inserted on dorsal wall of 
pharynx just before brain. 

The following dorsal muscles are inserted behind the brain and on 
the region of the stomodeum that may be distinguished in the cater- 
pillar as the oesophagus, but which is the so-called posterior pharynx 
in Orthoptera. 

28, 2p, 50. — Dorsal dilators of the oesophagus (fig. 55). — Three 
fans of muscles arising on posterior margin of cranial walls on each 
side of vertical emargination ; the spreading fibers inserted dorso- 
laterally on oesophagus from brain to crop. 

J/. — First ventral dilators of the pJuirynx (fig. 55). — A pair of 
long slender muscles arising on transverse bar of tentorium (fig. 53 
D, Tnt), converging to ventral wall of pharynx where inserted just 
behind first ventral transverse muscle {d) . 

^2, 55. — Second and third ventral dilators of the pharynx (fig. 55). 
— A pair of small muscles on each side arising on extreme outer ends 
of transverse tentorial bar ; fibers spreading at insertion ventro-later- 
ally on pharynx just before anterior circular muscles of oesophagus. 

34' 35> 3^- — Ventral dilators of the oesophagus (fig. 55). — Three 
large fans of fibers arising on postoccipital apodemes on each side 
laterad of posterior roots of tentorium ; the spreading fibers inserted 
ventro-laterally on oesophagus from circum-oesophageal nerve con- 
nective to crop. 

THE MUSCULATURE OF BACK OF HEAD, AND NATURE 
OF THE INSECT NECK 

The head of the caterpillar is remarkably mobile. It is provided 
with a wonderful system of muscles, the fibers of which arise mostly 
in the prothorax and are distributed at their insertions upon the post- 
occipital ridge of the head in such a manner as to enable the caterpillar 
to make all possible head movements of which it conceivably might 
have need (fig. 57 A, B, C). 



NO. 3 



INSECT HEAD SNODGRASS 



151 



The muscles of the prothorax of the American tent caterpillar, 
Malacosoma americana, are illustrated in figure 57. At A are shown 
the lateral and ventral muscles as seen from a posterior dorsal view, 
with the head turned somewhat downward on the neck ; B shows the 
dorsal muscles as seen from below; C presents an inner view of all 






Fig. 57. — Muscles of the prothorax of a caterpillar, Malacosoma americana. 

A, prothoracic muscles inserted on lateral and ventral parts of back of head, 
and ventral muscles of mesothorax, posterior view. B, dorsal muscles of pro- 
thorax and mesothorax inserted on dorsal half of back of head, seen from 
below. C, innermost layers of muscles of right half of prothorax, internal 
view. D, external muscles of right half of prothorax. 

Isg, intersegmental fold ; Li, base of prothoracic leg ; PoR, postoccipital 
ridge of head ; s, edge of tergal plate of prothorax ; iSp, first spiracle ; Tnt, 
transverse bar of tentorium ; vap, ventral apodemal plate of postoccipital 
ridge. 



the muscles in the right half of the prothorax inserted on the head ; 
and D gives the muscles of the same side that lie external to those 
shown in C, except the single fiber arising just dorsal to the spiracle, 
which is shown in both figures. 



152 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 81 

The various fibers of the head muscles are mostly arranged in 
groups, and it is easiest to trace them from their points of insertion 
on the back of the head. Inserted in the median notch of the vertex 
there is a dorsalmost group of long fibers that diverge posteriorly to 
the dorsal wall of the prothorax (B, C), the middle fibers of each 
group going to the posterior margin of the segment. External to 
these muscles, a group of short fibers, inserted serially on each side, 
extends posteriorly and dorsally to the tergal plate of the prothorax. 
Laterally there are inserted on the postoccipital ridge several fibers 
that spread to their origins on the tergal plate, and a group of four 
long fibers going dorsally and medially to the intersegmental fold 
(Isg), with the two median fibers crossing the latter to the dorsum of 
the mesothorax. Three lateral groups of fibers ( A, C) go ventrally and 
posteriorly from their head insertions, one to the sternal interseg- 
mental fold, another to the region just before the base of the protho- 
racic leg, and the third to the median longitudinal fold between the 
legs. Ventrally there are inserted on the ventral apodeme of the 
hypostomal region (C, z'ap) the anterior ends of the ventral longitudi- 
nal muscles of the prothorax (A, C), and a group of four long fibers 
on each side that arise on the region above the spiracle. 

It is of particular interest to observe that, in the caterpillar, the 
ventral longitudinal muscles of the prothorax are not inserted on the 
tentorium (fig. 57 A, C) as they are in orthopteroid insects, and fur- 
thermore, that all the principal longitudinal ventral muscles of the 
thorax have their origin on the intersegmental folds, and not on in- 
trasegmental apophyses. The primitive anterior insertion of these 
muscles in the prothorax, therefore, should be on a ventral interseg- 
mental fold between the prothorax and the last head segment. We 
have already seen that there is evidence of the loss of the true labio- 
prothoracic intersegmental fold, since the postoccipital ridge, which 
bears the anterior attachments of the prothoracic muscles in all known 
insects, appears to be the fold between the maxillary and the labial 
segments. If so, the original attachments have been lost and the 
muscles now extend through the length of two primary segments. 

Furthermore, the attachment of the ventral muscles of the cater- 
pillar on the hypostomal regions of the head must signify a migration 
of the muscles from their primitive sternal insertions, for the hypo- 
stomal lobes clearly belong to the postgenae, and are, therefore, ventral 
extensions of the tergal area of the head wall. In any case, an attach- 
ment of the ventral muscles on the bridge of the tentorium certainly 
represents a farther displacement of the muscle insertions by a final 



I 



NO. 3 



INSECT HEAD SNODGRASS 



153 



migration from the tergal postoccipital ridge to the posterior ten- 
torial apophyses. 

The question of the morphology of the cervical region of the insect 
must yet remain a puzzle ; but the musculature gives no evidence of the 
existence of a neck segment. On the other hand, the fold in the 
integument of the caterpillar between the neck (fig. 57 D, Cv) and 
the prothoracic tergum {To) is suggestive of being the true interseg- 
mental line between the labial segment and the prothoracic segment, 
and several muscles of the prothorax have their anterior attachments 
upon it (D). If the primitive insect is conceived as a continuously 
segmented, vermiform animal, the neck, or any other secondary inter- 
segmental area, must be a part of a primary segmental region. From 
the evidence at hand it seems more probable that the region of the 
insect neck belongs to the labial segment, than to an anterior part 
of the prothoracic segment. 



ABBREVIATIONS USED ON THE FIGURES 



Ab, abdomen. 

abplp, abductor of palpus. 

adplp, adductor of palpus. 

Am, amnion. 

AMR, anterior mesenteron rudiment. 

An, anus. 

Ant, antenna. 

AntNv, antennal nerve. 

Ao, aorta. 

AP, apical plate. 

AR, antennal ridge. 

Arc, archicerebrum. 

as, antennal suture. 

AT, anterior arm of tentorium. 

at, anterior tentorial pit. 

BC, body cavity. 
Bdy, body. 
Blc, blastocoele. 
Bid, blastoderm. 
Bp, blastopore. 
iBr, protocerebrum. 
2Br, deutocerebrum. 
SBr, tritocerebrum. 
Bs, basisternum. 
BxiC, buccal cavity. 

CA, corpus allatum. 
Cd, cardo. 
Cer, cercus. 



Ch, chelicera. 

Cho, chorion. 

Clp, clypeus. 

CoeCon, circumoesophageal connective. 

Com, commissure. 

SConi, commissure of tritocerebral 

lobes. 
Con, connective. 
cs, coronal suture. 
ct, coxo-trochanteral joint. 
Cth, cephalothorax. 
Cv, neck, cervix. 
cv, cervical sclerite. 
Cx, coxa. 

dap, dorsal apodemal plate of postoc- 
cipital ridge. 

DMcl, dorsal longitudinal body muscle. 

DNv, dorsal longitudinal nerve. 

DT, dorsal arm of tentorium. 

dt, attachment of dorsal tentorial arm 
to wall of cranium. 

E, compound eye. 
Ecd, ectoderm. 
End, endoderm. 
Endp, endopodite. 

Ephy, epipharynx, epipharyngeal sur- 
face. 
Eps, episternum. 



154 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 



ER, epistomal ridge. 
es, epistomal suture. 
Exp, exopodite. 



KLt, ventral adductors arising on ten- 
torium, or hypopharyngeal apo- 
demes. 



F, femur. 

fga, flexor of galea. 

Fl, flagellum. 

ftc, flexor of lacinia. 

flee, cranial flexor of lacinia. 

fles, stipital flexor of lacinia. 

For, foramen magnum, or " occipital " 

foramen. 
Fr, frons. 
/;-, " adfrontal " 
FrGng, frontal ganglion. 
fs, frontal suture. 
ft, femoro-tibial joint. 

Ga, galea. 

GC, gastric caecum. 

Gc, gastrocoele, archenteron. 

Gch, gnathochilarium. 

Ge, gena. 

Gl, glossa. 

Gn, gnathal segments. 

Gnc, gnathocephalon. 

Gng, ganglion. 

Gil, gula. 

H. head. 

Hphy, hypopharynx. 

Hst, hypostoma. 

/, tergal promoter muscle of an appen- 
dage. 
I -VI, segments of the head. 
Isg, intersegmental fold. 

/, tergal remoter muscle of an appen- 
dage. 

K, sternal promotor muscle of an ap- 
pendage. 

KL, ventral adductor muscles. 

KLh, ventral adductors arising on hy- 
popharynx. 

KLk, ventral adductors united by liga- 
ment {k) forming "dumb-bell 
muscle." 



L, leg. iL, first leg. L^, prothoracic 
leg. 
sternal remoter muscle of an appen- 
dage. 

LB. primitive limb base (coxa and 
subcoxa). 

Lb, labium. 

LbNv, labial nerve. 

Ibmcl, labial muscles. 

Lc, lacinia. 

Lni, labrum. 

LNv, lateral stomodeal nerve. 

Md, mabdible. 
MdC, mandible cavity. 
MdNv, mandibular nerve. 
Ment, mesenteron. 
Mps, mouth parts. 
Msb, primary mesoblast. 
Mse, mesenchyme. 
Msd, mesoderm. 
Mst, metastomium. 
Mt, mentum. 
Mth, mouth. 
Mx, maxilla. 
iMx, first maxilla. 
2Mx, second maxilla. 
MxC, maxilla cavity. 
MxNv, maxillary nerve. 

NC, nerve cord. 
NMb, neck membrane. 
NpJi, nephridium. 

O, ocellus. 

levator muscle of palpus, or of tro- 
chanter. 
Oc, occiput. 
OcR, occipital ridge. 
ocs, occipital suture. 
OE, oesophagus. 

OcGng, oesophageal, or posterior me- 
dian stomodeal ganglion. 
OpL, optic lobe. 
OR, ocular ridge. 
OS, ocular suture. 



NO. 3 



INSECT HEAD — SNODGRASS 



155 



P, thoracic depressor muscle of tro- 
chanter. 

PcR, posterior cranial ridge. 

Pdc, pedicel. 

Pdp, pedipalp. 

Pge, postgena. 

Pgl, paraglossa. 

Ph, phragma. 

Phy, pharynx. 

PLGng, posterior lateral stomodeal 
ganglion. 

Pip, palpus 

Pnt, postantennal appendage. 

Poc, postocciput, postoccipital rim of 
foramen magnum. 

PoR, postoccipital ridge. 

pos, postoccipital suture. 

Pp, " pleuropodium," specialized ap- 
pendage of first abdominal seg- 
ment. 

Ppd, parapodium. 

Ppt, periproct. 

PrC, preoral cavity. 

Pre, protocephalon. 

Priit, preantennal appendage. 

Proc, proctodeum. 

Prst, peristomium. 

Prtp, protopodite. 

Pst, prostomium. 

PT, posterior arm of tentorium. 

pt, posterior tentorial pit. 

Ptar, praetarsus. 

Q, depressor muscle of palpus, or of 

trochanter. 
Rd, posterior fold of tergum. 

rh, retractor of hypopharynx. 
RNz>, recurrent nerve. 



SA, sternal apophysis. 
Sep, scape. 
Sex, subcoxa. 
Ser, serosa. 
Set, seta, setae. 
SgR, subgenal ridge. 
sgs, subgenal suture. 
SID, salivary duct, silk gland duct. 
SJO, opening of salivary duct. 
Sint, submentum. 

SeoGng, suboesophageal ganglion. 
Sp, spiracle, iSp, first thoracic spir- 
acle. 
Spn, spina. 
Spt, spinneret. 
St, stipes. 
Stoni, stomodeum. 

T, tergum. 

depressor muscle of tibia. 
Tar, tarsus. 
Tb, tibia. 
Th, thorax. 
77, tentacle. 
Tip, telopodite. 
Tnt, tentorium. 
Tor, torma. 
Tr, trochanter. 

J\ fifth head segment. 

vap, ventral apodemal plate of postoc- 
cipital ridge. 

VI, sixth head segment. 

VMcI, ventral longitudinal body mus- 
cle. 

VNC, ventral nerve cord. 

VNv, ventral longitudinal nerve. 

Vx, vertex. 



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SMITHSONIAN MISCELLANEOUS COLLECTIONS 

VOLUME 81. NUMBER 4 



DRAWING BY 

JACQUES LEMOYNE DE MORGUES OF 

SATURIOUA, A TIMUCUA CHIEF 

IN FLORIDA, 1564 

(With One Plate) 

BY 
DAVID I. BUSHNELL, Jr 



(Publication '2972) 



CITY OF WASHINGTON 

PUBLISHED BY THE SMITHSONIAN INSTITUTION 

AUGUST 23, 1928 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOLUME 81, NUMBER 4 



DRAWING BY 

JACQUES LEMOYNE DE MORGUES OF 

SATURIOUA, A TIMUCUA CHIEF 

IN FLORIDA, 1564 



(With One Plate) 



BY 

DAVID I. BUSHNELL, Jr 



(Publication 2972) 



CITY OF WASHINGTON 

PUBLISHED BY THE SMITHSONIAN INSTITUTION 

AUGUST 23, 1928 






Z'tii Boxi> QBattimorc (prcee 

BALTIMORE, MD., U. S. A. 



DRAWING BY JACQUES LEMOYNE DE MORGUES OF 

SATURIOUA, A TIMUCUA CHIEF IN 

FLORIDA, 1564 

By DAVID I. BUSHNELL, JR. 
(With One Plate) 

When it became known in Europe that a new continent had been 
discovered beyond the sea, that the lands reached by CoUimbus and 
his companions did not form part of Asia but were a new and 
distinct region, wonder was aroused as to the sort of people who 
were to be found in the strange and unknown country. So great was 
the interest thus manifested that many narratives of early voyages 
contain accounts of the natives encountered along the coasts and some 
refer, all too briefly, to the manners and customs of the Indians, a 
term erroneously applied to the inhabitants of the New World. Many 
records are preserved of natives having been taken to Europe by the 
explorers. It is written that when the Cabots — first to reach the con- 
tinent of North America — returned to England in the year 1497, they 
carried three of the strange people from the newly discovered lands, 
and that four years later Cortereal compelled others to return with 
him to Europe. Likewise when Jacques Cartier reached France in 
1535, after exploring the great River St. Lawrence, he had on board 
his small vessel a native chief taken in the wilderness. This tends 
to prove that many were eager to learn about the people who lived 
in the mysterious region far to the westward, beyond the sea. With 
this evidence of interest in the people of the New World it is difficult 
to believe that pictures were not made of them ; sketches or paintings 
to portray their peculiar customs, strange ornaments and dress, and 
frail habitations. But no drawings are known to have been made dur- 
ing the voyages of the Cabots, of Ponce de Leon, Varrazano, Narvaez, 
de Soto, or Cartier. No proof that any pictures of Indians of North 
America were made during the first half of the sixteenth century has 
been discovered. And although the account of the voyages of Cartier, 
as presented by Ramusio, is accompanied by several crude illustra- 
tions, there is no evidence to indicate that the drawings were made by 
a person who had visited Canada. Thus it would appear that not until 
the year 1564, when the French expedition led by Laudonniere set 

Smithsonian Miscellaneous Collections, Vol. 81, No 4 



2 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. Ol 

sail from Havre de Grace for the Land of Florida, did an artist 
accompany an expedition for the definite purpose of making drawings 
to be taken back to Europe. Consequently Jacques Lenioyne de 
Morgues, artist, who accompanied Laudonniere, made the earliest 
known pictures of Indians of North America. Many sketches were 
undoubtedly made by the artist during the eventful year he remained 
in Florida but only one original example of his work can now be 
traced, this being a drawing of the great chief Saturioua who claimed 
the land on which the French erected Fort Carolina. 

JACQUES LEMOYNE DE AIORGUES 

Very little is known of the life and career of the artist who ac- 
companied Laudonniere to Florida. He appears to have been a man 
of culture and learning. He was a Huguenot and seems to have been 
known personally by Charles IX. He prepared a brief Narrative of 
events in Florida which was printed by Theodoro de Bry, in the year 
1 59 1, as the second part of Grand Voyages. Together with this text 
were the engraved reproductions of 42 drawings made by Lemoyne 
revealing scenes in Florida, the natives, their habitations, and events 
of interest.^ To quote from the English translation of Lemoyne : 

" Charles IX, King of France, having been notified by the Admiral 
de Chatillon that there was too much delay in sending forward the 
re-enforcements needed by the small body of French whom Jean 
Riband had left to maintain the French dominion in Florida, gave 
orders to the admiral to fit out such a fleet as was required for the 
purpose. The admiral, in the mean while, recommended to the king a 
nobleman of the name of Renaud de Laudonniere ; a person well 
known at court, and of varied abilities, though experienced not so 
much in military as in naval afifairs. The king accordingly appointed 
him his own lieutenant, and appropriated for the expedition the sum 
of a hundred thousand francs." The Narrative continues : " I also 
received orders to join the expedition, and to report to M. de Laudon- 
niere .... I asked for some positive statements of his own views, 
and of the particular object which the king desired to obtain in coni- 



^ Two works have been quoted in preparing these notes : 

a. History of the First Attempt of the French to Colonize the Newly 
Discovered Country of Florida. By Rene Laudonniere. In His- 
torical Collections of Louisiana and Florida. By B. F. French. New 
York, 1869. 

h. Narrative of Le Moyne, an Artist who accompanied the French 
Expedition to Florida under Laudonniere, 1564. Translated from 
the Latin of De Bry. Boston, 1875. 



NO. 4 JACQUES LEMOYNE DE MORGUES BUSH NELL 5 

manding my services. Upon this he promised that no services except 
honorable ones should l)e required of me ; and he informed me that 
my special duty, when we should reach the Indies, would be to map the 
seacoast, and lay down the position of towns, the depth and course of 
rivers, and the harbors ; and to represent also the dwellings of the 
natives, and whatever in the province might seem worthy of observa- 
tion : all of which I performed to the best of my ability, as I showed 
his majesty, w^hen, after having escaped from the remarkable perfidies 
and atrocious cruelties of the Spaniards, I returned to France." 

The three vessels of the expedition sailed from Havre de Grace 
April 20, 1564. Their first stop was at the Canaries, thence they 
sailed to the West Indies. x\t one island, " called Dominica, we 
watered. Making sail again, we reached the coast of Florida, or 
New France as it is called, on Thursday, June 22'' They had arrived 
ofif the mouth of the River of May, the present St. Johns. Soon 
ascending the stream a few miles they selected a site where Fort 
Carolina was erected. 

Lemoyne was in Fort Carolina September 20, 1565. when it was 
attacked and taken by the Spaniards. He fled and wandered through 
the swamps several days before meeting Laudonniere and some fifteen 
others who had escaped the massacre. Later they reached the mouth 
of the river, boarded one of the small ships and made sail for France, 
" ill manned and ill provisioned. But God, however, gave us so 
fortunate a voyage, although attended with a good deal of sufi^ering, 
that we made the land in that arm of the sea bordering on England 
which is called St. George's Channel." 

Now to quote from Laudonniere's record. 

The first of the three ships to return to France departed from 
Florida July 28, 1564. About November 10, 1564 " Captain Bourdet 
determined to leave me, and to return to France." During the summer 
of 1565 the French were visited by the English Admiral Hawkins. 

Laudonniere. with his small party including the artist Lemoyne, 
sailed from Florida September 25, 1565. " About the 25th of Octol)er, 
in the morning, at the break of day, we described the Isle of Flores, 
and one of the Azores, where, immediately upon our approaching to 
the land, we had a mighty gust of wind, which came from the north- 
east, which caused us to bear against it four days ; afterwards, the 
wind came south and south-east, and was always variable. In all the 
time of our passage, we had none other food saving biscuit and water." 
About November 10, 1565, they reached the coast of Wales and 
landed, having been carried out of their course and thus failed to 
reach France. They had landed at Swansea. Laudonniere then wrote : 



4 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

" For mine own part I purposed, with my men. to pass by land ; and, 
after I had taken leave of my mariners, I departed from Szvaiisca, 
and came, that night, with my company, to a place called Morgan, 
where the lord of the place, understanding what I was, staid me with 
him for the space of six or seven days ; and, at my departure, moved 
with pity to see me go on foot, especially being so weak as I was, gave 
me a little hackney. 

" Thus I passed on my journey — first to Bristol, and then to 
London, where I went to do my duty to M. de Foix, which, for the 
present, was the King's ambassador, and helped me with money in m}' 
necessity. From thence I passed to Calais, afterward to Paris, where 
I was informed that the king was gone to Monlins, to sojourn there ; 
incontinently, and with all the haste I could possibly make, I got me 
thither, with part of my company." 

Lemoyne was probably one of the company, and it may have been 
at this time that he revealed to the king the work he had done in 
Florida. 

How long Lemoyne continued to live in France is not known but 
later he crossed the channel and resided in London. He was a Hugue- 
not and for that reason may have sought safety in flight. During 1587 
Lemoyne was in London, in the service of Sir Walter Raleigh, when 
he was visited by De Bry in the endeavor to purchase his papers relat- 
ing to the expedition to Florida, but as has been written : " Lemoyne 
resisted all persuasions to part with his papers. After Lemoyne's 
death De Bry bought them of his widow (1588), and published them 
in 1591." 

What became of Lemoyne's drawings is not known. Possibly those 
secured by De Bry were taken to Frankfort and there copied by the 
engravers, later to be lost or scattered. No example of the artist's 
work is in the British Museum, London; the Louvre, Paris; or the 
Galleria degli Uffizi, Florence. 

It may be suggested that Lemoyne's connection with Sir Walter 
Raleigh influenced the latter in sending the English artist John White 
to Virginia, in 1585. White's instructions were quite similar to those 
received by Lemoyne some twenty years before. Their work was of 
the same nature. 

SATURIOUA RE DELLA ELORIDA 

Saturioua was a Timucua chief whose tribe claimed and occupied 
territory on both sides of the St. John River, from its mouth inland 
for some distance as well as up and down the coast. 



NO. 4 JACQUES LEMOYNE DE MORGUES BUSH NELL 5 

During the summer of 1564, while Fort Carolina was being con- 
structed by Laudonniere, " several chiefs visited our commander, and 
signified to him that they were under the authority of a certain king 
named Saturioua, within the limit of whose dominions we were, whose 
dwelling was near us. and who could muster a force of some thou- 
sands of men." 

Saturioua soon desired to see the work being done by the French 
and visited the site chosen for the fort. " He sent forward, however, 
some two hours in advance of his own appearance, an officer with a 
company of a hundred and twenty able-bodied men, armed with bows, 
arrows, clubs, and darts, and adorned, after the Indian manner, with 
their riches ; such as feathers of different kinds, necklaces of a select 
sort of shells, bracelets of fishes' teeth, girdles of silver-colored balls, 
some round and some oblong; and having many pearls fastened on 
their legs. Many of them had also hanging to their legs round flat 
plates of gold, silver, or brass, so that in walking they tinkled like 
little bells. This officer, having made his announcement, proceeded to 
cause shelter to be erected on a small height near by of branches 
of palms, laurels, mastics, and other odoriferous trees, for the accom- 
modation of the king." And soon the great chief arrived, " accom- 
panied by seven or eight hundred men, handsome, strong, well-made, 
and active fellows, the best-trained and swiftest of his force, all under 
arms as if on a military expedition." The meeting proved one of great 
interest to both French and Indian. Laudonniere made known to 
Saturioua that he had been " sent by a most powerful king, called 
the King of France, to offer a treaty by which he should become a 
friend to the king here, and to his allies, and an enemy to their 
enemies ; an announcement which the chief received with much plea- 
sure. Gifts were then exchanged in pledge of perpetual friendship 
and alliance." The Indians soon departed, but the French hastened 
with greater energy the completion of the fort. 

Some days passed and the time arrived when Saturioua desired to 
test the sincerity of the French. " The chief sent messengers to 
M. de Laudonniere, not only to confirm the league which had been 
made, but also to procure the performance of its conditions, namely, 
that the latter was to be the friend of the king's friends, and the enemy 
of his enemies ; as he was now organizing an expedition against 
them." A vague, ambiguous reply was received by the messengers and 
by them carried to Saturioua. The great chief then visited the fort, 
accompanied by a large number of men. He attempted to have the 
French go with him on his expedition against his enemies farther up 
the river but they declined. " Failing, however, to obtain what he 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOL. 8l 



wished, he set out on his expedition with his own men. While these 
aftairs were in progress, M. de Laudonniere sent his second ship, com- 
manded by Pierre Capitaine, to France." 

Saturioua, surrounded by his chiefs and warriors, preparing to 
start on the expedition, was the subject of a drawing by Lemoyne, 
one engraved by De Rry, Ijut the descrii)tion of the picture as given by 
the artist is really more complete than the reference just quoted. 

The description of the engraving, given by De Bry. was evidently 
prepared by Lemoyne himself. The English translation is now quoted : 




I'H.. I. — Ceremonies performed by Saturioua before going on an ex])editinn 
against the enemy. From De Bry, 1591. 



" It is mentioned in the account of the second voyage that the French 
made a treaty of friendship with a powerful chief of the vicinity, 
named Saturioua, with agreement that they were to erect a fort in his 
territory, and were to be friends to his friends, and enemies to his 
enemies; and. further, that on occasion they should furnish him some 
arquebusiers. About three months afterwards, he sent messengers to 
Laudonniere to ask for the arquebusiers according to the treaty, as he 
was about to make war upon his enemies. Laudonniere, however, sent 
to him Capt. La Caille with some men, to inform him courteously that 
he could not just then supply any soldiers, for the reason that he hoped 



NO. 4 JACQUES LEMOYNE DE MORGUES BUSHNELL 7 

to be able to make peace between the parties. But the chief was in- 
dignant at this reply, as he could not now put off his expedition, having 
got his provisions ready, and summoned the neighboring chiefs to his 
aid ; and he therefore prepared to set out at once. He assembled his 
men, decorated, after the Indian manner, with feathers and other 
things, in a level place, the soldiers of Laudonniere being present ; and 
the force sat down in a circle, the chief being in the middle. A fire was 
then lighted on his left, and two great vessels full of water set on his 
right. Then the chief, after rolling his eyes as if excited by anger, 
uttering some sounds deep down in his throat, and making various ges- 
tures, all at once raised a horrid yell ; and all his soldiers repeated this 
yell, striking their hips, and rattling their weapons. Then the chief, 
taking a wooden platter of water, turned toward the sun, and wor- 
shipped it ; praying to it for a victory over the enemy, and that, as 
he should now scatter the water that he had dipped up in the wooden 
platter, so might their blood be poured out. Then he flung the water 
with a great cast up into the air ; and, as it fell down upon his men, 
he added, ' As I have done with this water, so I pray that you may 
do with the blood of your enemies.' Then he poured the water in the 
other vase upon the fire, and said, ' So may you be able to extinguish 
your enemies, and bring back their scalps.' Then they all arose, and 
set off by land up the river, upon their expedition." 

Laudonniere wrote regarding these happenings : " About two 
months after our arrival in Florida, the Paraconssy Saturioua sent 
certain Indians unto me to know whether I would stand to my promise, 
which I had made him at my first arrival in that country : which was, 
that I would show myself friend to his friends, and enemy unto his 
enemies ; and, also, to accompany him with a good number of harque- 
buses, when he should see it expedient, and should find a fit occasion 
to go to war." Laudonniere declined to join his forces with those of 
Saturioua and the latter departed on the war-like expedition without 
the promised aid of the French. Laudonniere then continued his nar- 
rative : " The ceremony which this savage used, before he embarked 
his army, deserveth not to be forgotten ; for, when he was sitting down 
by the river's side, being compassed about with ten other paracoussics, 
he commanded water to be brought him speedily. This done, looking 
up into heaven, he fell to discourse of divers things, with gestures that 
showed him to be in exceeding great choler, which made him one while 
shake his head hither and thither ; and, by and by, with, I wot not what 
fury, to turn his face towards the country of his enemies, and to 
threaten to kill them. He oftentimes looked upon the sun, praying 
him to grant him a glorious victory of his enemies ; which, when he 



8 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

had done, by the space of half an hour, he sprinkled, with his hand, a 
little of the water, which he held in a vessel, upon the heads of the 
paracoussies, and cast the rest, as it were, in a rage and despite, into a 
fire, which was there prepared for the purpose. This done, he cried 
out, thrice, He Tliiiiiogoa! and was followed with five hundred In- 
dians, at the least, which were there assembled, which cried, all with 
one voice. He TJiUnogoa! " 

These events transpired during the latter part of August, 1564. 

SATURIOUA— DRAWING BY LEMOYNE 

The original drawing now reproduced for the first time, is in 
crayon — black and sanguine. It bears a legend in Italian which reads : 
Saturiona Re della Florida ncW America Settertionale in atto di 
andarc alia Gtierra. Translated it is : " Saturioua King of Florida in 
North America in the act of going to war." This evidently shows the 
chief immediately after the completion of the ceremony mentioned on 
preceding pages. He has grasped his spear but continues to hold the 
wooden bowl containing water. 

Details are revealed in the drawing with great clearness. Several 
of these may be explained by quoting from Lemoyne's notes attached 
to various sketches reproduced by De Bry. Describing the peculiar 
ear ornament represented as being worn by Saturioua, Lemoyne wrote : 
" All the men and women have the ends of their ears pierced, and pass 
through them small oblong fish-bladders, which when inflated shine 
like pearls, and which, being dyed red, look like a light-colored car- 
buncle." Tattooing was practiced extensively and " all these chiefs 
and their wives ornament their skins with punctures arranged so as to 

make certain designs Doing this sometimes makes them sick 

for seven or eight days. They rub the punctured places with a certain 
herb, which leaves an indelible color." But the strangest of their 
customs, " For the sake of further ornament and magnificence, they 
let the nails of their fingers and toes grow, scraping them down at 
the sides with a certain shell, so that they are left very sharp. They 
are also in the habit of painting the skin around their mouths of a blue 
color." Elsewhere Lemoyne wrote: " They let their nails grow long 
both on fingers and toes, cutting the former away, however, at the 
sides, so as to leave them very sharp, the men especially ; and, when 
they take one of the enemy, they sink their nails deep in his forehead, 
and tear down the skin, so as to wound and blind him." 

Such were some of the strange and curious customs of the people 
of Florida more than three and one-half centuries ago. 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOL. 81, NO. 4, PL. 1 




^^J-yuiAaV'i^ 



■g i^fi /F /* ^'~ , ^ f f ' /h ^ f^ \ ' li t 






iitf -" - 



H A^^ X^ ^^i?4i^,^ -«w;^-^^v<A^ML._ 



Size 10 by 7 inches 



SATURIOUA 



NO. 4 JACQUES LEMOYNE DE MORGUES— BUSHNELL 9 

Unfortunately the history of this very interesting d^-^*'* "™ j); 
the author's collection, is not known; however, it ts poss.b e o reach 
ertain conclttsions regarding its origin. The legend ,s ,n tahan and 
this offers a clue as to the time the picture was -«."^"y ^^e^ ^^ 

The youthful Charles IX was K,ng of France m ■ 564. *e year of 
the French expedition utrder Laudonmere to Florida, but all were 
dominated by the Oueen-mother, Catherine de' Med.c, surrounded as 
she was by gronps"of Italians who had accotjrpanied or followed her 
to France. Italian was spoken at the French Court. 

Lemoyne had accompanied the expedmon to Florida for the pur 
nose of preparing a series of drawitrgs and sketches, these, as he h,m- 
self w J " I showed his majesty, when, after having escaped from 
the remarkable perfidies and atrocious cruelties of the Spaniards, I 
re urTto Fr^tce." And it may be assumed that all such work, 
^h Exhibited at Court, bore legends written in ^^^^ l^^^^Zs 
in. of Satwwua Re ddia Florida, may have been one of the sketches 

'n: ^^TXibie to -~ r^y^^^^^^^^^^^^ 

was able to save any drawings. All his possessions appear to have 

""^L"':;' S^mrLt starting for war, the subject of the drawing 
J :e rci'ticed, occurred late in August, .564. LH. le -- 'tan ^ 
mnnths later early in November, the second of the French vessels 

tZti suggested that the picture may have been made after 
LaiXn i e aitd his small party, including Lemoyne, had returned 

and associates. 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 

VOLUME 81, NUMBER S 



THE RELATIONS BETWEEN THE 

SMITHSONIAN INSTITUTION AND 

THE WRIGHT BROTHERS 



BY 

CHARLES G. ABBOT 

Secretary, Smithsonian Institution 




(Publication 2977) 



CITY OF WASHINGTON 

PUBLISHED BY THE SMITHSONIAN INSTITUTION 

SEPTEMBER 29, 1928 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 

VOLUME 81, NUMBER 5 



THE RELATIONS BETWEEN THE 

SMITHSONIAN INSTITUTION AND 

THE WRIGHT BROTHERS 



BY 

CHARLES G. ABBOT 

Secretary, Smithsonian Institution 






(Publication 2977) 



CITY OF WASHINGTON 

PUBLISHED BY THE SMITHSONIAN INSTITUTION 

SEPTEMBER 29, 1928 



BALTIUORB, HD., U. S. A. 



I 



PREFATORY NOTE 

This statement represents an attempt on the part of the 
Smithsonian Institution to clarify an unfortunate con- 
troversy, and to correct errors where errors have been 
made, in order to do justice alike to three great pioneers 
of human flight — Wilbur and Orville Wright, and Samuel 
Pierpont Langley — as well as to the Smithsonian Insti- 
tution. 



THE RELATIONS BETWEEN THE SMITH- 
SONIAN INSTITUTION AND THE 
WRIGHT BROTHERS 
By CHARLES G. ABBOT 

Secretary, Smithsonian Institution 

For several months past, beginning- February 13, 1928, 
when I first addressed Mr, Orville Wright, a month after 
my election as Secretary, I have sought to end the so-called 
Langle3^-Wright controversy. In a friendly, personal con- 
ference with Mr. Orville Wright on April 19, he explained 
to me the points regarding which he feels that the Smith- 
sonian Institution has dealt unjustly with the Wright 
brothers, and stated that what he termed a " correction 
of history " by the Smithsonian was essential. 

So far as I am aware, all men agree that on December 17, 
1903, at Kitty Hawk, North Carolina, Orville and Wilbur 
Wright, alternately piloting their plane, made the first sus- 
tained human flights in a power propelled heavier-than-air 
machine. 

These successful flights by the Wright brothers came as 
the culmination of : ( i ) Their extensive laboratory experi- 
ments to determine the behavior of plane and curved sur- 
faces in air. (2) Their numerous gliding flights during 
several years at Kitty Hawk and elsewhere. (3) Their 
original design and construction of their flying machine 
and of the engine and propellers. 

The Smithsonian Institution has recognized these 
achievements in the following manner : 

I. By printing articles by Wilbur and Orville Wright in 
the Smithsonian Annual Reports. (See Smithsonian An- 
nual Reports, 1902, pp. 133-148; 19 14, pp. 209-216.) 

Smithsonian Miscellaneous Collections, Vol. 81, No. 5 



2 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

2. By printing other articles descriptive of their achieve- 
ments. (See Smithsonian Annual Reports, 1903. pp. 179- 
180; 1908, p. 133; 1910, pp. 147-151, 160-161.) 

3. By making- the first award of the Langiey gold medal 
for aeronautics to Wilbur and Orville Wright. This award 
was made on February 10, 1909, and the medal was for- 
mally presented on February 10, 19TO. (See Smithsonian 
Annual Reports, 1909, pp. 22, 107, 11 1; 1910, pp. 22-23, 
104-110.) 

4. By formal vote of the Board of Regents, March 15, 
1928, as follows: 

Whereas, To correct any erroneous impression derived from 
published statements that the Smithsonian Institution has denied 
to the Wright brothers due credit for making the first successful 
human flight in power-propelled heavier-than-air craft ; 

Resolved, That it is the sense of the Board of Regents of the 
Smithsonian Institution that to the Wrights belongs the credit of 
making the first successful flight with a power-propelled heavier- 
than-air machine carrying a man. 

5. By requesting the Wright brothers to furnish for ex- 
hibit in the National Museum the originals or models of 
any planes made by the Wrights up to 19 10, the selection 
to be at their discretion. (The request specifically included 
the Kitty Hawk plane. See pages 5 and 6 following, for 
letters of Secretary Walcott to Wilbur Wright of March 7, 
1910, and April 11, 1910.) 

6. By exhibiting in the National Museum the plane flown 
at Fort Myer in 1908 by Orville Wright, which is the first 
airplane bought for military purposes by any government. 

7. By exhibiting since 1922 in the National Museum 
twelve double-sided frames containing forty-nine photo- 
graphs showing the circumstances of the Kitty Hawk and 
Fort Myer flights. 

Mr. Wright feels, however, that the Smithsonian Insti- 
tution has appeared to be engaged in propaganda with the 



NO. 5 SMITHSONIAN INSTITUTION AND WRIGHT BROTHERS 3 

Object Of exalting Langley at the expense of himself and his 
brother as follows : 

1 By predominant mention of the achievements of 
Langley in the addresses at the time of the first presenta- 
tion of the Langley medal. 

2 By a misleading account of the exercises of Febru- 
ary lo, 1910, printed in the Smithsonian Annual Report 

""^'^iTv what he regarded as the lack of cordiality in an 
invitation by Secretary Walcott in April, 1910, to the 
Wright brothers to deposit the Kitty Hawk or othei 
planes in the U. S. National Museum. 

4 By the contract, in 1914, for experiments with the 
Langley machine made with Mr. Glenn Curtiss at that 
time a defendant in a patent suit brought by the Wright 

brothers. . n r ^u 

5 By claims of priority in capacity to hy, ±or tne 
Langley machine, based on the experiments of 1914, and 
repeated in Smithsonian publications as well as on labels 
in the National Museum. _ 

6. By failure to recognize properly the abilities of the 
Wrights as research men. 

I propose to take up these points seriatim: • 
1 Mr Wright's feeling that predominant mention of the 
achievements of Langley was made at the presenta- 
tion of Langley medals to him and his brother. 

The main address on February 10, 1910,^ was by the late 
Dr Alexander Graham Bell, a friend of Langley, a close 
observer of his experiments for a period of ten years, and a 
Regent of the Smithsonian Institution. The occasion was 
the first award of a gold medal bearing Langley's name 
which had been established at the suggestion of Dr. Bell 
to perpetuate Langley's place in aeronautics. Responding 
to a feeling then prevalent that Langley, on account of the 

^ See Smith^^n Annual Report, 1910, PP- 104-108. 



4 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

ill success of his experiments of 1903, had met with unjust 
ridicule, and doubtless inspired also by the partiality of a 
friend, it cannot be denied that Dr. Bell made less promi- 
nent in comparison with Langley's achievements the suc- 
cessful pioneer work of the Wrights than he might well 
have done appropriately on that occasion. But Dr. Bell 
was not lacking in appreciation of the Wrights. In the 
following letter recommending establishment of the Lang- 
ley medal he suggests the fitness of awarding it to the 
Wright brothers : 

Beinn Bhreagh, 

Near Baddeck, 
Nova Scotia, 

December 5, 1908. 

Hon. C. D. Wakott, 

Secretary, Smithsonian Institution, 

Washington, D. C. 

Dear Secretary Walcott : 

The Wright brothers are being deservedly honored in Europe. 
Can not America do anything for them? Why should not the 
Smithsonian Institution give a Langley medal to encourage avia- 
tion ? 

Yours, sincerely, 

Alexander Graham Bell, 

(See Smithsonian Annual Report, 1909, p. 107.) By refer- 
ence to the same Report ' it will be seen also how strongly 
Senator Lodge felt in regard to the merits of the Wright 
brothers. 

2. Mr, Wright's feeling that the summary of the exercises 
of February 10, 1910, printed in the Smithsonian 
Annual Report of 1910 was misleading. 

I acknowledge with regret that the summary of the pro- 
ceedings given at an earlier page of the Smithsonian An- 
nual Report for 19 10 (pp. 22-23) is misleading. The sum- 
mary quotes the following words from Mr. Wilbur Wright : 

'Smithsonian Annual Report, igog, p. iii. 



NO. 5 SMITHSONIAN INSTITUTION AND WRIGHT BROTHERS 5 

" The knowledge that the head of the most prominent sci- 
entific institution of America beheved in the possibiHty of 
human flight was one of the influences that led us to under- 
take the preliminary investigation that preceded our active 
work. He recommended to us the books which enabled us 
to form sane ideas at the outset. It was a helping hand at 
a critical time, and we shall always be grateful." 

From the context it would appear that Mr. Wright made 
this statement at the ceremony. This was not the case. 
Actually the statement was quoted by Dr. Bell in his speech 
from an extract of a private letter from the Wright brothers 
which Dr. Octave Chanute had quoted at the Langley Me- 
morial meeting, December 3, 1906.' The full statement 
made by Wilbur Wright at the ceremony is given as ap- 
proved by him at pages 109-110 of the same Smithsonian 
Annual Report, that for 19 10. 

Mr. Orville Wright assures me that though he and his 
brother both drew encouragement from the fact that so 
celebrated a scientific man as Dr. Langley had adventured 
his reputation in the field of heavier-than-air aviation, the 
Wrights did not rely on Langley's experimental data or 
conclusions, but made laboratory researches of their own, 
on which their constructions were based exclusively. I fully 
accept this assurance as a true statement of historical fact. 

3. Mr. Wright's feeling that Secretary Walcott's invita- 
tions to deposit the Kitty Hawk and other planes in 
the National Museum lacked cordiality. 

The letters referred to are as follows : 

Smithsonian Institution, 
Washington, U. S. A., 

March 7, 1910. 
My dear Mr. Wright : 

The National Museum is endeavoring to enlarge its collections 
illustrating the progress of aviation and, in this connection, it has 



^ See Smithsonian jMiscellaneous Collections, \'ol. XLIX, Art. IV, Publ. 
No. 1720, p. 32. 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

been suggested that you might be willing to deposit one of your 
machines, or a model thereof, for exhibition purposes. 

The great public interest manifested in this science and the 
numerous inquiries from visitors for the Wright machine make it 
manifest that if one were placed on exhibition here it would form 
one of the most interesting specimens in the national collections. 
It is sincerely hoped that you may find it possible to accede to this 
request. 

With kindest regards, I am 

Very truly yours, 

Charles D. Walcott, 
Mr. Wilbur Wright, Secretary. 

Dayton, Ohio. 

Dayton, Ohio, 
March 26, 1910. 
Mr. Charles D. Walcott, 
Washington, D. C. 

My dear Dr. Walcott : 

Your letter of the 7th of this month has been received. If you 
will inform us just what your preference would be in the matter of 
a flier for the National Museum we will see what would be possible 
in the way of meeting your wishes. At present nothing is in con- 
dition for such use. But there are three possibilities. We might 
construct a small model showing the general construction of the 
airplane, but with a dummy power plant. Or we can reconstruct 
the 1903 machine with which the first flights were made at Kitty 
Hawk. Most of the parts are still in existence. This machine would 
occupy a space 40 feet by 20 feet by 8 feet. Or a model showing 
the general design of the latter machine could be constructed. 

Yours truly, 

Wilbur Wright. 

Smithsonian Institution, 
Washington, U. S. A., 

April II, 1910. 
Dear Mr. Wright : 

Yours of March 26th came duly to hand, and the matter of the 
representation of the Wright airplane has l)een very carefully con- 
sidered by Mr. George C. Maynard, who has charge of the Division 
of Technology in the National Museum. I told him to indicate 
what he would like for the exhibit, in order that the matter might 



NO. 5 SMITHSONIAN INSTITUTION AND WRIGHT BROTHERS 7 

be placed clearly before you and your brother. In his report he 
says : 

The following objects illustrating the Wright inventions would make a 
very valuable addition to the aeronautical exhibits in the Museum: 

1. A quarter-size model of the airplane used by Orville Wright at Fort 
Mj'cr, Virginia, in September, 1908. Such a model equipped with a 
dummy power plant, as suggested by the Wrights, would be quite suitable. 

2. If there are any radical differences between the machine referred to 
and the one used at Kitty Hawk, a second model of the latter machine 
would be very appropriate. 

3. A full-size Wright airplane. Inasmuch as the machine used at Fort 
Myer has attracted such world-wide interest, that machine, if it can be 
repaired or reconstructed, would seem most suitable. If, however, the 
Wright brothers think the Kitty Hawk machine would answer the pur- 
pose better, their judgment might decide the question. 

4. If the Wright brothers have an engine of an early type used by them 
which could be placed in a floor case for close inspection that will be 
desirable. 

The engine of the Langley Aerodrome is now on exhibition in a 
glass case and the original full-size machine is soon to be hung in 
one of the large halls. The three Langley quarter-size models are 
on exhibition. The natural plan would be to install the different 
Wright machines along with the Langley machines, making the 
exhibit illustrate two very important steps in the history of the 
aeronautical art. 

The request of Mr. Maynard is rather a large one, but we will 
have to leave it to your discretion as to what you think it is 
practicable for you to do. 

Sincerely yours, 

Charles D. Walcott, 
Mr. Wilbur Wright. Secretary. 

1127 West Third Street, 
Dayton, Ohio. 

I cannot but feel that Mr. Wright has erred in ascribing 
to Dr. Walcott any but a sincere invitation to the Wrights 
to make their own selection of whatever they thought best 
suited and most available to deposit in the National Museum 
for the purpose of illustrating their achievements. It is to 
be recalled, too, that in 1910 the world w^as ringing with the 
triumphant demonstrations of the Wrights at Fort Myer 
and in France of ability to make long-continued air flights. 
At that moment the Fort Myer plane was far more cele- 



8 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

brated than the Kitty Hawk plane. Now, of course, all is 
changed. We have the Fort Myer plane. But it is pro- 
foundly regretted by patriotic Americans that the Kitty 
Hawk plane is not in a place of honor in the United States 
National Museum. 

4. Mr. Wright's feeling that the contract to test the 
Langley plane in 19 14 with j\Ir. Glenn Curtiss, then 
a defendant in a suit w^ith the Wrights, was un- 
friendly to them. 

I concede to Mr. Wright that it lacked of considera- 
tion to put the tests of the Langley plane into the hands of 
his opponent, Mr. Curtiss. As early as 1908 Dr. Walcott 
had had correspondence w'ith Mr. Manly and with Dr. 
Chanute on the desirability of further experiments with the 
Langley Aerodrome under Manly's direction. Lack of 
means, from w^hich the Smithsonian then as now suffered, 
doubtless stood in the way. Without having been familiar 
myself with all the circumstances at that time, I believe it 
was owing to the fact that Mr. Curtiss had the available 
plant and Manly had not, so that the former could make the 
tests at smaller expense than the latter, that Dr. Walcott 
determined to place the machine in Curtiss' hands for trial. 
The Smithsonian paid Mr. Curtiss $2,000 to make the ex- 
periments. Yet the fact that the results of these tests might 
prove valuable to Mr. Curtiss in his defense against Mr. 
Wright's suit, and the unfavorable aspect in which that 
might put the Smithsonian Institution, if foreseen, might 
well have deterred from the course of action adopted. The 
appointment of Dr. A. F. Zahm to represent the Smith- 
sonian as official observer at the Hammondsport tests has 
been criticized. At that time Dr. Zahm, a recognized aero- 
nautic authority, was the official recorder of the Langley 
Aeronautical Laboratory of the Smithsonian Institution, 
a position he had held since May, 191 3, so that his appoint- 
ment as indicated was natural. 



NO. 5 SMITHSONIAN INSTITUTION AND WRIGHT BROTHERS 9 

As to the propriety of testing Langley's machine in 1914, 
some have objected on the ground that it was a precious 
specimen, taken from the National Museum to be wantonly 
subjected to destruction. This is not true. The machine, 
excepting its engine, was never on public exhibition until 
1918. In 1904 it was specifically placed by the War Depart- 
ment ' at the disposal of the Smithsonian for further tests. 
It had been kept continuously in the shops where it was 
made from the winter of 1903 until it was taken to Ham- 
mondsport. 

In 1914 airplane construction had not reached the com- 
paratively standardized stage of the present day. It was 
then thought possible that the tandem, dragon-fly type of 
the Langley Aerodrome had merits which should be devel - 
oped. There was also the thought that a decisive success 
might rescue from unmerited ridicule Langley's fame. 
These, I submit, were circumstances very properly inviting 
the making of the tests. But I feel that it was a pity that 
Manly, Dr. Langley's colleague, could not have been the 
man chosen to make them. 

5. Mr. Wright's feeling that claims in priority of capacity 
to fly for the Langley machine based on 1914 experi- 
ments were unjustified and prejudicial to the Wright 
brothers. 

The claims published by the Smithsonian relating to the 
1914 experiments at Hammondsport were sweeping. In the 
Report of the U. S. National Museum for 19 14, page 47/ 

' It is frequently erroneously stated that the Congress appropriated $100,000 
to Langley for his experiments. The sum of $50,000 allotted to him by the 
Board of" Ordnance and Fortifications of the War Department was all the 
public money that he ever had for the purpose. There was no direct Congres- 
sional appropriation whatever. 

^See also Smithsonian Annual Report, 1914. PP- 9-io and 217-222; also the 
label of the full-sized Langley machine as first installed in 1918 in the Na- 
tional Museum, hereafter quoted. 



lO SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

we read: " Owing to a defect in the launching- apparatus, 
the two attempts to fly the large machine during Dr. Lang- 
ley's life proved futile, but in June last, without modifica- 
tion, successful flights were made at Hammondsport, N. Y." 
Certainly this was not literally true, but Assistant Sec- 
retary Rathbun, who wrote the statement given above, I am 
certain believed this to be true. There were, however, many 
differences. (I refer only to the first tests when the original 
Langley-Manly engine was used.) Mr. Wright claims that 
essential changes tending to improve the chances of success 
were made on the basis of knowledge gained subsecjuent to 
1903. 

Some of the differences were favorable, some unfavor- 
able, to success. Just what effects, favorable or unfavor- 
able, the sum total of these changes produced can never be 
precisely known. In the opinion of some experts, the tests 
demonstrated that Langley's machine of 1903 could have 
flown, and in the opinion of others, these tests did not 
demonstrate it. It must ever be a matter of opinion. 

In 19 18, the Langley plane, reconstructed as nearly as 
possible as of 1903, using all available original parts, by 
Mr. R. L. Reed, the foreman who had most to do with it in 
Langley's time, was exhibited in the U. S. National Museum 
with this label: 

THE ORIGINAL, FULL-SIZE. 
LANGLEY FLYING MACHINE. 1903 

Later this label was amplified to read as follows: 

ORIGINAL LANGLEY 
FLYING MACHINE. 1903 



THE FIRST MAN-CARRYING AEROPLANE IN THE HISTORY OF THE 
WORLD CAPABLE OF SUSTAINED FREE FLIGHT. INVENTED, BUILT, AND 
TESTED OVER THE POTOMAC RIVER BY SAMUEL PIERPONT LANGLEY IN 
1903. SUCCESSFULLY FLOWN AT HAMMONDSPORT, N. Y., JUNE 2, I9I4. 
DIMENSIONS: 55 FEE,T LONG, 48 FEET WIDE; SUSTAINING WING SUR- 
FACE, 1,040 SQUARE FEET. 



NO. 5 SMITHSONIAN INSTITUTION AND WRIGHT BROTHERS II 

Vigorous criticism of the statements made by the Smith- 
sonian relative to the test of 1914, and the capabiHty of 
flight of Langley's machine having appeared, Dr. Walcott 
in 1925 asked Dr. j. S. Ames and Achiiiral David W. 
Taylor, members and now Chairman and Vice-Chairman, 
respectively, of the National Advisory Committee for Aero- 
nautics, to examine the circumstances and report. Their 
conclusions were summarized in the following letter, sup- 
ported by several appendices which are printed herein, the 
whole of which was given to the press by Dr. Walcott on 
June 9, 1925. 

Washington, D. C, 

June 3, 1925. 
Dr. Charles D. Walcott, 
Secretary, Smithsonian Institution, 
Washington, D. C. 

Dear Doctor Walcott : 

The announcement that Mr. Orville Wright had arranged to have 
the first Wright airplane deposited in a British museum having 
aroused considerable controversy as to the accuracy of the label 
attached to the Langley flying machine now on exhibition in the 
Smithsonian Institution, you have asked us to examine the Langley 
machine, look into its history, and advise you whether we consider 
it desirable to modify the present label. 

We have made a careful study, not only of the history of the 
Langley machine itself, but also of all the circumstances connected 
with its tests. We append to this letter (Appendix I) a suggested 
modified label, and a statement of our views and conclusions (Ap- 
pendix II), upon which our recommendation is based. 

There is no question but that the Wrights were the first to navi- 
gate the air, thus reaching the goal long sought by many, but in our 
opinion, when Langley's 1903 machine was wrecked in launching, 
he too, after years of effort, following a different road, was in sight 
of the same goal. He was like the prophet of old who, after forty 
years of wandering in the wilderness, was permitted to view the 
promised land upon which he never set his foot. Langley's accom- 
plishments in aeronautics were notable, and he is entitled to full 
credit for them. We believe that the Langley machine of 1903 
was capable of sustained flight had it been successfully launched, 
and it is naturally fitting that the Smithsonian Institution should 



12 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

perpetuate with pride, by exhibiting his models and flying machine, 
suitably labeled, the aeronautical achievements of its distinguished 
secretary. 

It is unfortunate that in the past the situation has been beclouded 
by patent litigation, in which the Smithsonian Institution had no 
part, involving temptation for one side to exaggerate and distort 
favorably Langley's work, and for the other side to belittle and deny 
it. While bitterness thus engendered survives, it cannot be expected 
that any label can be placed upon Langley's machine that will be 
fully acceptable to everyone. The appended suggested label departs 
from the customary brief title in two respects. In the first place, 
it is much longer and goes more into the history of the exhibit 
than is customary. In the second place, in view of the facts that' 
the exhibit deals with the border line between success and failure 
of man's effort to fly, and that the original Wright machine, a 
purely American product and the first to fly, is destined to a museum 
in another country, we have suggested that the label on the Langley 
machine, also a purely American product and capable of flight but 
not successfully flown, contain an explicit and definite statement, 
which would be unnecessary under other circumstances, giving to 
the Wrights the credit due them as the first to fly, on December 17, 
1903. 

It is our earnest hope that this proposed restatement of the label 
will prove satisfactory both to yourself and to Mr. Orville Wright, 
with both of whom we have had such friendly relations on the Na- 
tional Advisory Committee for Aeronautics and in whose judgment 
and fairness of mind we have such implicit confidence. 

Respectfully yours, 
(Signed) Joseph S. Ames 
Professor of Physics, 

Johns Hopkins University. 
(Signed) D. W. Taylor 
Rear Admiral (C C.) U. S. N., Retired. 



NO. 5 SMITHSONIAN INSTITUTION AND WRIGHT BROTHERS I3 



APPENDIX I 

{Ames-Taylor Report) 
LABEL 



LANGLEY FT.VING MACHINE 

THE ORIGINAL. LANGLEY FLYING MACHINE OF I903, RESTORED. 
IN THE OPINION OF MANY COMPETENT TO JUDGE, THIS MACHINE 
WAS THE FIRST HEAVIER-THAN-AIR CRAFT IN THE HISTORY OF THE 
WORLD CAPABLE OF SUSTAINED FREE FLIGHT UNDER ITS OWN 
POWER, CARRYING A MAN. 

THIS MACHINE SLIGHTLY ANTEDATED THE WRIGHT MACHINE 
DESIGNED AND BUILT BY WILBUR AND ORVILLE WRIGHT, WHICH, ON 
DECEMBER I7, I9O3, WAS THE FIRST IN THE HISTORY OF THE WORLD 
TO MAKE A SUSTAINED FREE FLIGHT UNDER ITS OWN POWER. 
CARRYING A MAN. 

Langley's machine was designed by Samuel Pierpont Langley, 
Secretary of the Smithsonian Institution, and completed in 1903. 
The original machine was never successfully launched into the air : 
attempts at launching with a catapult on October 7 and December 
8, 1903, were failures owing to defects in the operation of the 
catapult launching device, and the machine was damaged severely. 
In 1914, using all available parts remaining, the machine was re- 
constructed, with certain modifications, and with hydroplane floats 
attached for the purpose of enabling it to rise from the water in- 
stead of being launched by a catapult. In that condition, and carry- 
ing a man, it was successfully flown with the original power plant, 
at Hammondsport, New York, June 2, 191 4, and photographed in 
flight. With a modified and more powerful power plant, it was 
subsequently flown repeatedly. These tests indicated that the 
original airplane would have flown if successfully launched in the 
tests of 1903. After the Hammondsport flights the pontoons were 
removed and the airplane was restored in accordance with original 
drawings and data to its original condition, and is constructed in 
the main of the original parts. 



14 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

Washington, D. C, 

June 3, 1925. 
APPENDIX II 

( Ames-Taylor Report ) 

THE LANGLEV FLYING MACHINE. 

Memorandum for Dr. Charles D. Walcott, 
Secretary, Smithsonian Institution. 

1. In connection with our letter to you of even date, concerning 
the label on the Langley Flying Machine in the National Museum, 
we beg to add the following remarks of an historical nature, and our 
views and conclusions in some detail. 

2. Professor S. P. Langley became actively interested and en- 
gaged in the study of aeronautics in 1887, and was assiduous in 
the theoretical and experimental study of the subject till his death 
in 1906. The more important of his results were finally published 
in Volume 27 of " Smithsonian Contributions to Knowledge," 
Part I, issued in 1891, entitled " Experiments in Aerodynamics " ; 
Part 2, the " Internal Work of the Wind," 1893 ; and Part 3, the 
"Langley Memoir on Mechanical Flight," 191 1. In the course 
of his study he became convinced of the possibility of " mechanical 
flight," /. e., of constructing a heavier-than-air machine, to be 
driven by an engine, and sufficiently powerful and stable to carry a 
man. To this end he constructed certain models about 12 feet 
wide by 15 feet long, weighing approximately 30 pounds, each 
driven by a 1^ horsepower steam engine which with its boiler 
weighed not over 7 pounds per horsepower. These models actually 
did fly, in one case as long as i minute and 49 seconds and for a 
distance of 4,300 feet. These two machines made successful 
flights on May 6. 1896, in the presence of Dr. A. Graham Bell, and 
on November 28, 1896, in the presence of Mr. Frank G. Carpenter. 
The model machines numbered 5 and 6 were placed on exhibition 
in the National Museum on April 21, 1905. Finally, by the aid of 
a grant of $50,000 made by the Board of Ordnance and Fortification 
of the War Department in December, 1898, which was later sup- 
plemented by funds to the amount of $20,000 from the Smithsonian 
Institution, he constructed in the years from 1898 to 1903 a full- 
size flying machine (which he called an "aerodrome"), a repro- 
duction on a scale approximately 4 : i of these steam models which 
had previously flown in 1896. The engine of this final machine 
was a radial 5 cylinder, water cooled, gasoline type. 5 inch bore 
^^y 52 i"ch stroke, developing 52.4 horsepower at 950 r. p. m., and 



NO. 5 SMITHSONIAN INSTITUTION AND WRIGHT BROTHERS 1 5 

weighing 125 pounds, oi" 2.2 pounds per horsepower. This engine 
was designed and built by Mr. Charles M. Manly at the Smith- 
sonian shops. Two tests were attempted with this flying machine, 
Mr. Manly being the pilot in both cases. 

3. The machine was designed to obtain its initial impetus by 
means of a spring-catapult propelling it along a pair of rails on top 
of a house boat. The first test was conducted in the middle of the 
Potomac River, opposite Widewater, Virginia; and suitable pro- 
vision was made for the flotation of the machine upon its landing 
on the surface of the river as it was intended to do. The second 
test was made on December 8, 1903, off the Arsenal Point in the 
Potomac River at the junction of the Georgetown Channel and the 
Eastern Branch. A full description of the machine and the tests 
is given in " Langley Memoir on Mechanical Flight," published in 
191 1. Both attempts to launch the machine failed. The first on 
October 7, 1903, failed because a lug on a pin projecting from the 
bottom of the lower front guy post hung in its slot on a support 
on the launching car or catapult, causing the front wings to be 
badly twisted from a positive angle of lift to a negative angle of 
depression, thus forcing the front end of the machine downwards 
instead of supporting it, and resulting in the machine striking the 
water about 150 feet in front of the house boat from which it was 
launched. The front wings and propellers were broken by the im- 
pact and the rear wings and control surfaces were destroyed by 
towing the machine through the water. The second test on Decem- 
ber 8, 1903, failed for reasons which were never absolutely deter- 
mined. Photographs of the operation show clearly, however, that 
the immediate cause was the collapse of the rear part of the machine. 
This was probably due to a sudden gust of wind striking it and 
throwing it against a stanchion as it passed down the launching 
track, while it was still in contact with the catapult. Thus, no evi- 
dence was obtained of the aerodynamic or other features of the 
machine itself. Further study at the time was not possible because 
funds were exhausted and the public prejudice against the work 
made it impossible for Dr. Langley to raise either public or private 
funds. 

4. The machine was drawn from the water in its damaged con- 
dition the night of December 8, 1903. A few days later it was re- 
moved to the shops of the Smithsonian Institution where the frame 
was repaired and the engine, which had not been injured, was 
stored for further use till such time as additional funds might be- 
come available to build new wings and to defray the expenses of 



l6 S:>IITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

further tests. Official dispositicjii of that i)art oi the machine belong- 
ing to the War Department was made on March 23, 1904. when 
by formal letter of the Board of Ordnance and Fortification, signed 
by Major General G. S. Gillespie, President of the Board, and 
addressed to Dr. Langley, the Board stated that " .... all of the 
material procured for experiments with the aerodrome from allot- 
ments of this Board will be left in your possession, in order that 
it may be available for any future work which you may be able to 
carry on in the solution of the problem of mechanical flight ; unless, 
of course, the Board of Ordnance and Fortification shall otherwise 
direct, but until such action be taken there will be no necessity for 
a separation or distribution of the property so far as the Board is 
concerned." 

5. It would seem from the above that at that time there was 
expectation that further tests would be made with the machine. 

6. The machine had in the meantime been cleaned and restored 
to its original condition, except for the necessary wings and con- 
trol surfaces. The ribs and cloth covering on the original wings 
and control surfaces had been so damaged as to require replacement, 
but the metal fittings were all saved for rebuilding the wings when 
it might become possible. 

7. The engine was shipped to New York in 1906 and exhibited at 
the first aeronautical show which was held at the Grand Central 
Palace by the Aero Club of America. It was then returned to 
Washington and placed on temporary exhibition in the National 
Museum, but the rest of the machine remained in the Smithsonian 
shops and was not then placed on exhibition in the National 
Museum. 

8. It appears that as early as 1908 the Smithsonian Institution 
contemplated making further tests with the Langley Flying 
Machine. This is evident from a memorandum of September 14. 
1908, signed by Cyrus Adler, addressed to Mr. Rathbun, at the 
Smithsonian Institution, which reads as follows : 

" September 14, 1908. 
" For Mr. Rathbun : 

" I had a talk today with Mr. Chanute, the gist of which I should 
like to put on record. 

" He spoke of Mr. Manly's desire to fly Mr. Langley's flying 
machine just as it was constructed in order to demonstrate that it 
could have flown. Mr. Chanute said that in his opinion Mr. Lang- 
ley's machine could fly just as it was constructed, and this had been 



NO. 5 SMITHSONIAN INSTITUTION AND WRIGHT BROTHERS I7 

demonstrated by the fact that a Frenchman has built a machine 
exactly Uke Mr. Langley's which has flown, but he believed further 
that the machine would be wrecked in alighting. 

" I thought you might care to have this because it is more than 
likely that before very long, through the War Department or in 
some other way, the question of trying the machine will be forcibly 
brought up. 

Very truly yours, 

Cyrus Adler." 

This is further evidenced by the following correspondence between 
Dr. Walcott and Dr. Octave Chanute, one of the pioneers in flying 
experiments : 

" November 16, 1908. 
" Dear Dr. Chanute : 

" In a letter received during the summer while I was away from 
the city, Mr. Charles M. Manly says : 

The Langley machine is today capable of more than any other machine 
yet built, and is apt to remain so for some time. The engine is now seven 
years old and still is the peer of the world. 

" Mr. Manly has suggested that he be permitted to make trial tests 
of the Langley machine at some future time. I write to ask whether 
in your judgment it would be wise to have an attempt made to fly 
with it. 

Sincerely yours, 

Chas. D. Walcott." 

" Chicago, Illinois, 
November 20, 1908. 
" Mr. Chas. Walcott, 
Secy., Smithsonian Instn., 
Washington, D. C. 

" Dear Sir: 

" I have your letter of the i6th, asking whether in my judgment, 
it would be wise to make an attempt to fly with the Langley machine. 

" I have never seen this machine but I suppose that I understand 
it fairly well from descriptions. 

" My judgment is that it would probably be broken when alight- 
ing on hard ground and possibly when alighting on the water, al- 
though the operator might not be hurt in either case. 

"If the Institution does not mind taking this risk and suitable 
arrangements can be made about the expense. I believe that it 



i SMlTHSOxNlAN MISCELLANEOUS COLLECTIONS VOL. 8l 

would be desirable to make the test, in order to demonstrate that the 
Langley machine was competent to fly and might have put our gov- 
ernment in possession of a type of flying machine, which, although 
inferior to that of the Wrights, might have been evolved into an 
efl^ective scouting instrument. 

Yours truly, 

O. Chanute." 

" November 27, 1908. 
" Dear Sir : 

" I wish to thank you for your letter of November 21. in relation 
to the Langley machine. I will talk the matter over with Air. Manly 
the next time I see him. 

Very truly yours. 

Chas. D. Walcott." 
" Doctor Octave Chanute, 
61 Cedar Street. 
Chicago, Illinois." 

9. In 1910, the Smithsonian Institution made an effort to secure 
the original Wright machine of 1903, or a model thereof for ex- 
hibition in the National Museum. This is evidenced by the follow- 
ing correspondence between Dr. Walcott and Mr. Wilbur Wright : 

" Smithsonian Institution, 
Washington, U. S. A., 

March 7, 1910. 
" My dear Mr. Wright : 

" The National Museum is endeavoring to enlarge its collections 
illustrating the progress of aviation and, in this connection, it has 
been suggested that you might be willing to deposit one of your 
machines, or a model thereof, for exhibition purposes. 

" The great public interest manifested in this science and the 
numerous inquiries from visitors for the W^right machine make it 
manifest that if one were placed on exhibition here it would form 
one of the most interesting specimens in the national collections. 
It is sincerely hoped that you may find it possible to accede to this 
request. 

" With kindest regards, I am 

V^ery truly yours, 

Charles D. Walcott, 
" Mr. Wilbur Wright. Secretary." 

Dayton, Ohio." 



NO. 5 SMITHSONIAN INSTITUTION AND WRIGHT BROTHERS KJ 

" Dayton, Ohio, 

March 26, 1910. 
" Mr. Charles D. Walcott, 
Washington, D. C. 

" My dear Dr. Walcott : 

" Your letter of the 7th of this month has heen received. If you 
will inform us just what your preference would be in the matter 
of a flier for the National Museum we will see what would be 
possible in the way of meeting your wishes. At present nothing 
is in condition for such use. But there are three possibilities. We 
might construct a small model showing the general construction of 
the" airplane, but with a dummy power plant. Or we can recon- 
struct the 1903 machine with which the first flights were made at 
Kitty Hawk. Most of the parts are still in existence. This machine 
would occupy a space 40 feet by 20 feet by 8 feet. Or a model show- 
ing the general design of the latter machine could be constructed. 

Yours truly, 

Wilbur Wright." 

" Smithsonian Institution, 
Washington, U. S. A., 

April II, 1910. 

" Dear Mr. Wright : 

" Yours of March 26th came duly to hand, and the matter of the 
representation of the Wright airplane has been very carefully 
considered by Mr. George C. Maynard, who has charge of the 
Division of Technology in the National Museum. I told him to 
indicate what he would like for the exhibit, in order that the matter 
might be placed clearly before you and your brother. In his report 
he says : 

The following objects illustrating the Wright inventions would make 
a very valuable addition to the aeronautical exhibits in the Museum : 

I \ quarter-size model of the airplane used by OrviUe Wright at hort 
Myer Virginia, in September, 1908. Such a model equipped with a 
dummy power plant, as suggested by the Wrights, would be quite smtable. 
^ If there are any radical differences between the machine referred to 
and the one used at Kitty Hawk, a second model of the latter macliine 
would be very appropriate. 

3 A full-size Wright airplane. Inasmuch as the machine used at I^ort 
Myer has attracted such world-wide interest, that machine, if it can be 
.repaired or reconstructed, would seem most suitable. If, however, the 
Wright brothers think the Kitty Hawk machine would answer the pur- 
pose better, their judgment might decide the question. 



20 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

4. If the Wright brothers have an engine of an early type used by them 
which could be placed in a floor case for close inspection that will be 
desirable. 

" The engine of the Langley Aerodrome is now on exhibition in 
a glass case and the original full-size machine is soon to be hung 
in one of the large halls. The three Langley quarter-size models are 
on exhibition. The natural plan would be to install the difit'erent 
Wright machines along with the Langley machines, making the 
exhibit illustrate two very important steps in the history of the 
aeronautical art. 

" The request of Mr. Maynard is rather a large one. but we will 
have to leave it to your discretion as to what you think it is prac- 
ticable for you to do. 

Sincerely yours, 

Charles D. Walcott, 

Secretary." 
" Mr. Wilbur Wright, 
1 127 West Third Street, 
Dayton, Ohio." 

10. Apparently, nothing developed from the above correspon- 
dence. Dr. Walcott's last letter quoted above was never replied to. 
It is a matter of grave regret that at that time the Wright brothers 
did not see their way to reconstruct and deposit in the National 
Museum their original full-size airplane, the first machine ever to 
fly successfully with a man, because then, in 1910, it would have 
been the only full-size flying machine on exhibition in the National 
Museum, the Langley machine being still in the shops of the Smith- 
sonian Institution awaiting further tests. 

11. In September, 191 1, the Smithsonian Institution secured and 
placed on exhibition in the National Museum the original Wright 
airplane that was tested at Fort Myer in 1908, and purchased by 
the War Department, being the first military airplane purchased 
by the Government. 

12. In January, 1914, the late Lincoln Beachey, one of the pioneer 
aviators, and others, again suggested that it would be of interest to 
determine by actual test whether the essential features of Professor 
Langley 's aerodynamic theory, as illustrated in his 1903 machine, 
were correct. Finally, at the initiative of the Smithsonian Insti- 
tution, the Curtiss Aeroplane Company was invited to submit a bid 
to refit the machine and to make tests. The formal letter to the 
Curtiss Aeroplane Company was dated March 31, 1914, and the 
reply offering to undertake the work for a price of $2,000, was 



NO. 5 SMITHSONIAN INSTITUTION AND WRIGHT BROTHERS 21 

written by Mr. G. H. Curtiss on April i, 19 14. The machine was 
thereupon sent to the shops of the Curtiss Aeroplane Company at 
Hammondsport, New York, on April 2, 1914, and the engine was 
shipped on April 13, 1914. 

13. In preparing the machine for flight with the original engine, 
certain modifications and additions were made. These were due, in 
the main, to the fact that, whereas the original machine was fitted 
for use with a catapult, these new tests were to be made from the 
surface of a lake, using hydroplaning floats. Therefore, certain 
changes were necessary to attach these floats to the machine and to 
properly inter-brace them and the supporting surfaces together. 

14. It is perfectly clear from the correspondence between the 
Smithsonian Institution and the Curtiss Aeroplane Company that 
no emphasis was placed upon the use of the original machine, as 
such, but that what was desired was knowledge concerning certain 
features of the Langley design, which was expressed in Dr. Wal- 
cott's letter of March 31, 1914, previously referred to, in the fol- 
lowing terms : 

" In connection with the reopening and development of work 
under the Langley Aerodynamical Laboratory, it seems desirable to 
make a thorough test of the principles involved in the construction 
of the Langley heavier-than-air man carrying flying machine, espe- 
cially the question as to the tandem arrangement of the planes, and 
general stability, especially longitudinal stability." 

15. A brief interesting account of the Hammondsport tests is 
contained in the Annual Report of the Smithsonian Institution for 
1914, pages 217 to 222. 

16. After the flights were discontinued in November, 191 5, the 
machine was returned to the Smithsonian shops on June 26, 1916. 
There it was completely overhauled. New wings and control sur- 
faces were built to the same form and size (with solid instead of 
hollow ribs to save the expense of the latter) so as to refit the 
machine for exhibition purposes in the National Museum and 
restore it as nearly as possible to its original condition as it was 
in 1903. As much of the original material was used as possible. 
When this overhaul was completed, it was placed on exhibition in 
the National Museum on January 15, 1918. 

17. It is seen that up to 191 5 the Langley machine was used 
solely and properly for the purposes intended by Professor Langley 
himself, for which it was originally turned over by the Board of 
Ordnance and Fortification which had defrayed the major portion 
of its cost. When all had been done to this end that was possible. 



22 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

the machine became properly an exhibit in the National Museum. 
It was never an exhibit until 1918. 

18. Previous to this date, there had been placed on exhibit in the 
Museum the two Langley steam-driven models which had success- 
fully flown in 1896, and the quarter-size model of the large machine 
equipped with its 3 horsepower radial gasoline engine. The first 
two of these are approximately, and the latter exactly, one-fourth 
the linear dimensions of the full-size machine. It is thus clear that, 
when in the letters from the Smithsonian Institution to Messrs. 
Wilbur and Orville Wright, of March 7 and April 11, 1910, the 
request was made for models of their successful machines, it was 
the hope to have both Langley and the Wright brothers represented 
in the Museum by exhibits of the same character. 

19. The question whether the original Langley machine of 1903 
was capable of flight under its own power and carrying a pilot has 
been a controversial one since, subsequent to the Hammondsport 
trials of 1914, there was litigation to which the Smithsonian Insti- 
tution was in no way a party, involving infringement, or alleged 
infringement of the Wright patents by other manufacturers, and 
since, in 192 1, the English patent attorney for the Wrights published 
a violent attack, with allegations of fraud, etc.. in connection with 
the Hammondsport trials. 

20. There are just three questions involved, which must be 
answered before it is possible to determine the capability of flight 
of the original Langley machine. These questions are : First, was 
the power plant adequate? Second, did the machine embody the 
pro])er aerodynamic principles to enable it to balance and maintain 
itself in the air? Third, was it sufficiently strong structurally to 
carry its weight and the stresses due to flying? 

21. As regards the power plant, there seems no question that, in 
the Hammondsport trials the original Manly engine never developed 
the power of which it was demonstrated to be capable in 1903. 
Furthermore, during the Hammondsport trials with the original 
engine, the weight lifted into the air, including the pontoons, was 
40 per cent greater than that of the machine as of 1903 with a 
pilot. Moreover, the bracing and supports to the pontoons and the 
pontoons themselves must have added materially to the resistance 
of the machine. If under these circumstances, the Langley machine 
was capable of arising from the water, which was demonstrated, 
there is no question in our mind that the 1903 machine had an 
adequate power plant. 



NO. 5 SMITHSONIAN INSTITUTION AND WRIGHT BROTHERS 23 

22. With reference to the second question, although there were 
some changes in the supporting and guiding surfaces in the Ham- 
mondsport machine as compared with those of the 1903 machme, 
they were not, in our judgment, material, either as regards the 
Hammondsport machine when fitted with the original Manly 
engine, or subsequently when modified by a more powerful engme 
with a tractor screw. Moreover, the machine as it stood was vir- 
tually an exact copy of a quarter-size model which had shown itself 
aerodynamically quite satisfactory. We conclude, accordingly, that 
the answer to the second of the fundamental questions above is 
also in the affirmative. 

23. When it comes to the question of strength, the case is not so 
clear. There is no question that the changes made in 1914 provided 
additional strength. Additional strength was obviously needed if 
40 per cent additional weight was to be carried. However, the 
fact that additional strength was provided renders it impossible to 
remove the third question from the realm of controversy. This is 
a question for technical experts. A complete wing, one-quarter of 
the sustaining area, showed, by sand load test, ability to carry a 
total weight of 260 pounds without damage, while one-quarter of 
the weight of the original machine and pilot was 207^ pounds, 
only. Subsequently, the Hammondsport machine with a much 
more powerful engine (a Curtiss 80 horsepower engine) and with 
only a moderate increase in strength, showed itself capable of 
flight carrying 1,520 pounds, or 85 per cent more weight than the 
original machine of 1903. These facts, in our opinion, establish 
a strong presumption in favor of the adequacy of the structural 
strength of the original machine. However, we have asked the 
disinterested head of the Design Section of the Bureau of Aero- 
nautics of the Navy Department, to study with his experts the 
original machine and give us their opinion as to the adequacy of 
the original structure They are of the opinion that structurally the 
original Langley flying machine was capable of level and controlled 

flight. 

24. It should not be thought that the original Langley machine 
■ was, in any sense, a finished product. Langley himself regarded 
his machine as only a beginning ; numerous problems had occurred 
to him which needed solution before aviation could be considered 
practicable. Since Langley and the Wright brothers looked at the 
subject from such different angles it would have been an inesti- 
mable advantage to the science and the art of aviation if Langley 
had been able to continue his work. 



24 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

25. In conclusion, we beg to call attention to the fact that a 
careful examination of the Langley machine now on exhibition in 
the National Museum shows that there are four minor inaccuracies 
as compared to the original machine of 1903, which should be 
remedied, namely : 

(a) The safety flotation tanks should be installed ; 

(b) The fin forward of the dihedral rudder should be removed ; 

(c) The vertical surface at the rear of the dihedral rudder 
should be removed ; and 

(d) The catapult lugs should be fitted to the king post. 

Respectfully submitted, 
Joseph S. Ames, 

Professor of Physics, 

Johns Hopkins University. 
D. W. Taylor, 
Rear Admiral (C. C.) U. S. N., Retired." 

In October, T925, Dr. Walcott directed that the label of 
the large Langley machine of 1903 should be altered to 
read as follows : 

LANGLEY AERODROME 
The Original Langley Flying Machine of 1903. Restored 

IN the opinion of many competent to judge, this was the 
first heavier-than-air craft in the history of the world 

CAPABLE of sustained FREE FLIGHT UNDER ITS OWN POWER. 
carrying a MAN. 

THIS AIRCRAFT SLIGHTLY ANTEDATED THE MACHINE DESIGNED 
AND BUILT BY WILBUR AND ORVILLE WRIGHT, WHICH, ON DECEM- 
BER 17, 1903, WAS THE FIRST IN THE HISTORY OF THE WORLD TO 
ACCOMPLISH SUSTAINED FREE FLIGHT UNDER ITS OWN POWER, 
CARRYING A MAN. 

The aeronautical work of Samuel Pierpont Langley, third Sec- 
retary of the Smithsonian Institution, was begun in 1887. By 
fundamental scientific research he discovered facts, the publication 
of which largely laid the foundation for modern aviation. Langley 
designed large model aeroplanes which repeatedly flew in 1896 
with automatic stability for long distances. The U. S. War De- 
partment, impressed by his success, authorized him to construct a 
man-carrying machine which was completed in the Smithsonian 
shops in the spring of 1903. Attempts made to launch it on October 



NO. 5 SMITHSONIAN INSTITUTION AND WRIGHT BROTHERS 2$ 

7 and December 8, 1903, failed owing to imperfect operation of the 
catapult launching device. In these trials the wings and control 
surfaces were badly damaged and lack of funds prevented other 
tests at that time. The aeroplane was left by the War Department 
with the Smithsonian Institution for further experiments. In 1914 
(following the foundation by the Institution of the Langley Aero- 
dynamical Laboratory) the experiments were resumed, using all 
available parts of the original machine. The frame and engine 
were the same as in the first trials ; the reconstructed wings were 
used without the leading edge extension ; the control surfaces were 
reconstructed ; and launching pontoons with necessary trussing 
were substituted for the original catapult. Thus equipped, and 
weighing over 40 per cent more than in 1903, with Glenn H. Curtiss 
as the pilot, it was successfully flown at Hammondsport, N. Y., 
June 2, 1914. With a more powerful engine and tractor propeller 
it was subsequently flown repeatedly. These tests indicated that 
the original machine would have flown in 1903 had it been success- 
fully launched. After the Hammondsport flights the machine was 
restored in accordance with the original drawings and data under 
the supervision of one of the original mechanics, using all original 
parts available. In 1918 the machine thus restored was deposited 
in the National Museum for permanent exhibition. (Its 52-horse- 
power gasoline engine was designed by Charles M. Manly, who 
superintended the construction of the machine and piloted it in 
1903-) 

THE MODEL AERODROMES DESIGNED BY LANGLEY, THE LANGLEY- 
MANLY ENGINE, AND PHOTOGRAPHS OF THE MACHINES IN FLIGHT 
ARE SHOWN NEARBY. 

6. As regards the sixth point as given on page 3 I do 
not know the basis for Mr. Wright's feeling that the Smith- 
sonian has failed to recognize properly the abilities of him- 
self and his brother as research men. 

The Institution has published two articles, one by Wilbur 
Wright on " Some Aeronautical Experiments " and the 
other by Orville Wright on " Stability of Aeroplanes " (see 
Smithsonian Annual Reports, 1902, pp. 133-148, and 19 14, 
pp. 209-216). Such publication by the Smithsonian Insti- 



26 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

tution is in itself definite recognition of the status of the 
Wrights as discoverers of new truths. 

The Smithsonian Institution has borne charges in which 
have occurred the words " hostile," " insidious," " false 
propaganda," in consequence of the events I have described. 
In order to show that the Institution's officers have not been 
insincere I quote the following passage from a letter which 
I sent to the Editor of the Journal of the Royal Aero- 
nautical Society, April 27, 1928: 

1. Langley himself said after the two unsuccessful launchings 
in 1903: " Failure in the aerodrome itself or its engines there has 
been none ; and it is believed that it is at the moment of success, 
and when the engineering problems have been solved, that a lack 
of means has prevented a continuance of the work." He died in 
the same belief. 

2. Manly twice risked his life in this faith, and eagerly wished to 
risk it thus again. From conversation I had with him in 1925, I 
am certain that he also died in the same belief. 

3. Chanute on several occasions stated that " he had no doubt " 
that Langley's machine " would have flown if it had been well 
launched into the air." 

Such, then, in brief review are statements that have been 
made. In concluding this account, I express, on behalf of 
the Smithsonian Institution, regret : 

1. That any loose or inaccurate statements should 
have been promulgated by it which might be interpreted 
to Mr, Wright's disadvantage. 

2. That it should have contributed by the quotation on 
page 23 of the Smithsonian Annual Report of iQio to 
the impression that the success of the Wright brothers 
was due to anything but their own research, genius, 
sacrifice, and perseverance. 

3. That the experiments of 19 14 should have been con- 
ducted and described in a way to give offense to Mr. 
Orville Wright and his friends. 

I renew to Mr. Wright on behalf of the Smithsonian In- 
stitution, my invitation of March 4, 1928, to deposit for 



NO. 5 SMITHSONIAN INSTITUTION AND WRIGHT BROTHERS 27 

perpetual preservation in the United States National Mu- 
seum the Kitty Hawk plane with which he and his brother 
were the first in history to make successful sustained human 
flight in a power propelled heavier-than-air machine. Fi- 
nally, as a further gesture of good-will, I am willing to let 
Langley's fame rest on its merits, and have directed that 
the labels on the Langley Aerodrome shall be so modified 
k as to tell nothing but facts, without additions of opinion 

as to the accomplishments of Langley. This label now 
reads as follows: 

LANGLEY AERODROME 
THE ORIGINAL SAMUEL PIERPONT LANGLEY 
FLYING MACHINE OF 1903. RESTORED. 

DEPOSITED BY 
THE SMITHSONIAN INSTITUTION 

301,613 



r 



'^,^^ 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOLUME 81, NUMBER 6 



A STUDY OF BODY RADIATION 



BY 
L. B. ALDRIGH 







(Publication 298a) 



DEC 18 1928 

OFFICE LIB^- 



/ 



/■ 



CITY OF WASHINGTON 

PUBLISHED BY THE SMITHSONIAN INSTITUTION 

DECEMBER 1, 1928 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 

VOLUME 81, NUMBER 6 



A STUDY OF BODY RADIATION 



BY 

L. B. ALDRICH 




(Publication 2980) 



CITY OF WASHINGTON 

PUBLISHED BY THE SMITHSONIAN INSTITUTION 

DECEMBER 1, 1928 






Z2>c Bov^ (§aitimon (Prcee 

BALTIMORE, MD., U. S. A. 



A STUDY OF BODY RADIATION 

By L. B. ALDRICH 

CONTENTS PAGE 

Introduction 

Dr. Abbot's experiments in 1921 ^ 

Preliminary experiments in still air 

Preliminary calorimeter experiments ^4 

Calorimeter tests with cloth walls ^ 

Relationship between melikeron and thermoelement results I7 

Experiments on ten subjects in still and in moving air I9 

General discussion 

Summary of results 

Notes on tables 

LIST OF TABLES 

PAGE 
TABLE 

A Abbot-Benedict observations in 1921 -7 

Bi-io. Observations and results of preliminary experiments on ten subjects. 29 

C Observations and results of preliminary calorimeter tests 39 

D Observations and results of calorimeter tests with cloth walls 40 

El-io. Observations and results of experiments on ten subjects in still and m 

41 

movmg air 

F. Summary of cloth-covered calorimeter tests 5i 

G. Summary comparing thermoelement and melikeron 5i 

H. Summary of table E, varying air velocities 5^ 

J. Summary of table E, still air • • • 53 

K. Summary of changes in skin and clothing temperatures in moving air. . 54 

L. Condensed summary of tables B and E 54 

LIST OF TEXT FIGURES 

PAGE 
FIGURE 

1. Melikeron and mounting 4 

2. Thermoelement device 

3. Thermoelement electrical connections 

A Bath for constant temperature junction 9 

10 

5. Calibrating bath 

6. Thermoelement calibration curve 

7. Sketch showing body position numbers ^^ 

8. Vertical and horizontal calorimeters ^5 

9. Diagram for computing solid angle exposed to melikeron 10 

Smithsonian Miscellaneous Collections, Vol. 81, No. 6 ^ 



2 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 51 

INTRODUCTION 

The following is a report submitted to the New York Commission 
on Ventilation, covering experiments conducted by the Smithsonian 
Institution under a grant of $1000 from the Commission. 

The raison d'etre of the experiments here described is explained in 
the following quotation from A Preliminary Note on Radiant Body- 
heat and the School Ventilation Problem, by T. J. Duffield, Execu- 
tive Secretary, New York Commission on Ventilation : 

Satisfactory temperature conditions in the classroom can be established and 
maintained only when the loss of body heat from each pupil is not interfered 
with by similar processes of his neighbors or other bodies. In the class- 
room, the pupil loses heat by evaporation, convection (including conduction), 
and radiation. It is only through thorough consideration of each of these 
types of body heat loss that we can hope to determine logical standards of 
floor and air space per pupil for classrooms. 

The heat required to evaporate the moisture both in the lungs and from 
the body surface is a real loss as far as the pupil is concerned, but the 
heat-loss by evaporation does not enter into the problem of ventilation, because 
the heat has disappeared in the form of latent heat of vaporisation. Modern 
ventilation — using that term in the strict sense — can cope successfully with 
the problem of removing the cowi'ected heat, which, under normal conditions 
of school-room construction and occupancy, is transferred by coMuction to 
the air which surrounds the body. The air, thus heated, expands, rises and 
may be readily removed and replaced by cooler air. In these ways, two of 
the three forms of body heat loss are accomplished, but concerning the third 
form — radiation — very little experimental work appears to have been done 

.... The heat loss by radiation can be cared for only if artificial sources 
of radiant heat in the classroom are properly shielded, and if adequate 
floor space per pupil in the seating section is provided. 

Just what the area of this space should be is a matter requiring further 
study, but, by reason of the different factors affected, it is evident that the 
provision of additional air space by making ceilings higher cannot compensate 
for inadequate floor space. The amount of body heat loss by radiation and 
the thermal gradients for pupils of different average ages must be investigated 
before standards of floor space in classroom design can be established 
scientifically and logically. 

After a conference with Dr. C. G. Abbot. Secretary of the Smith- 
sonian Institution, the New York Commission on A'entilation in June. 
1927, made a grant of $1000 to the Institution to carry out a study 
of body heat loss by radiation. The prosecution of this study was 
delegated by Dr. Abbot to the writer. In a letter dated July 20, 1927. 
Mr. Duffield, Executive Secretary of the New York Commission on 
Ventilation, says : 

Our problems, as we appreciate them are two : 

(i) We want to know the amount of body heat loss by radiation and its 
relation to the total under various conditions of air temperature, and if they 



NO. 6 BODY RADIATION ALDRICH 3 

would have any influence under varying conditions of humidity and air 
motion as well. Of course we are primarily interested in this as it affects the 
normally clothed school child, but I feel that this study should be extended 
to include adults as well, in order that we may make a definite contribution 
to our knowledge concerning the relative importance of the different types 
of heat loss under varying external conditions. 

(2) We are greatly interested in the' thermal heat gradients about pupils 
normally clothed under conditions prevailing in the school rooms where the 
average pupil is surrounded by his radiant neighbors, distance from him 20 
to 24 inches. This matter should be studied at various temperatures ranging 
fiom 60° to 70° F. and if the findings of the first study warrant it, under 
various conditions of humidity and rates of air change as well. 

As a preliminary, in order to discover what criteria govern the 
spacing of children in classrooms, the following letter, signed by the 
Acting Secretary of the Smithsonian Institution, was sent in August, 
1927, to the superintendents of schools in ten of the larger cities of the 
United States : 

At the suggestion of the New York Commission on Ventilation, the Smith- 
sonian Institution is conducting a research concerning the amount of body 
heat loss by radiation, particularly as it affects children in the classroom. 

As an aid to this research, the Institution would greatly appreciate your 
kindness in replying to the following three queries : 

(1) In the schools under your supervision, what considerations were factors 
in establishing the space allotted to each individual in the classrooms? 

(2) In particular, was any consideration given to the loss of heat by radia- 
tion from the individual pupils ? 

(3) Are the radiators or other artificial heat sources in classrooms shielded 
to prevent direct radiation to the pupils ? 

Your cooperation is earnestly hoped for. 

Seven replies were received. To question (i), all seven answered 
that the classrooms were of certain standard sizes, determined gener- 
ally by state law. To question (2), all seven replied no. To ques- 
tion (3), six answered no and one yes. This correspondence makes 
it evident that as yet the question of radiation exchange between 
pupils and surrounding objects has been given practically no consid- 
eration in designing classrooms. 

DR. ABBOT'S EXPERIMENTS IN 1921 

In the spring of 1921, Dr. Abbot conducted a series of experiments 
on the radiation from the nude body. This work was carried out at 
the invitation of Dr. F. G. Benedict in the Nutrition Laboratory of 
the Carnegie Institution in Boston. A description of this work and 
summary of Dr. Abbot's results, since they have not been previously 
published, are with his permission incorporated here. 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 



In 1920 the Smithsonian Astrophysical Observatory designed and 
built a new instrument for the measurement of radiation called the 
" melikeron." It is essentially different from the ordinary type of 
radiation instrument such as the pyranometer, pyrgeometer, bolome- 
ter, etc., in that radiation is absorbed not upon a flat surface but by 
a device shaped like a honeycomb. This makes the melikeron, by vir- 
tue of its form, approximately a " black body," capable of absorbing 
practically all radiation falling upon it. A detailed description of the 
instrument and tests made upon it are given in Smithsonian Miscel- 




;^XX\X^-^^\\^\^NX^ 



Fig. I. — Melikeron and mounting, showing special water-circulating vesti- 
bule and water-circulating, " pin-cushion " shutter. 



W — Wooden insulator. 
M — Melikeron. 
5^— Shutter. 
H — Honeycomb absorber. 



D — Metal diaphragms. 
C— Circulating water. 
F — Blackened metal points. 



laneous Collections, Vol. '/2, No. 13. Being well adapted to the mea- 
surement of long wave radiation such as is emitted by bodies at low- 
temperature, Melikeron No. i was chosen by Dr. Abbot for his mea- 
surements on the radiation from a nude subject in Dr. Benedict's 
laboratory. A special mounting was made, with the melikeron en- 
closed in a wooden case to keep air currents away. The front was 
provided with a diaphragmed vestibule through which water circu- 



NO. 6 BODY RADIATION ALDRICH 5 

lated. The diaphragms helped to prevent convection currents from 
reaching the honeycomb and also limited the radiation received to a 
known solid angle. A water circulating shutter completed the mount- 
ing. The side of the shutter exposed to the melikeron consisted of a 
large number of projecting metallic points and resembled a "pin- 
cushion." This made the shutter as well as the melikeron an approxi- 
mately " black body " by virtue of its form. The vestibule and shut- 
ter are shown in cross-section in figure i. 

The melikeron and mounting were securely clamped to the round 
of a chair back. Observations were made upon the nude subject 
standing or sitting before the instrument so that the skin was about 
15 mm. from the shutter. Direct skin temperature measurements 
were made at the same positions and as nearly as possible at the same 
time by Dr. Benedict, using his rubber-backed thermoelement device 
described in his paper. " The temperature of the human skin " (Asher- 
Spiro's Ergebnisse der Physiologic. Supplement-Band, 1925). 

To abstract from Dr. Abbot's notes — 

Suppose the temperature of the " pin-cushion " shutter is 
To = 273-Ffo- Its radiation is o-ro* = 8.20X IQ-^^X (2734-/0)* in small 
calories per sq. cm. per minute (Stefan-Boltzmann formula, see 
Smithsonian Physical Tables, p. 247). This applies to radiation to a 
whole hemisphere. The jacket surrounding the melikeron limits the 
radiation to a circular opening 3.66 cm. in diameter and 7.03 cm. 
from the absorbing surface of the melikeron. It is necessary to deter- 
mine what part of the total radiation from a whole hemisphere enters 
through this opening. See figure 9. 

Let O be the center of the absorbing surface of the melikeron, and 
AB the opening in the jacket. Then the area of the opening AB 
will be 

(27rp sin 0)pd6 



and the radiation received on the horizontal surface at O will be pro- 
portional to 

iTTp sin OpdB cos 6 



[6 

= 27rp- sin 6 cos Odd = vp- sm" 



For the whole hemisphere this becomes -n-p- 

The part of the total radiation entering" the vestibule is the ratio 

irp'^ sin^ .0/1 
— e — =:sm- 6 



6 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

For diameter 3.66 cm. and fj'=^y.o^ cm., 

(1.8^)2 

Note. — In certain experiments on the hand (see Table A) a smaller open- 
ing was used having diameter 2.42 cm. For this, sin^ d = .02877. 

The paper referred to above (Smithsonian Misc. Coll., Vol. 72, 
No. 13) gives the constant of melikeron No. i as 2.45. That is, by 
multiplying 2.45 by the square of the current, in amperes, required to 
compensate, we obtain, in calories per sq. cm. per minute, the differ- 
ence in radiation between the shutter and whatever object is exposed 
on removing the shutter. The difference in radiation between the 
" i)in-cushion " shutter and the skin would be 

A shunted voltmeter of 49.3 ohms resistance was used to measure 
the current, hence 

2.45 V^ _ .g oioqSF^ 
(49-3)^ sin^^ " s'm^ 
where [^' = voltmeter reading in volts. 

The shutter being a black body at temperature to C., radiates 

8.20+10-1^(273 + /,,)* 

Then the skin radiates 

8.20 X 10-" (273 + to)* + .001008 gjj^ 

if we neglect the radiation which appears to arise in the skin, but 
really is reflected by the skin into the instrument and was emitted by 
the walls of the room, the vestibule of the melikeron, and so forth. 
If the skin was a perfect radiator or " black body " this reflection 
correction would be zero. 

We may get a line on this by computing the temperature of the 
skin, assuming it " black " and comparing with observed tempera- 
tures taken directly. 

If Ti = absolute temperature of skin 

To = absolute temperature of pin-cushion shutter, 

Skin radiation =:orTi* 
Shutter radiation ~ aTo* 

Then i?=. 001 008 ~J^ =a(T,'-To^) 
sui- 6 ^ ^ 

T,' = To' + .001008^^^ =To'+ 1.939V' X 10' 



NO. 6 BODY RADIATION ALDRICH 7 

for the large aperture and, 

= To* + 4.27V- xio"" 
for the small aperture. 

The observations and computed temperatures are recorded in 
table A. The part of the body exposed to the melikeron is shown in 
the table by the position number. Interpretation of these numbers is 
given in figure 7. 

As explained on page 8 of the paper on the melikeron, a check on 
the ability of Melikeron No. i to absorb completely low temperature 
radiation was made. The mean result of the test yielded a value for 
the constant 

(T = 8.49X io~^^ 

Again in April, 1921, after returning from the Boston work. 
Dr. Abbot made a similar test. The mean of 3 values gave 

o- = 8.58xio-" 

These values would tend to show that the constant 2.45 for Melikeron 
No. I is perhaps a little too high. 

PRELIMINARY EXPERIMENTS IN STILL AIR 

In the preceding we have described experiments by Drs. Abbot 
and Benedict in Boston in 1921. All the subsequent experiments de- 
scribed in this report were performed by the writer at the Smith- 
sonian Institution in Washington. The first series of experiments 
was more or less preliminary in nature. They were carried out in the 
large laboratory room of the Astrophysical Observatory under some- 
what unsatisfactory conditions as regards the control of wall and 
room temperatures. 

As in the Abbot-Benedict work, two instruments, one for the direct 
measurement of radiation, and one for measurement of surface tem- 
peratures were used. Melikeron No. 2 replaced No. i previously used, 
but the same water circulating vestibule and " pin-cushion " shutter 
were retained. On November 28, 1927, a test of Melikeron No. 2 
was made, as had been done for No. i, by exposing to a black body 
at a known low temperature. Five determinations gave the following 
values for a 

8.ro X 10" 

8.23 

8.23 

8.42 

8.84 



Mean 8.36 X 10" 



8 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 



The melikeron was clamped in a vertical position at a convenient 
height (about i m.) and remained unchanged throughout the work. 
The subject stood or sat in front of the instrument so that the part 
of skin or clothing exposed was al)0ut 5 to lo cm. from the shutter. 
In the first trials, water directly from the tap was circulated through 
vestibule and shutter. The difiference in temperature, however, be- 
tween the surrounding air and the shutter and vestibule produced a 




Fig. 2. — Thermoelement device for measuring surface temperatures. 



F — Fibre rings. 
S- — German silver frame. 
]V — Wooden handle. 



P — Spring steel projection 
[/—Silk thread. 
T — Thermoelement. 



Cu ^ 




Fig. 3. — Diagram of electrical connections of copper-nickel thermoelement. 

G — Galvanometer. 

T — Thermoelement junction. 

C — Constant temperature junction. 

convection effect which altered as the shutter opened and closed and 
introduced an error resulting in too large values. Fifty feet of block 
tin pipe was then coiled and placed in a tank of water kept at room 
temperature. The tap water passed through this just before entering 
the instrument. Mercury thermometers measured the temperature of 



NO. 6 



BODY RADIATION ALDRICH 



the circulating water before entering the vestibule and after leaving 
the shutter. The mean was used as the shutter temperature. 

For the direct measurement of skin and clothing temperatures, a 
special device was prepared with the help of Mr. Kramer, the Ob- 
servatory mechanician, and embodying Dr. Abbot's suggestions. The 
device is shown in figure 2. It consists of a specially mounted copper- 
nickel thermoelement of fine drawn wire. A frame of German silver 
is bent as shown in the figure and fastened in a wooden handle, W. 
Two silk threads are stretched to form a cross between the four 
spring-wire posts, p. The thermoelement wires are fastened sym- 




FiG. 4. — Bath for constant temperature junction. 

Th — Thermometer. 
D — Stirring device. 
A'. — Kerosene bath. 
V — Vacuum flask. 

metrically to these silk threads with the junction straddling the length- 
wise thread. The wires lead out through fibre rings, F, and through 
the wooden handle. The copper wire (see fig. 3) leads through a 
switch to a sensitive type Leeds and Northrup D'Arsonval gal- 
vanometer and thence to the constant temperature junction in a stirred 
kerosene bath as shown in figure 4. The Cu-Ni wires are sufficiently 



lO 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 



long SO that all desired positions can be reached without moving the 
constant temperature bath. Holding the device by the wooden handle, 
one presses lightly the four prongs of spring wire p upon the surface 
whose temperature is desired. This places the junction in excellent 
contact with the surface. There is no backing to the junction save a 
single silk thread, and thus no possibility of heat piling up and caus- 
ing too high temperatures. For about |- cm. on each side of the junc- 




FiG. 5. — Calibrating bath. 

/ — Thermoelement device. 
B — Insulation of cotton batting. 

tion, the wire also touches the surface and assumes the surface tem- 
perature, thus eliminating error due to cooling of the junction by 
conduction along the wires. 

Instead of a potentiometer for measuring microvolts, the thermo- 
element was calibrated by plotting galvanometer deflections directly 
against temperature differences between the two junctions. A kero- 
sene bath (fig. 5) was prepared in which the thermoelement device 



NO. 6 



BODY RADIATION ALDRICH 



II 



was immersed. By a series of changes of the temperatures of both 
baths a plot (fig. 6) of the relationship between galvanometer deflec- 
tion and temperature difference was made. By carefully keeping the 
whole set-up— galvanometer, scale distance, electrical resistance and 



\ 








24 








1 










20 














\ 






16 




o oo 


DEC, 15, 
MAR. 28, 
JULY 26, 


1927 
1928 
1928 






— ^ 


\ 




12 












2 

o 




\ 


\ 


8 












00 

o 






\ 


V A 












o 

UJ 

—1 

iL. 

UJ 

o 








\ 












> 

-J 

< 

CD 


e 


6 


4 


2 "<! 

-4- 


v 


2 + 


4 + 


6 -^ 


6 










-6 


\ 


\ 
















-12 




\ 


^. 














-le 






\ 














-2C 








\ 








DE 


.GREE5 


C.-2. 


} 






~^ 


\ 


1 
















^\ 



Fic, 6.— Thermoelement calibration curve. 

contacts, etc.— unchanged, negligible change was found in the cali- 
bration curves made at the beginning, during and at the end of the 
experiments. It is probable that the calibration curve is accurate to 
o°.i C. To avoid error from lack of uniformity of the galvanometer 



12 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 



scale, the zero of the galvanometer was always kept exactly at the 
middle of the scale. 

Ten subjects were chosen. 3 adults and 7 children. Each subject 
wore ordinary clothing. No attempt was made to minimize metabol- 
ism, either bv rest or diet before the measurements. The subject stood 
or sat, exposing to the melikeron in succession some to different places 




LEFT 




BACK 
7.— Sketch showing l)ody position numbers. 

on the body, usually 3 places on the exposed skin, i on the hair, 
I on the shoes, and 5 on the clothed parts. Figure 7, adapted from 
a similar figure kindly furnished by Dr. Benedict, gives a series of 
numbers corresponding to definite places measured. A single meli- 
keron measurement required from 5 to 10 minutes, for the instrument 
is sluggish and requires careful adjustment of the compensating 
current. Immediately following each melikeron measurement the 
skin temperature was determined with the thermoelement device upon 



NO. 6 BODY RADIATION ALDRICH 1 3 

the same part of the skin or clothing. Usually 3 independent mea- 
sures of the temperature were made, since each required less than 
^ minute, and the mean used. 

The observations are summarized in table B. The application of 
the Stefan formula to obtain the computed temperatures was the 
same as described under the Abbot-Benedict experiments, except 
that for Melikeron No. 2 the constants are altered. 

Thus (see fig. 9, also pages 5 to 6), 

R = a(T^*- To') sm' 6 
where 

Rz= ( constant Melik. No. 2) x C" 

= 4.0X (current in amperes)- 
o-= 8.20X10"" 
Ti = absolute temperature of radiator 
To = al)solute temperature of melikeron shutter 
■ '^ n '" ''' (1-83)' r r 

Tben T/=ro^+ 8:^ x:26x IQ-" =^"^ + ^-^5C-X 10" 

From this equation, the value of T"i, the absolute temperature of the 
surface measured, is determined. 

In examining tal)les A and B, we find that the 4th power formula 
appHed to the measurements on either skin or clothing yields values 
as great or slightly greater than the observed temperatures. This is 
evidence that the skin and clothing radiate as a black body at the low 
temperatures measured. Cobet and Bramigk (Ueber Messung der 
Warmestialung der menschlichen Haut und ihre klinische Bedeutung, 
Deutsches Archiv fiir klinische Medizin, Vol. 144, p. 45 to 60) con- 
firm this result on the skin, and Leonard Hill (The Science of Ven- 
tilation and Open Air Treatment, British Govt. Report, 1919, Medi- 
cal Research Commission) finds both skin and clothing nearly black- 
body radiators for low temperature radiation. 

In table B, the values in the Radiation Summary were o1)tained Ijy 
the application of Stefan's formula to the mean temperatures given 
under Temp. Summary. For example, in table Bi, we have given 

Estimated wall temp. = 21 °o 
Mean skin tem]x =33?^ 



Then 



= 8.2oxio^"r(273 + 33.7)'- (273 + 21.0)^1 
= .1131 calories per sq. cm. per minute. 



14 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

The value of the Total Radiation of the subject is obtained some- 
what empirically as follows: The total surface area (see Notes on 
Tables, p. 26) is divided into sections 

skin area, girls 8%, boys 7% 

hair 5% 

clothing, girls 78%, boys 79% 

shoes 9% (if boots, 10% and clothing 78%) 

The average skin radiation per sq. cm., as just determined, is mul- 
tiplied by the corresponding number of centimeters of exposed skin, 
and similarly for clothing, hair, and shoe areas, and the sum taken. 
Since part of this total is ineffective, due to the area between the legs 
and under the arms not radiating to a full hemisphere of wall, this 
total radiation is reduced 8%. Dividing this result by the number of 
sq. m. surface area gives the value recorded under Total Radiation. 

PRELIMINARY CALORIMETER EXPERIMENTS 

The total radiation values of table B appeared much too large when 
compared with the basal metabolism values. The total energy pro- 
duction or metabolism must at all times equal the total energy loss. 
Exclusive of a small loss through urine and faeces and the warming 
of air and food taken in, there are three ways in which the body loses 
heat, namely, by radiation, by convection (including conduction), and 
by evaporation of water from lungs and skin. Du Bois states (Basal 
Metabolism in Health and Disease, ed. 1927, p. 400) that for a room 
temperature 22° to 25° C. and relative humidity 30 to 50%, the loss 
by vaporization of water from lungs and skin is about 24% of the 
total loss. By analogy with work done on the cooling of wires and 
blackened spheres we would expect the body convection loss to be at 
least as great as the radiation loss. For example, on p. 251, Smith- 
sonian Physical Tables, 7th Ed., McFarlane finds the total loss of 
least as great as the radiation loss. For example, on p. 251, Smith- 
to a blackened enclosure at 14'^ is .00266 gram calories per second, or 
.1596 calories per minute. On page 247 the difference in radiation 
between a black body at 24° C. and one at 14° is 918 — 801 = 117 
gram cal. per sq. cm. per 24 hours or .0813 calories per sq. cm. per 
minute. 

Then the per cent of radiation loss of the blackened sphere (which, 
to be sure, at these low temperatures radiates decidedly less than the 
" black body ") is 

.0813 ^ . , ^ 

- ^ = 51%, convection loss = 497to 

It is of course true that the actual energy production of each of the 
ten subjects was materially greater than that shown by the basal 



NO. 6 



BODY RADIATION ALDRICH 



15 



metabolism values. Yet even when adequate allowance is made for 
this, the radiation loss seemed to be an unexpectedly large proportion 
of the total energy production. 

After conference with Dr. Abbot and several members of the 
New York Commission on Ventilation, a series of experiments was 
started with the hope of shedding some light on the amount of body 
convection loss. These experiments proved that convection was, in- 
deed, less than had been anticipated, but the close approach of total 
radiation to basal metabolism remains surprising. 





^^ 




HeRIZONTAL 



VERTICAL 
Fir 8— Cylindrical copper calorimeters, each 38 cm long and 30.5 cm. 
diameter," fiUed with water^a'nd completely covered with tight fittmg jackets con- 
sisting of one thickness of brown canton-flannel cloth. 
A — Thermometer. 
B — Stirring device. • 

C— Electrical heating element. 

Two calorimeters were prepared of thin sheet copper, cylindrical 
in shape, each 38 cm. long by 30.5 cm. in diameter. One was 
mounted vertically and the other horizontally, each supported on 
four rubber blocks on the top of four metal rods. This permitted 
free convection and radiation on all sides but the rate of cooling 
of the vertical calorimeter might well be less than that of the 
horizontal because the warm convection currents rising from be- 
low would more closelv l)athe the sides in the vertical form. Appro- 
priate stirring and heating devices were inserted as shown m 
figure 8. Each was filled with a known amount of water, and the 



i6 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOL. 



outside completely covered with a tight fitting jacket consisting of 
a single thickness of brown canton-flannel cloth. The purpose of 
the shape and covering of the calorimeters was to simulate the 
clothed human body. Heat was lost from the calorimeter only by 
radiation and convection, and the total loss of heat per hour could 
be accurately determined from the rate of change in temperature of 
the water and the water equivalent of the calorimeter. A series of 
tests was made with each calorimeter, and in each test the radiation 
loss was determined with the melikeron and with the thermoelement, 
following exactly the method described above as applied to human 
subjects. 







Fig. 9. — Diagram for coinputing solid angle exposed to melikeron. 

The results of the preliminary tests are given in table C. Several 
interesting points appear. First, the radiation loss of the horizontal 
calorimeter is 6 or 7% less than in the vertical. This indicates that 
the shape of the calorimeter is important in determining the amount 
of the convection and helps to account for the difference in convection 
between the sphere 50% and the cylinders 70 to 80%. As noted above, 
however, this discrepancy is also in part due to the less perfect radiat- 
ing properties of lamp-black than of porous cloth. Second, in the test 
of March 3, with air motion of about 300 feet per minute the radia- 
tion is only 47% and the convection increased to 53%. Third, with 
no cloth cover, the test of March 26 shows only 34% radiated from 
the copper surface in still air. This is an indication of the low emis- 
sivity of the metal surface as compared with the cloth. 



CALORIMETER TESTS WITH CLOTH WALLS 

A weakness in the experiments thus far has been the impossibility 
of accurately knowing the mean temperature of the walls to which 
the subjects or calorimeters are radiating. A very helpful letter from 
Prof. Phelps of the New York Commission dated March 27, 1928. 
suggested the possibility of standardizing the wall conditions by sur- 
rounding the subject with cloth draperies whose temperature, closely 
that of the air in the room, could be determined with the same thermo- 



NO. 6 BODY RADIATION ALDRICH 1 7 

element used on the subject. This suggestion seemed especially feasi- 
ble since our results indicate that cloth radiates nearly as a black body. 
Accordingly, brown canton-flannel cloth was hung forming a cur- 
tained room 2^ meters high and li by 2 meters in area, enclosing the 
calorimeter and with the melikeron mounting projecting through the 
curtain. The same cloth also formed the ceiling and floor. For part 
of the tests a current of air of known velocity from an electric fan 
outside the curtain was admitted through a hole in the cloth. The air 
velocity at the calorimeter was measured with a Katathermometer, 
an instrument invented by Prof. Leonard Hill, of England (see The 
Science of Ventilation and Open Air Treatment, British Govt. Report, 
1919). and serving admirably for this purpose. The motor of the 
electric fan was run on storage batteries to insure a more constant 
air current. The Katathermometer was kindly furnished by Mr. 
Dufifield, of the New York Commission. 

The results of these tests are found in table D. Table F is a con- 
densed summary of both tables C and D. From these tables a num- 
ber of conclusions can be drawn : 

(i) The amount radiated from the horizontal cylindrical calori- 
meter is about 7% less than from the vertical cylindrical calorimeter. 

(2) The estimated wall temperatures in the preliminary calori- 
meter experiments are too low. From this cause the amount radiated 
should probably be lowered at least 10%. Much more weight can be 
placed in the measured wall temperatures of the cloth walls. 

(3) For air motions greater than 75 feet per minute, the melikeron 
is unsatisfactory for use. An irregular drift of the galvanometer zero 
due probably to small fluctuating convection currents makes the in- 
strument unreliable. 

(4) In the ]>reliminai-y experiments the melikeron gives appre- 
ciably higher results than the thermoelement, and in the second set 
of experiments this discrepancy disappears. The cause of this is 
explained in the following section. 

RELATIONSHIP BETWEEN MELIKERON AND THERMO- 
ELEMENT RESULTS 

In the preceding experiments, recorded in tables B, C, D and E, 
we have 265 comparisons of temperatures determined directly by 
thermoelement and computed from the radiation as measured with 
the melikeron, and including skin, clothing, hair, shoes, wall, and 
cloth-covered calorimeter temperatures. By a study of these com- 
parisons we can determine their relationship, with a view to using 
only the thermoelement in a new series of experiments. The thermo- 



l8 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

element is much quicker and easier to use than the meHkeron. Also 
it offers no difficulty in air currents where the melikeron becomes 
unusable. 

Table G is a summary of this kind. The first trials with the water 
jacketed melikeron indicated a minus correction (see page 8) when 
the water jacket temperature was less than room temperature. The 
water jacket temperatures are therefore given in all the tables and 
the differences Room Temperature minus Water Jacket Tempera- 
ture are recorded in table G. Examination discloses a rough equality 
between the differences Melikeron minus Thermoelement and Room 
Temperature minus Water Jacket Temperature. In the wall tem- 
peratures no difference is noted between melikeron and thermo- 
element — which is as we might expect since the wall is always close 
to room temperature, and the melikeron reading is very small. In the 
measurements at air velocities greater than 130 feet per minute there 
is decided disagreement — which we know is due to the unsatisfactory 
performance of the melikeron in air currents. Of the remaining ob- 
servations, the difference Melikeron minus Thermoelement on the 
skin is much larger than in any other group. For comparison, all the 
other groups, viz., clothing, hair, shoes, and calorimeter, are united in 
one group at the bottom. From the algebraic mean of Room T. minus 
Water J. T. in this group. 

when Room T. minus Water J. T. = ?82, Melik. minus Therm. = ?8o 
that is, the melikeron calculated temperature is in error by as much 
as the water jacket differs in temperature from the wall. Hence we 
may conclude that on the skin, when Room T. — Water J. T. = o, 

Melik.— Therm. = I Tqi - o°67 = I °24. 

Again from the arithmetical mean of Room T. — Water J. T., 

when Room T.— Water J. T.= i?i4, Mehk.— Therm. = °8o 

from which on the skin, when Room T. — Water J. T. = o, 

Melik.— Therm. = I foi- ^^ x°8o=i?oo 

1. 14 

A mean of all clothing, hair, shoes, and calorimeter (Melik. — Therm.) 
differences whose (Room T. — Water J. T.) differences are less than 
ifo gives 

No. of Melik-.— therm. Room T.— water J. T. 

observations difference difference (algebraic) 

30 °Si °39 

Calorimeter tests alone give 

8 .20 .24 



NO. 6 BODY RADIATION ALDRICH I9 

These results confirm the preceding conchision that the meHkeron 
computed temperatures are in error by just as much as the water 
jacket differs in temperature from the wall. Summarizing the above 
evidence, it appears that when the Room T. minus the Water J. T. 
is zero, the Melikeron and Thermoelement temperatures on clothing, 
hair, shoes, and calorimeter agree with each other within °i. On the 
skin, however, when the Room T. minus the Water J. T. is zero the 
melikeron computed temperatures are approximately i?i greater than 
the thermoelement temperatures. Dr. Abbot's skin measurements of 
1921 at Boston (see table A) give evidence of the same thing — that 
on the skin the melikeron computed temperatures are higher than 
those measured directly with the thermoelement. A mean of 53 of his 
values in table A gives 

Melikeron minus Thermoelement = i°9 

As an explanation for the persistently larger melikeron temperatures 
on the skin, Dr. Abbot suggests that since the skin is porous and the 
internal temperature of the body is higher than that of the surface, the 
melikeron sees into a deeper layer than that reached by the thermo- 
element. 

EXPERIMENTS ON TEN SUBJECTS IN STILL 
AND IN MOVING AIR 

A second series of experiments on human subjects was begun on 
May 30, 1928. It included 8 children of school age and 2 adults. 
Three similar sets of observations were taken on each subject, first 
in still air, second with moderate air motion, and third with faster air 
motion. As before, the air motion was produced by an electric fan 
three meters away, the motor of which ran on storage batteries. Air 
velocities wefe again measured with the Hill Katathermometer. Each 
subject was placed inside the same curtained room described under 
the calorimeter experiments. Skin, clothing and wall temperatures 
were measured with the thermoelement device. Exactly the same 
body and wall positions were measured on each subject. A complete 
set included 7 observations on the exposed skin, 15 on the clothing, 
I on the hair, 2 on the shoes, and 10 on the walls. The skin tempera- 
tures were then corrected to the melikeron scale by increasing the 
thermoelement skin temperatures i°i as explained in the previous 
section. The observations were grouped and summarized as shown 
in table E. Following exactly the method described on page 13, 
Stefan's 4th power formula was applied to the various groups and 
values of the total radiation determined as g^iven in table E. 



20 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

Unlike the first series of experiments on lo subjects (see table B), 
this second series was carried out in midsummer. Fortunately the 
room was equipped with refrigerating pipes so that the room tem- 
peratures were kept fairly normal and comfortable. These pipes were 
entirely outside of the curtained room where experiments were made. 

Attention is called to the summaries of table E data contained in 
tables H, J and K. Table H divides the air velocities into four groups 
and shows how, with the room and wall temperatures remaining 
nearly constant, the calories of radiation loss progressively decrease 
as the air motion mcreases. Table J gives for each subject, in calories 
per sq. m. of body surface, the basal meiabolism and the loss of heat 
by radiation ; also the ratios between these two cjuantities. These 
ratios are also arranged according to increasing room temperatures. 
A marked decrease in the ratio occurs with increasing room (and 
with it the wall) temperatures. Table K is a summary showing the 
changes in skin and clothing temperatures with varying air velocities, 
dividing the changes into three groups, namely, temperature changes 
on the side of the subject toward the fan, perpendicular to it, and 
away from it. A drop in temperature occurs in all three groups, with 
the greatest drop on the side toward the fan. In the other two groups 
the drop is only about one half as great. On the side towards the fan 
the clothing temperature drop is about one third greater than the skin 
temperature drop. 

GENERAL DISCUSSION 

We have presented the results of three series of experiments on the 
radiation loss of human subjects, and a fourth series on the radiation 
loss from specially prepared calorimeters. The first series gave the 
results of Drs. Abbot and Benedict on the radiation and skin tempera- 
tures of a nude subject when the room temperature was held at 15° 
and again when it was held at 26°. It is interesting to note the change 
in radiation loss in these two different cases. On March 31, when the 
room temperature was 15°, the thermoelement skin temperature 
(mean of 87 values, many of which are not included in table A) was 
27^2, and on April i, when the room temperature was 26°o (mean of 
40 values), was 30°8. The black body temperatures, computed from 
the melikeron values and the Stefan formula, were March 31 (mean 
of 20 values) 28'^2, and on April i (mean of 12 values) 33°4. 
Dr. Benedict estimated the wall temperature on April i to be 26°, and 
it is probable that on Alarch 31 the wall temperature was at least as 
low as 15°. (Outside temperature was 8°6.) Assuming these wall 



NO. 6 BODY RADIATION ALDRICH 21 

temperatures we can compute from the Stefan formula the average 
radiation per sq. cm. per minute from the body. It results as follows : 

March 31, from thermoelement, .1003 cal., from melikeron, .1109 cal. 
April I, from thermoelement, .0432 cal., from melikeron, .0673 cal. 

Thus the body actually radiated in the order of twice as much when 
the walls were at 15° as when the walls were at 26°. The best work 
in basal metabolism indicates that an individual's metabolism remains 
practically unchanged through this range of room temperature. A 
very considerable readjustment, perhaps of water vapor loss, must 
take place to compensate for the large change in radiation. 

Let us compare the two series of experiments on human subjects 
recorded in tables B and E. Each series included 10 individual sub- 
jects, composed of adults and children of school age, of both sexes and 
all normally clothed. The first series was performed in midwinter, 
the second series in midsummer. During the first, the mean relative 
humidity was 43% and during the second 62%. In each series de- 
terminations were made on each subject of the total loss of heat by 
radiation in still air. The second of the two series deserves greater 
weight for two reasons : 

(i) Cloth walls were used and the mean wall temperature deter- 
mined from actual measurements with the thermoelement. 

(2) A greater number of skin and clothing temperatures were 
measured since only the thermoelement was used. 

In the first series the subject radiated to the walls, windows, and 
furniture of the room. Their mean temperature was estimated from 
the room temperature, after a study, on a typical day, of the relation- 
ship between the room temperature and that of the walls, windows, 
and furniture. From this study it was concluded that the mean wall 
temperature was probably ?5 below room temperature. Ibis arbi- 
trary correction was adopted for all the preliminary 10 subjects and 
also for the preliminary calorimeter experiments (see table C). It is 
remarked on page 17 under (2) that the estimated wall temperatures 
in the table C data are probably too low. The reason for this can 
be seen from the fact that the table C data were obtained' in the 
spring, whereas the table B data were taken in midwinter. The mean 
outside temperature was ii?o for table C, and 3°5 for table B. It is 
evident that with a warmer temperature outside, the °5 difiference 
between room and wall temperature was too great. On the other 
hand, on examining the data of the typical day from which the arbi- 
trary °5 correction was determined, I find that the outside tempera- 
ture was 2° and that the mean wall temperature was in reality i°o 
below room temperature. The arbitrary correction was made "5 



22 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

because 1 erroneously thought the mean outside temperature was 
considerably above 2? It is probable then that since the mean out- 
side temperature was actually only i°5 above that of the measured 
day, the wall temperatures of table B should have been several tenths 
degree lower. As explained on pages 18 to 19, there is also another 
correction to be made in table B, due to the difference Room Temp. — 
Water Jacket Temp. This correction requires a lowering of the skin 
and clothing temperatures of about the same magnitude as the wall 
temperature correction just mentioned. It is a fortunate accident that 
the dift'erence in temperature between the body surface and the walls 
thus remains nearly the same and the mean radiation values in table B 
remain unchanged. 

Table L compares the means of the two series, tables B and E. 
The total radiation is greater in the first series due to the lower mean 
room temperature. The adult basal metabolism (determined from 
Du Bois' chart) is higher in the first series because the 3 adults were 
two male and one female, average age 31, whereas in the second 
series the adults were both female and average age 43. The work 
of many investigators agrees in placing the basal metabolism per 
sq. m. of body surface of adults considerably lower than that of chil- 
dren. Yet the radiation losses in tables B and E show no such change 
as between adults and children. In table L the ratios 

Radiation loss 



Basal metabolism 
are in each case higher for adults than children. This is difficult to 
explain. 

At normal indoor temperatures, in still air and with the subject 
normally clothed and at rest, the major heat losses would be dis- 
tributed as follows : The loss by evaporation of water from lungs and 
skin (as stated by Du Bois, see page 14) is 24% of the total. The 
convection loss, assuming it is similar to that of the cloth-covered 
vertical calorimeter, is f of the radiation loss. Or, 

Water vapor loss = 24% of the total 
Radiation loss =46% of the total 

Convection loss = 30% of the total 

It is interesting to compare this with a statement by Rubner (see 
page 20, Leonard Hill, The Science of Ventilation and Open Air 
Treatment) that " for an average man, in still air, the loss of heat 
is distributed as follows : Warming of inspired air, 35 ; warming 
the food, 42 ; evaporation of water, 55S ; convection loss, 823 ; radia- 
tion, ii8t ; total loss, 2700 kg. calories." 



NO. 



BODY RADIATION ALDRICH 23 



111 considering the method by which the total radiation values are 
obtained in these experiments, there will perhaps be question con- 
cerning the correctness of the empirical division of the body surface 
into skin, clothing, shoe, and hair areas, as well as the 8% reduction 
for ineffective radiation between legs and under arms. Yet these 
factors may be altered through a considerable range and not materi- 
ally alter the final result. The radiation loss will still be nearly the 
same magnitude. 

It has been a matter of surprise to the writer that the literature 
covering calorimetry experiments on the total energy consumption 
of human subjects makes so little mention of the surrounding tem- 
peratures to which the subject radiates ; also that in the comparisons 
between direct and indirect calorimetry the temperatures used are 
nearly the same throughout. It was my privilege on March 21, 1928, 
accompanied by Prof. Phelps, of the New York Commission, to visit 
the Bellevue Hospital laboratory of Dr. Du Bois, to talk with him and 
see the operation of the Sage calorimeter which, under the skilful 
manipulation of Dr. Du Bois and his assistants, has added a new chap- 
ter to our knowledge of metabolism in health and disease. The visit 
was of especial interest in that Dr. Stefansson, the explorer, was pres- 
ent for a metabolism test to determine the effect of an exclusively meat 
diet. Dr. Du Bois explained that the reason all his experiments had 
been carried out at nearly the same temperature was because of the in- 
tricacy of the apparatus and the difficulty of redetermining all the con- 
stants for each set of temperatures. He agreed that it was important 
to compare direct and indirect calorimetry at other temperatures and 
indicated that he hoped to find opportunity to do so. 

Incidentally in the course of these experiments, rough tests were 
made with the thermoelement device to see how rapidly its tempera- 
ture falls off as the thermoelement recedes from the skin or clothing. 
The thermoelement has a bright metal surface and consequently its 
temperature is but little affected by absorption of radiation. The tests 
show that, in moving the device horizontally away from the body, 
as soon as actual contact is broken between thermoelement and skin 
or clothing, the thermoelement temperature falls rapidly almost to 
room temperature and then gradually declines to room temperature 
as the thermoelement recedes. At 30 cm. distance no effect of the 
presence of the body could be detected in still air. There would be a 
marked effect of course if the thermoelement were held over the 
body instead of at the side, or if the thermoelement had a better 
emissivity so that its temperature would be raised by a larger ab- 
sorption of radiation. 



24 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

SUMMARY OF RESULTS. 

The concrete results of these experiments are brietiy summarized : 
(i) The radiation from the skin and clothing is approximately 
that of a " black body " or perfect radiator. 

(2) Skin temperatures computed from melikeron radiation mea- 
surements are about 1° C. higher than skin temperatures measured 
directly with the thermoelement. This is not true on clothing or 
calorimeters. Apparently the melikeron sees deeper into the pores of 
the skin. 

(3) A cloth-covered, vertical, cylindrical calorimeter at body tem- 
perature loses in still air 60% by radiation, 40% by convection. A 
similar horizontal calorimeter loses 54% by radiation, 46% by con- 
vection. The human body convection loss is probably similar to this, 
that is, the convection loss is roughly one third less than the radia- 
tion loss, in still air and normal room temperatures. 

(4) Increasing air motion rapidly decreases the percentage radia- 
tion loss and increases the convectional. With the vertical calorimeter : 

Air motion % radiation loss 

60 

7S ft. per mill. 41 

130 ft. per mill. 35 

190 ft. per min. 25 

(5) Total body radiation similarly decreases with air motion: 

Air motion Radiation loss (mean for lo subjects) 

o to 50 ft. per mill. 30.7 large cal. per sq. m. per hour 

50 to 100 29.3 

100 to 150 25.7 

180 to 250 23.2 

(6) Increase in room teinperature (which also means increase in 
wall temperature) ])roduces a progressive lowering of radiation loss. 
The ratio 

Radiation loss 
Basal metabolism 
decreases with increase of room and wall temperature: 

Radiation loss 



Room temp. Basal metabolism 

^ ,, T J 21°. 3 .80 (mean of 10 subjects) 

1 24.1 .75 (mean of 10 subjects) 

(22.1 .84 (mean of 3 subjects) 

Table J J 24.5 .74 (mean of 4 subjects) 

1 25.6 .66 (mean of 3 subjects) 

(7) Keeping room and wall temperatures unchanged, the tem- 

l^erature of skin and clothing decreases with increasing air motion, 



NO. 6 BODY RADIATION ALDRICH 25 

the decrease being greatest on the side facing the wind and about 
one half as great on the side away from the wind. The clothing tem- 
perature drop on the side towards the wind is about one third greater 
than the corresponding skin temperature drop. Summary of lO 
subjects : 

Skin temp, drop— Clothing temp. drop- 

Air motion Away from Towards Away from Towards Perpendicular 

(ft. per min.) wind wind wind wind to wind 

o to 100 — ?4 — ?8 — ?6 — i?3 — ?5 

100 to 250 —.7 — 1.2 —.4 — 1.7 —.5 

(8) At normal indoor temperature, in still air and with the subject 
normally clothed and at rest, body heat losses are distributed as 
follows : 

Evaporation of water 24% 

Radiation 46% 

Convection 30% 

(9) Tests with the thermoelement show that the air temperature 
falls to room temperature very rapidly as the distance from the body 
increases. That is, there is a steep temperature gradient in the first 
centimeter or so from the body surface. With the thermoelement 
30 cm. away no effect of the presence of the body could be detected. 

(10) The Abbot-Benedict work (table A) indicates that the radia- 
tion loss from a nude subject is about twice as great for a room 
temperature of 15° as it is for a room temperature of 26? This evi- 
dence does not entirely support the " suit of clothes " theory referred 
to by Du Bois. In explanation of this theory, he says (p. 385, 1927 
ed. " Basal Metabolism") : "A constriction of the peripheral blood 
vessels (occurs) and the amount of heat carried to the surface is rela- 
tively small in proportion to the heat produced. . . . The patient 
really changes his integument into a suit of clothes and withdraws 
the zone where the blood is cooled from the skin to a level some 
distance below the surface." 

(11) Normal fluctuations in humidity indoors produce negligible 
effect upon the radiation loss. This is to be expected. Our bodies, 
about 300° Absolute, radiate almost wholly between the wavelengths 
4ja and S^p- with a maximum at lO/t. Water vapor absorption is so 
strong for much of this range and so nearly negligible near the maxi- 
mum, lO/x. that its possible effect is nearly fully produced even by the 
humidity of an ordinary room. Thus the effect of changes of quan- 
tity of water vapor in the ordinary room is small. Were the air of the 
room exceedingly dry, changes might be noticeable. 



26 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

Interesting and important questions concerning the comfort and 
welfare of children in classrooms are inadequately answered today. 
It is hoped that this report may in some degree help towards a better 
understanding of these problems. 

NOTES ON TABLES 

Temperatures are given in centigrade degrees. 

Air velocities are in feet per minute. 

Surface areas are determined from Du Bois' height-weight chart 
(Archives of Internal Medicine, Vol. 17, p. 865, 1916). 

Basal metabolism values are taken from Du Bois' " Basal Metab- 
olism in Health and Disease," edition 1927, p. 145. 

In table E, Wall A, B, C, D, E, refer to definite places on the 
canton-flannel curtains hung around the subject and forming the 
walls to which the subject is radiating. Places A, B, and D are on the 
sides, C on the ceiling and E on the floor. Position numbers followed 
by an asterisk are taken on the skin because of short sleeves or low 
socks. 

In table E also, skin temperatures in the three columns on the 
right are just as read from the thermoelement device. In the sum- 
mary on the left they have been corrected to the melikeron scale by 
the additfon of i°i as explained in the text. 



NO. 



BODY RADIATION ALDRICH 



27 



Table A. — Abbot- Betiedicl Observations 
Subject: Miss W, nude 













March 30, 


1921 








Observed 


Temp. 








Temp. 


Temp. 


Computed 








Water 


(thermo- 


from 




Time 


Pos. 


Jacket 


element) 


Radiation 


Remarks 


I 33 


19 


2I?I 


32-8 


34-1 


Pos. 14 cm. below 19. 


38 




20 


8 


33 


33 







45 


19a 


19 


8 


31-6 


31 


8 


Pos. 14 cm. below 19a. 


2 05 


55 


19 


3 


32.7 


40 


7 




10 




19 


I 


32.5 


36 


8 




18 




19 


I 


319 


39 


6 




29 


54 


19 


I 


330 


34 


2 


Pos. 10 cm. to left of 54. 


35 








32.7 


34 


2 




45 


55 


19 


5 


31.2 


36 


6 




58 


54 


19 


7 


32.2 


33 


3 


Pos. 10 cm. to left of 54. 


3 21 


32 


20 





27.8 


28 


4 


Standing facing window, holding iron 


27 


31 


19 


7 


27.2 


29 


3 


post to steady herself. 


38 


30 


19 


2 


27.7 


30 


6 


Pos. 2 cm. below 30. 




34 


18 


9 


30.3 


33 


7 


Pos. 6 cm. above 34. 


53 


45 


18 


7 


27.6 


30 


2 




4 01 


46 


18 


4 


27.7 


29 


9 




12 


14 


18 


7 


32.1 


34 


6 




20 


28 


18 


8 


26.6 


26 


4 






March 


31. 192 


Room Temp. 15 


.0 C. Outside Temp. 8.6 C. 






17.6 


30.9 


32.2 


Dr. B.'s hand. 






20 


8 


15-2 


29.9 


Floor. 






19 


4 




28.7 


45 toward wall and ceiling. 


10 23 


14 


17 


7 


32.0 


33-4 


Miss W., subject. 


34 


46 


17 


4 


26.7 


29.8 




39 


46 


17 


2 


26.0 


27.0 * 




45 


14 


17 


2 


29.6 


32.5 




53 


46 


17 


2 


25-1 


26.5 




56 


14 


17 


I 


295 


3r.7 




II 02 


46 


17 


2 


254 


26.8 




10 




17 


3 




21.5 


Toward ceiling. 


17 


14 


17 


3 


29.2 


314 




23 


46 


17 


3 


24.0 


25.2 




30 


32 


17 


4 


22.6 


239 




34 


30 


17 


4 


24-5 


26.1 




39 


3 


17 


4 


24.2 


26.1 




42 


28 


17 


6 


22.9 


245 




47 


34 


17 


6 


27.1 


29.1 




57 


53 


17 


8 


29.0 


31- 


8 





28 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 



Table A (continued) 
March 31, 1921 (continued) 



Time 


Pos. 


Temp. 
Water 
Jacket 


Observed 
Temp, 
(thermo- 
element) 


Temp. 
Computed 

from 
Radiation 


2 02 


54 


17-9 


26?5 


28?4 


10 
21 


55 
55 


179 
18.2 


25 -3 
25.6 


26. I 
26,8 


27 


54 


18.3 


25 -7 


28.0 


30 


53 


18.3 


28.9 


29.8 


2 00 




20.8 


35-4 


39-3 



Remarks 



20.8 



35-5 



37-7 



Subject lying down, melikeron held 
over her. 

Dr. M., subject, Rt. hand is made 
into a tube resting in left. 

Hands taken apart for skin temp., 
so that both palms were exposed. 

Palms not exposed, position held. 



April I, 1921. 

9 56 
10 01 



Subject: Miss W. 



10 
17 
24 
30 
36 
40 

53 

II 05 

12 

21 

2 55 



14 
46 

14 
46 

34 
2 
29 
32 
53 
54 
54 
53 



253 
24.6 

23 -9 
23.2 
22.9 
22.6 
22.4 
22.2 
21 .9 
21 .6 
21 .3 
20.9 
245 



Room Temp, held at 26.0 Outside 4.2 

Sitting. 
Standing. 
Sitting. 
Standing. 



36 1 



01 

03 
06 
12 
14 
41 
50 



23 -4 






33 


3 


22,9 


34 


5 


33 


3 


21.6 


35 


7 


34 


2 


20. 1 


35 





35 


7 


20.0 


35 


2 


35 


6 



Standing on stool. 



Dr. M, subject, Rt. hand made into 
a tube resting in left. Melikeron 
opposite hole made by hand. Ther- 
moelement with rubber back in- 
serted in hole made by hand. 

Opened hands and clapped them 
together again with thermoelement 
between. 

Hands in position of tube. 

Hands in position of tube. 

No rubber back. Mean of 13 values. 

No rubber back. Mean of 10 values. 
Hands made into tube. 



NO. 6 



BODY RADIATION ALDRICH 



29 



Table B. — Observations and Rcsnits of PrcUininary E.vpcriniotts on Ten 

Subjects 



Table Bi 



Date: Jan. 18, 1928. 

Subject: S. A. 

Sex: Male. 

Age: 7 yrs. 

Weight: 25.5 kg. 

Height: 124 cm. 

Surface Area: .95 sq. m. 

Clothing: Green, wool suit, cotton 

stockings. 
Air temperature outdoors, 10°. 
Relative humidity indoors, 40%. 
Room temperature, 21°. 5. 



Temperature Summary 



No. 
Values 



Temp, computed 

from Stefan 

formula 



Skin 3 33 . 7 

Clothing 5 28.5 

Hair i 29.9 

Shoes (est.) 25.6 

Wall (est.) 21.0 



Radiation Summary 

Calories per 
sq. cm. per min. 

Skin 1 131 

Clothing 0653 

Hair 0779 

Shoes 0396 



Place 



Water 
Jacket 
Temp. 



Temp. 
Temp, computed 
by from 

Thermo- Stefan 
Element Formula 



i8a 19 

26a 19 

100 19 

54 19 

II 19 

int. wall 19 

34 19 

30 19 

10 19 

int. wall 19 

loi 19 



5 


32. 


5 


27. 


6 


30. 


6 


23 


5 


27 


5 


21 


5 


25 


5 


23 


4 


27 


4 


21 


•4 


31 



340 
29.9 

33-2 
28.6 
28.9 
21 .2 
27.7 
27.2 

30.3 
20.9 
34 o 



Total Radiation 
36.9 large calories per sq. meter per 
hour. 



Basal Metabolism 
43 large calories per sq. meter per 
hour. 



30 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 



Table B2 



Date: Jan. 21, 1928. 

Subject: M. W. 

Sex: Female 

Age: II yrs. 

Weight: 28. i kg. 

Height: 140 cm. 

Surface Area: 1.07 sq. m. 

Clothing: Red, wool dress, cotton 

stockings. 
Air temperature outdoors, — 2°. 8. 
Relative humidity indoors 32%. 
Room temperature 22°. i. 



Temperature Summary 



Kind 



No. 
Values 



Skin .4 

Clothing 5 

Hair 2 

Shoes (est.) 

Wall (est.) 



Temp, computed 

from Stefan 

formula 

33-0 
26.7 
27.4 
24.0 
21 .6 



Radiation Summary 

Calories per 
sq. cm. per min. 

Skin 1012 

Clothing 0440 

Hair 0502 

Shoes 0207 



Place 



Water 
Jacket 
Temp. 



int. wall 20.7 

1 8a 20.7 

26a 20.7 

100 20.7 

54 20.7 

II 20.7 

int. wall 20.7 

34 20.7 

9 20.7 

1 8a 20.7 

26a 20.7 

int. wall 20. 7 

100 20.8 

54 20.8 



Temp. 
Temp, computed 
by from 

Thermo- Stefan 
Element Formula 



21 

2>2 
30 
31 
24 
25 
21 
26 
27 

31 

27 
21 
31 
24 



21 .7 

33-4 
28.4 

32.9 
26.0 
26.7 
21 .7 
26.3 
28.6 
32.2 
26.4 
21 .7 
33-6 
26. 1 



Total Radiation 
25.8 large calories per sq. meter per 



hour. 



Basal Metabolism 
44 large calories per sq. meter per 
hour. 



NO. 6 



BODY RADIATION ALDRICH 



31 



Table B3 



Date: Jan. 28, 1928. 

Subject: J. S. 

Sex: Male 

Age: 12 yrs. 

Weight: 46.2 kg. 

Height: 158 cm. 

Surface Area: 1.44 sq. m. 

Clothing: Cotton waist, corduroy 

trousers, high, red rubljer boots. 

(Snow storm outside) 
Air temperature outdoors — 4°-4. 
Relative humidity indoors 37%. 
Room temperature 19°. 7. 



Temperature Summary 



No. 

Values 



Skin 4 

Clothing 5 

Hair i 

Shoes 2 

Wall (est.) 



Temp, computed 

from Stefan 

formula 

32 . 2 
26.8 
29.4 
24.2 
19.2 



Radiation Summary 

Calories per 
sq. cm. per min. 

Skin. 1135 

Clothing 0642 

Hair 0878 

Shoes 0420 



Water 
Jacket 
Temp. 



l8a 19.2 

100 19.2 

26a 19.2 

ir 19. 1 

54 191 

33 192 

2 19. 1 

29 19. 1 

int. wall 19. 1 

10 19.2 

8 19.2 

int. wall 19.2 

i8a 19. 1 

roo 19. 1 



Temp. 
Temp, computed 
by from 

Thermo- Stefan 
Element Formula 



30 


8 


2>2. 


30 


4 


32. 


24 


I 


29. 


28 


6 


25- 


30 


I 


29. 


25 


2 


27. 


24 


7 


25 


25 


I 


26 


19 


4 


19 


22 


4 


23 


23 


7 


24 


19 


3 


19 


29 


5 


31 


29 


7 


32 



Total Radiation 
36.7 large calories per sq. meter per 
hour. 



Basal Metabolism 
44 large calories per sq. meter per 
hour. 



32 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 



Table B4 



Date: Jan. 31, 1928. 

Subject: S. \\'. 

Sex: Male. 

Age: 6 yrs. 

Weight: 18.2 kg. 

Height: hi cm. 

Surface Area: .76 sq. m. 

Clothing: Cotton waist, wool trousers, 

cotton stockings. 
Air temperature outdoors 0°. 
Relative humidity indoors 469c- 
Room temperature 21°. 8. 



Temperature Summary 



Kind 



No. 
Values 



Skin . _. 3 

Clothing 6 

Hair i 

Shoes I 

Wall (est.) 



Temp, computed 

from Stefan 

formula 

o 

27.7 
32.0 
25.6 
21.3 



Radiation Summary 

Calories per 
sq. cm. per min. 

Skin 1 134 

Clothing 0562 

Hair 0950 

Shoes 0372 



Water 
Jacket 
Temp. 



black velvet . 19 

i8a 19 

100 19 

26a 19 

54 19 

II 19 

.33 19 

int. wall 19 

2 19 

29 19 

10 20 

7 20 

1 8a 20 

int. wall 19 



Temp. 

by 
Thermo- 



Temp. 

computed 

from 

Stefan 



Element Formula 



21 .0 

32.3 
30.6 
30.6 
27.2 
28.2 
25.6 
21.3 
25.8 

25-7 
29.2 
23.0 
32.0 
21 .2 



20.5 
33-6 
33-6 
32.0 
28.7 
28.7 
27.2 
21 .6 
25.2 
26.8 
29.8 
25.6 
34-8 
21.3 



Total Radiation 

33.3 large calories per sq. meter per 
hour. 



Basal Metabolism 
44 large calories per sq. meter per 
hour. 



NO. 6 



BODY RADIATION ALDRICH 



33 



Table B5 



Date: Feb. 4, 1928. 

Subject: E. L. 

Sex: Female. 

Age: 8 yrs. 

Weight: 24 kg. 

Height: 127 cm. 

Surface Area: .93 sq. m. 

Clothing: Cotton dress and stockings. 

Air temperature outdoors 13°. 4. 

Relative humidity' indoors 46%. 

Room temperature 22°. 4. 



Kind 



Temperature Summary 

No. Temp, computed 



Values 



Skin 4 

Clothing 5 

Hair i 

Shoes I 

Wall (est.) 



from Stefan 

formula 

o 

34 7 
28.6 
28.7 
28.6 
21 .9 



Radiation Summary 

Calories per 
sq. cm. per min. 

Skin 1 1 52 

Clothing 0592 

Hair 0598 

Shoes 0592 



Water 
Jacket 
Temp. 



le 20.9 

100 20.9 

26a 20.9 

54 20.9 

II 20.9 

33 20.9 

2 20.9 

10 20.9 

8 20,9 

int. wall 20.9 

18 20.9 

loi 20.9 



Temp. 
Temp, computed 
by from 

Thermo- Stefan 
Element Formula 



32 


I 


35- 


31 


.1 


34- 


27 


9 


28 


28 


6 


30 


29 


2 


29 


25 





27 


25 





25 


29 


4 


31 


^1 


I 


28 


22 


4 


21 


32 


2 


35 


31 


5 


33 



Total Radiation 
35.2 large calories per sq. meter per 
hour. 



Basal Metabolism 
42 large calories per sq. meter per 
hour. 



34 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 



Table B6 



Date: Feb. 4, 1928. 

Subject: R. S. 

Sex: Male. 

Age: 10 yrs. 

Weight: 31.8 kg. 

Height: 138 cm. 

Surface Area: i.io sq. m. 

Clothing: Cotton waist, grey, wool 

trousers, stockings. 
Air temperature outdoors 8°. 3. 
Relative humidity indoors 46%. 
Room temperature 21 ".4. 



Temperature Summary 



Kind 



No. 

Values 



Temp, computed 

from Stefan 

formula 



Skin 3 

Clothing 6 

Hair i 

Shoes I 

Wall (est.) 



34 
2-] 
28 

25 
20 



Radiation Summary 

Calories per 
sq. cm. per min. 

Skin 1203 

Clothing 0566 

Hair 0652 

Shoes 0420 



Total Radiation 

33 . r large calories 

per sq. meter per hour 



Place 



Water 
Jacket 
Temp. 



18 20.6 

100 20.5 

26a 20.4 

54 20.6 

II 20.8 

.33 20.9 

int. wall 20.9 

29 20.9 

2 20.9 

10 20.9 

8 20.9 

loi 20.9 

int. wall 20.8 



Temp. 
Temp, computed 
by from 

Thermo- Stefan 
Element Formula 



33 o 
30.8 
27.6 

259 
28.0 

27-5 
21 .2 

25-3 
25-7 
28.0 

23-4 
30.5 
21 .6 



35 
35 
28 
28 



I 
I 

4 
6 

27-7 
27.2 
21.3 
26.5 
25-8 
295 
25-7 
33-3 
21.5 



Basal Metabolism 
42 large calories per sq. meter per 



hour. 



NO. 6 



BODY RADIATION — ALDRICH 



35 



Table B7 



Date: Feb. 11, 1928. 

Subject: P. L. 

Sex: Female. 

Age: 8 yrs. 

Weight: 25.9 kg. 

Height: 129 cm. 

Surface Area: .96 sq. m. 

Clothing: Cotton dress, short sleeves, 

cotton stockings. 
Air temperature outdoors 6°. 
Relative humidity indoors 46%. 
Room temperature 2i°.9. 



Temperature Summary 



Kind 



No. 
Values 



Skin 2 

Clothing 6 

Hair i 

Shoes I 

Wall (est.) 



Temp, computed 

from Stefan 

formula 

34-8 
26.8 
27.7 

251 
21 .4 



Radiation Summary 

Calories per 
sq. cm. per min. 

Skin 1204 

Clothing 0465 

Hair 0555 

Shoes 0315 



Place 



Water 
Jacket 
Temp. 



lor 20.9 

18 20.9 

26a 20.9 

54 20.9 

22 20.9 

34 20.9 

2 20.9 

29 20.9 

10 20.9 

7 20.9 



Temp. 
Temp, computed 
by from 

Thermo- Stefan 
Element Formula 



29-7(?) 35 

32.8 

27.9 

25.6 

27.4 

253 
24.0 

251 
29. 1 

251 



Total Radiation 
28.1 large calories per sq. meter per 
hour. 



Basal Metabolism 
42 large calories per sq. meter per 



hour. 



36 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 



Table B8 



Date: Dec. 13, 1927. 
Subject: M. M. 
Sex: Female. 
Age: 2"] yrs. 
Weight: 61.3 kg. 
Height: 165 cm. 
Surface Area: 1.67 sq. m. 
Clothing: Dark silk dress, silk stock 
ings. 

Air temperature outdoors — — 
Relative humidity indoors 59%. 
Room temperature 22°. 6. 



Temperature Summary 



No. 
Values 



Skin 2 

Clothing 4 

Hair i 

Shoes (est.) 

Wall (est.) 



Temp, computed 

from Stefan 

formula 

o 

31 -4 
29.8 
26.6 
27.0 
22. 1 



Radiation Summary 

Calories per 
sq. cm. per min. 

Skin 0830 

Clothing 0676 

Hair 0390 

Shoes 0426 



Place 



Water 
Jacket 
Temp. 



18 19 

26a 19 

100 19 

54 19 

II 19 

34 19 

30 19 



Temp. 
Temp, computed 
by from 

Thermo- Stefan 
Element Formula 



31-4 
26.6 

31.6 

31 9 
28.2 
27.4 



Total Radiation 
35.9 large calories per sq. meter per 
hour. 



Basal Metabolism 

37 large calories per sq. meter per 
hour. 



NO. 6 



BODY RADIATION ALDRICH 



Z7 



Table B9 



Date: Dec. 9, 1927. 

Subject: K. B. 

Sex: Male. 

Age: 21 yrs. 

Weight: 61.3 kg. 

Height: 173 cm. 

Surface Area: 1.73 sq. m. 

Clothing: Woolen shirt and trousers, 

thick leather boots. 
Air temperature outdoors, — ^2°. 8. 
Relative humidity indoors 38%. 
Room temperature 18.4. 



Temperature Summary 



Kind 



No. 
Values 



Skin 5 

Clothing 4 

Hair (est.) 

Shoes I 

Wall (est.) 



Temp, computed 

from Stefan 

formula 

30.5 
26.0 
27.0 
23.6 
17.9 



Radiation Summary 

Calories per 
sq. cm. per min. 

Skin 1077 

Clothing 0681 

Hair 0766 

Shoes 0473 



Place 



Water 
Jacket 
Temp. 



loi 20.4 

18 20.3 

19 20.4 

II 20.4 

3 20.4 

10 20.5 

loi 20.5 

18 20.5 

10 22.6 

18 22.6 



Temp. 

by 

Thermo- 

Element 



29 


5 


31 


21 


I 


29 


25 


2 


27 


25 


9 


25 


24 


6 


25 


23 


I 


23 


30 


6 


2>i 


25 


9 


25 


24 


3 


26 


32 


5 


33 



Temp. 

computed 

from 

Stefan 
Formula 



Total Radiation 
38.2 large calories per sq. meter per 
hour. 



Basal Metabolism 
39.7 large calories per sq. meter per 
hour. 



38 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 



Date: Dec. 21, 1927. 
Subject: L. A. 
Sex: Male. 
Age: 45 yrs. 
Weight: 74.6 kg. 
Height: 179 cm. 
Surface Area: 1.93 sq. m. 
Clothing: Dark wool suit. 
Air temperature outdoors . . 
Relative humidity indoors 37%. 
Room temperature 2i°.3. 



Table Bio 



Place 



Temperature Summary 



Kind 

Skin 

Clothing. . . 

Hair 

Shoes 

Wall (est.) 



No. 
^alues 


Temp, computed 

from Stefan 

formula 


I 


31.6 


I 


27.2 


(esV) 


29.4 
24-5 



20.8 



Radiation Summary 

Calories per 
sq. cm. per min. 

Skin 0950 

Clothing 0552 

Hair . .0752 

Shoes 0317 



Water 
Jacket 
Temp. 



i»a 19-3 

26a 19.3 

iia 193 



Temp. 
Temp, computed 
by from 

Thermo- Stefan 
Element Formula 



33-9 
317 
25.0 



31.6 
29.4 
27.2 



Total Radiation 
31.4 large calories per sq. meter per 
hour. 



Basal Metabolism 
39.7 large calories per sq. meter per 
hour. 



NO. 6 



BODY RADIATION ALDRICH 



39 



Table C. — -Preliminary Tests of Cylindrical Copper Calorimeters, Cloth-covered 



















Vertical 






Horizontal 




Amount of copper. 














2.91 kg. 




2 . 60 kg. 


Amount 


of brass. . 














1 .50 




•50 
27.20 


Amount of water.. . 














26.70 




Total water equiva 


ent. . . . 












27.05 kg. 




27.48 kg. 


Area of calorimeter 












..5103. sq. 


cm. 


5103. sq. cm. 














Ur 




Mean Melik. 


Loss of Heat 












\'elocitv 




Temp. Water 


in calories 


Date 


Calor- 


Room 


Outside 


(f 


eet 




Cal. Jacket 


per hour 


1928 


imeter 


Temp. 


Temp. 


per 


min. 


) 


Water Temp. 


(large cal.) 


Feb. 29 


Vert. 


2I?9 


II 


7 









3o?4 20 


8 


2i?36 


Mar. I 


Vert. 


23 -7 


8 


9 









32.1 22 


2 


19-57 


Mar. 3 


Vert. 


22.9 


6 


7 


about 
300 




32.0 20 


4 


38-42 


Mar. 15 


Horiz. 


245 


14 


4 









32.0 24 


3 


19 63 


Mar. 1 6 


Horiz. 


22.0 


3 


3 









32.4 22 


7 


27-75 


Mar. 26 


Horiz. 


255 


17 


2 









32.5 22 


6 


12.86 (no cloth 


Apr. 21 


Vert. 


24.1 


8 


3 









37-5 22 


7 


cover) 


Apr. 25 


Vert. 


22.8 


13 


9 









317 19 







Apr. 25 


Vert. 


23 -5 


15 












31.7 22 


6 




















Mean 














Mean 






Temp. 




Loss by 










Temp. 






Cal. 




Radia- 




Esti- 






Cal. 






Surface 


tion (in 




mated 






Surface 






(computed 


large % 




Wall 


No. 




(Thermo- 




No 


from 




cal. per Rad- 


Date 


Temp. 


\'alues 


element) 


Values Melik. 




hour) iated 


1928 






















Feb. 29 


21.4 


II 




27 







5 


28.2 




17.07 80. 


Mar. I 


23.2 


12 




29 







4 


29.1 




15 


83 81 




Mar. 3 


22.4 


17 




25 


6 




6 


29.2 




18 


25 47 




Mar. 15 


24.1 


18 




29 







6 


293 




14 


00 71 




Mar. 16 


21-5 


l8 




28 


4 




6 


295 




21 


45 77 




Mar. 26 


25-1 


18 




30 


7 




4 


26.7 




4 


41 34 




Apr. 21 
Apr. 25 
Apr. 25 




28 




32 
28 


2 




4 
4 
4 


:S2.7 
30.2 
29.4 












27 

27 




I 












...» 




28 


6 













40 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 



Table D 


— Tests 


0/ Verlica 


I Calorimeter, Clo 


th-cove 


''f^/, Surroiina 


ed by 


a 


oth Walls 










Air 
\^el. 


Mean 


Me 


ik. 


Loss of 




No. of 








Out- 


(feet 


Temp. 


Water 


Heat in 


Mean 


places 


Date 




Room 


side 


per 


Cal. 


Jacket 


large cal. 


Wall 


wall temp. 


1928 




Temp. 


Temp. 


min.) 


Water 


Temp. 


per hour 


Temp. 


measured 


Apr. 


27 


2I?6 


9-4 





34-2 


21 


•3 


31.80 


22?0 


19 


Apr. 


27 


21.4 


9-4 





32 





21 


•4 


24 


70 


22.2 


16 


Apr. 


28 


22.4 


8.9 





30.9 


22 


•5 


21 


95 


22.9 


18 


May 


I 


22,9 


20.6 





34 


5 


23 


. I 


25 


40 


24-7 


13 


May 


I 


23-9 


20.6 


130 


33 


9 


23 


.2 


33 


50 


24.6 


II 


May 


3 


24.7 


27.2 





31 


2 


24 


.2 


15 


70 


26.0 


10 


May 


3 


25.0 


27.2 


75 


30.9 


24 


. 2 


16 


75 


25-9 


9 


May 


5 


28.5 


33-9 


75 


39 


5 


28 


•5 


34 


05 


29-9 


12 


May 


5 


28.8 


33-9 


130 


38 


8 


28 


•5 


35 


15 


29.7 


12 


May 


7 


24.4 


20.0 


190 


36 


4 


25 


.6 


47 


60 


25.0 


12 


May 


7 


24.4 


20,0 


190 


35 


6 


25 


•4 


43 


80 


25.0 


12 










Mean 
























Temp. 




















Mean 




Cal. 






Loss 


by Radiation 










Temp. 




Surface 








in 


arge cal. per 










Cal. 
Surface 
(Thermo- 


No. of 
places 
meas- 


(com- 
puted 
from 




No. of 
placet 
meas- 






hour 


% Radiated 


Datf 






^ 




Thermo- 


' 


Thermo- 


1928 




element) 


ured 


Melik.) 





ured 




Me 


ik. element 


Melik. 


element 


Apr. 


27 


29 5 


26 


29. I 




4 




18 


95 20.06 


59-5 


63.2 


Apr. 


27 


28 


I 


24 


28.1 




4 




15 


70 15.70 


63 


5 


63-5 


Apr. 


28 


27 


9 


22 


28.2 




4 




14 


13 13-40 


64 


4 


61.2 


May 


I 


30 


5 


16 


30.6 




4 




16 


07 15.64 


63 


3 


61.6 


May 


I 


29 


2 


22 


30.6 




4 




16 


43 12.54 


49 





37-4 


May 


3 


28 


9 


8 


29-3 




4 




8 


88 7-93 


56 


5 


50.5 


May 


3 


28 


5 


9 


28.2 




4 




6 


17 6.94 


36 


8 


41-5 


May 


5 


34 


7 


16 


34-7 




4 




13 


84 13-84 


40 


7 


40.7 


May 


5 


33 


7 


16 


33-8 




4 




II 


55 11-30 


32 


8 


32.2 


May 


7 


29 


I 


16 


314 




3 




17 


70 I I . 04 


37 


2 


23.2 


May 


7 


29 


2 


16 


31-7 




3 




18 


50 


II .42 


42 


2 


26.1 



NO. 6 



BODY RADIATION ALDRICH 



41 



Table E. — Observations and Results of Experiments on Ten Subjects in Still 

and in Moving Air 



Table Ei 



Date: May 30, 1928. 

Subject: S. A. 

Sex: Male. 

Age: 7 yrs. 5 mos. 

Weight: 24 kg. 

Height: 127 cm. 

Surface Area: .93 sq. m. 

Clothing: Woolen sweater, cotton 

trousers, socks. 
Air temperature outdoors, 2i°.i. 
Relative humidity indoors, 56%. 



Temperature Summary 



Kind 



Skin 

Clothing. 

Hair 

Shoes .... 
Wall 



No. 
Values 

7 
15 

I 

2 
10 



Temp, at air vel. 



Room 2 





o 

34-1 
28.4 
33-8 
26.2 
21 . 1 
19.8 



130 



32 


3 


31 


I 


27 


3 


26 


3 


34 


2 


32 


4 


27 


4 


25 


2 


22 





21 


3 


21 


3 


20 


9 



Radiation Summary 

Calories per sq. cm. 
per min. at air vel. 
130 180 

Skin 1157 .0915 .0865 

Clothing 0641 .0457 .0433 

Hair 1131 .1094 .0990 

Shoes 0444 . 0468 . 0337 



Total Radiation 

Air vel. Calories per hour 

per sq. meter 

o 38.6 

130 29.4 

180 27.2 



Place 



Temperatu 




room 19-7 

wall A 19.0 



26. 
100. 

lOI. 

19a. 
19- 



20.8 
21 .7 
20.8 
19.4 
34-6 
30.8 

32.3 
27.8 
28.3 

54 28.0 

295 
28.8 

295 
27.6 

33-1 
32.5 
33-4 
34-1 
26.9 
26.9 
26.9 
25.6 
33.8 
29. 1 



2. 

3- 

23- 

22. 

18. 

i8a. 

17- 
17a. 

9- 
10. 

8. 

7- 
26a. 

35- 



36 28.6 

29 30.4 

30 30.5 

27 27.4 

28 27.3 

wall A 22 . 1 



B 22 . 1 

C 23.6 

D 21.7 

E 19.8 

room 19.9 



res at Air 
130 

o 

21 . I 
21 .4 
21.3 
2^.4 
21 .6 
20.6 
350 
30.2 
29.7 
26.7 
24.8 
25-1 

28.5 
27.7 
28.5 

27-3 
30.2 
30.8 
31-7 
30.5 
27.9 
26.3 
27.4 

27-5 
34-2 
27-3 
27-3 
30.0 
27.2 

27-3 

27.8 
22.5 
22.9 

22.8 
21 . 1 
21.5 



Velocity 

180 

o 

20.9 

21 .0 
21 .2 
21 .9 
21. I 
19.4 

33-6 

30.1 

295 
24.1 
23.6 
23.6 

235 
27.0 
27.0 
27.9 
30.0 
29.9 

30 -5 
29.7 
27.7 
24.8 
25.0 
255 
32.4 
26.7 

27-5 
293 
27-5 
26.8 
26.4 
21.3 
20.4 
24.4 
21 .6 
20.9 
21 .0 



42 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 



Date: July 12, 1928. 

Subject: S. W. 

Sex: Male. 

Age: 6 yrs. 6 mos. 

Weight: 18 kg. 

Height: i 16 cm. 

Surface Area: .78 sq. m. 

Clothing: Tan cotton suit, socks. 

Air temperature outdoors, 27°. o. 

Relative humidity indoors, 68%. 



Table E2 

Place 



Temperature Summary 



Kind 



Skin 

Clothing . 

Hair 

Shoes . . . . 

Wall 

Room . . . 



No. 
Values 

I I 
II 

I 

2 
10 

2 



Temp, at air vel. 
15 50 



34-4 
31,8 

35 I 
28.4 
26.0 
25 I 



33-7 
30.2 

32.7 
28.1 

239 
23.1 



Radiation Summary 

Calories per sq. cm. 
per min. at air vel. 
15 50 

Skin 0766 .0838 .0878 

Hair 0835 .0818 .0785 

Clothing 0521 .0619 .0552 

Shoes 0215 .0327 .0362 



Total Radiation 

Air Vel. Calories per hour 

per sq. meter 

o 29.3 

15 34-4 

50 32 . I 



Temperatures at Air 
15 



room 24 . 9 

wall A 25 . 7 

B 25.7 

C 26.0 



26. 
100. 

lOI . 

19a. 
19- 

54- 



3-- 
23 •• 
22. . 
18.. 

i8a.. 
17.. 

17a. . 

9* 
10'. 



7 

26a 

35 

36 

29 

30 

27* 

28* 

wall A 26 . 6 

H 26.6 

C 26.7 

D 26.2 

E 25.8 

room 25 . 3 



25,6 

25 I 
35-6 
32.0 

33 I 
33-2 
32.6 
30.2 

295 
32.0 

32 . 5 
32.6 
34-8 
33-9 
35 I 
34-3 
32.4 
32 -4 
28.7 
28.2 

35 I 
33 I 
32.0 
29.9 

31 9 
31.6 

31-3 



23 


2 


23- 


23 


9 


23- 


23 


8 


23- 


24 


3 


23- 


24 





23- 


23 


9 


23- 


35 


5 


35- 


31 


7 


31- 


33 


3 


32- 


33 


2 


32. 


32 


9 


31- 


31 


7 


32- 


30 


7 


28. 


30 





28. 


31 


8 


31- 


32 


I 


31 


34 


4 


33- 


33 


8 


33- 


33 


3 


34 


33 


3 


33 


30 


3 


31 


31 


5 


31 


29 





28 


27 


4 


27. 


33 


6 


32. 


32 





29. 


32 


2 


30 


29 





27 


30 





27 


30 


9 


31 


32 


I 


30 


25 


4 


24 


25 


I 


24 


25 


/ 


24 


24 


3 


23 


24 


3 


24 


23 


3 


23 



Velocity 
50 



NO. 6 



BODY RADIATION ALDRICH 



43 



Table E3 



Date: July 12, 1928. 

Subject: M. W. 

Sex: Female. 

Age: II yrs. 5 mos. 

Weight: 27.5 kg. 

Height: 143 cm. 

Surface Area: 1.07 sq. m. 

Clothing: Light cotton dress, socks. 

Air temperature outdoors, 27.0. 

Relative humidity indoors, 68%. 



Temperature Summary 



Kind 



No. 
Values 



Temp, at air vel. 
15 50 



Skin 7 

Clothing. ... 15 

Hair i 

Shoes 2 

Wall 10 

Room 2 



35 
31 
33 
31 
25 
24 



.0 


35 I 


34- 


.6 


311 


30. 


.8 


33-4 


31- 


•3 


29.6 


27. 


■7 


245 


24. 


•5 


23.2 


23- 



Radiation Summary 

Calories per sq. cm. 

per min. at air vel. 

15 50 

Skin .0851 .0965 .0882 

Clothing 0525 .0587 .0528 

Hair 0730 .0803 .0677 

Shoes 0498 . 0447 . 0296 



Total Radiation 

Air Vel. Calories per hour 

per sq. meter 

o 310 

15 34-2 

50 30 . 2 



Temperatures at Air Velocity 
15 50 



room 25 

wall A 25 



... 25 
... 26 
... 25 
... 25 
34 
33 
... 32 
... 32 

■ ■ 33 
■ 33 

31 
31 
31 
... 31 
33 
34 

■ ■ 34 

■ ■ 34 
31 

... 31 

31 
... 31 

■ ■ 33 
• • ■ 33 
... 30 

.... 29 

.... 29 

. . ■ . 30 

.... 31 

wall A 26 



26.. 
100. . 

lOI.. 

19a. 
19. 

54- 
2. 

3- 

23- 

22. 

18. 

i8a. 

17- 
17a. 

9- 
10. 



7- 
26a. 

35- 
36. 
29. 
30. 

27. 
28. 



room 24 



23 
24 
23 
24 
24 
24 
34 
33 
32 
33 
32 
33 
28 
28 
31 
31 
33 
33 
35 
35 
30 
32 
30 
29 
33 
32 
33 
29 
29 
29 
30 
25 
25 
25 
24 

24 



3 


23.2 


3 


24.0 


9 


23 -7 


8 


24.6 





23.6 





239 


6 


34-5 


5 


32.8 


5 


32.0 





330 


6 


319 


4 


33-4 


4 


28.2 


9 


28.1 


4 


31.0 


8 


31 r 


6 


32.7 


8 


32.6 





32.5 


2 


32.9 


7 


315 


2 


31.0 





27.6 


2 


27.6 


4 


3i« 


7 


30.5 





315 


I 


27.6 


2 


259 


5 


29.2 


.6 


29.7 


.2 


24.6 


.0 


24.2 


•3 


251 


•3 


24.1 


•3 


239 


.0 


23.2 



44 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOL. 



Table E4 



Date: July 14, 1928. 

Subject: T. L. 

Sex: Male. 

Age: 14 yrs. 3 mos. 

Weight: 43.5 kg. 

Height: 152 cm. 

Surface Area: 1.36 sq. m. 

Clothing: Cotton waist, black woolen 

trousers, canvas shoes, high socks. 
Air temperature outdoors, 27°. 8. 
Relative humidity indoors, 68%. 



Temperature Summary 



Kind 



Skin 

Clothing. . . 

Hair 

Shoes 

Wall 



No. 
Values 

7 
15 

I 

2 
10 



Temp, at air vel. 
84 136 



Room 2 



34-3 


33- 


30.3 


29. 


31 -I 


31- 


28.4 


29. 


23.8 


23- 


22.5 


22. 



32. 1 
29.2 
29.6 

27.9 
23.2 

22.8 



Radiation Summary 

Calories per sq. cm. 
per min. at air vel. 
84 136 

Skin 0943 . 0892 . 0790 

Clothing 0569 .0509 .0527 

Hair 0647 . 0708 . 0558 

Shoes 0405 .0491 .0414 



Total Radiation 



Air vel. 

O 

84 

136 



Calories per hour 
per sq. meter 

32.5 
30.2 
29.7 



Place 



Temperat 




ures at Air 
84 



room 22.4 

wall A 23.8 

B 23.2 

C 23.8 

D 23.3 

E 23.4 

26 33.9 

100 31 .2 

loi 31-7 

19a 31.2 

19 311 

54 29.2 

2 28.7 

3 ^1-1 

23 3I-I 

22 31 .6 

18 33.2 

i8a 33.3 

17 34-7 

17a 34-6 

9 30.8 

10 317 

8 28,2 

7 28.6 

26a 31. 1 

35 30.3 

36 31-2 

29 28.7 

30 29.9 

^1 30.3 

28 30.5 

wall A 24.6 

B 23 . 9 

C 24.6 

D 23 . 9 

E 24.0 

room 22 . 6 



23 
22 

22 
23 
32 
30 
31 
30 
30 
30 
28 
26 
30 
30 

33 
32 
33 
32 
30 
31 
29 
29 

31 
28 
29 

2-] 
27 
29 
30 
23 
2?> 
24 

23 
24 

22 



Velocity 
136 

22.8 
23.1 
22.8 

23-3 

22.8 
22.9 
330 
29.8 
30.0 
31.0 

30.5 
29.4 
28.7 
28.6 
29.6 
311 
311 
30.8 
32.0 
30.1 
30.5 
30.7 
28.2 
27.7 
29.6 
28.1 
28.1 
26.2 

27-3 
29.2 

28.7 

23-7 
22.3 

23.1 
24.6 
22.8 



NO. 6 



BODY RADIATION ALDRICH 



45 



Table E5 



Date: J 


jly 18, 1928 1 


Subject 


P. L. 




Sex: Female 




Age: 8 yrs. 5 mos 




Weight: 


26 kg. 




Height: 


131 cm. 




Surface Area: . 


98 sq. m. 


Clothing: Light, 


cotton dress, high 


socks. 






Air temperature outdoors, 28° to 33°. | 


Relative 


humidit\ 


indoors, 61%. 


Temperature Summary | 


Kind 


No. 


Temp, at air veL 




Values 97 235 1 


Skin .... 


.... 7 


34.2 34.4 33.6 


Clothing 


... 15 


30.8 30.3 29.9 


Hair.... 


. . . . I 


32.5 32.2 31.4 


Shoes . . . 


. . . . 2 


29.4 29.2 28.1 


Wall .... 


. . . . ID 


25.2 25.1 25.5 


Room . . 


2 


24.1 24.3 24.6 




Radiation Summary 






Calories per sq. cm. 






per min. at air vel. 






97 235 


Skin .... 




.0818 .0850 .0734 


Clothing 




.0502 .0463 .0359 


Hair.... 




.0658 .0643 .0536 


Shoes . . . 




•0374 -0368 .0231 




Total 


Radiation 


Air veL 




Calories per hour 
per sq. meter 







29.0 


97 




27.4 


235 




21.4 



Place 



Temperatures at Air 
97 



room 24.2 

wall A 25 . o 

B 24.9 

C 25.9 

D 24.7 

E 24.4 

26 34.5 

100 31.5 

loi 31 .6 

19a 32.0 

19 315 

54 30.8 

2 28.9 

3 29.8 

23 31-7 

22 32.0 

18 330 

i8a 32.6 

17 34-9 

17a 33-5 

9 29.8 

10 31. 1 

8 29.4 

7 29.4 

26a 32.5 

35 319 

36 32-7 

29 30.0 

30 29.4 

^1 30.0 

28 30.1 

wall A 26.0 

B 25.3 

C 26.3 

D 25.1 

E 24.6 

room 24 . o 



24.1 
24.6 
24- 5 
25-5 
24-5 
24.4 
34-6 
31-7 
31-3 
29.9 

314 
30.6 
30.2 
31-4 
311 
309 
33-4 
33-8 
33-8 
34-6 
30- 5 
30.5 
29.2 
29.2 
32.2 
30.0 

304 
29.6 
27.9 
29.6 
29.8 
25.6 

253 
26.4 
25.0 
24.9 
245 



Velocity 

235 

o 

245 
24.7 
250 

26.2 

255 

25-3 
34-4 
311 
311 
295 
31.2 
31.2 

30.5 
29.0 
31.0 
30.1 
32.1 
32.9 
33-3 
32.6 
30.0 
31.2 
28.2 
28.0 

314 
29.8 
31-8 
26.6 
26.9 
29.2 
29.8 
25-4 
25 -5 
26.6 

25-3 
25-4 
24.8 



46 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 



Table E6 



Date: July i8, 1928. 

Subject: M. A. 

Sex: Female. 

Age: 55 yrs. 

Weight: 64.5 kg. 

Height: 167 cm. 

Surface Area: 1.73 sq. m. 

Clothing: Light, cotton dress, black 

stockings. 
Air temperature outdoors, 28° to 33°. 
Relative humidity indoors, 61%. 



Temperature Summary 



Kind 



No. 
Values 



Temp, at air vel. 
97 235 



Skin 

Clothing . 

Hair 

Shoes . . . . 

Wall 

Room . . 



15 
I 



35 I 


34 6 


34- 


31 I 


30.7 


30. 


28.4 


26.7 


27- 


29.2 


293 


28. 


25-5 


25-3 


25- 


24.0 


24.2 


24. 



Radiation Summary 



Skin 0883 

Clothing 0504 

Hair 0262 

Shoes 0332 



Calories per sq. cm. 
per min. at air vel. 
97 235 

.0853 .0812 

. 0490 . 0464 

.0126 0194 

.0356 .0268 



ToT.\L Radiation 

Air vel. Calories per hour 

per sq. meter 

o 28.0 

97 26.8 

235 25.2 



Place 



Temperatures at Air Velocity 
97 235 



room 24 

wall A 24 

B 25 

C 26 

D 24 

E 24 

26 33 

100 32 

loi 32 

19a 30 

19 30 

54 31 

2 29 

3 30 

23 31 

22 30 

18 34 

i8a 33 

17 35 

17a 35 

9 31 

10 31 

8 29 

7 29 

26a 28 

35 32 

36 31 

29 31 

30 31 

^1 31 

28 31 

wall A 28 

B 26 

C 26 

D 25 

E 24 

room 24 



24 

24 
25 
26 

24 
24 
33 
^■^ 
31 
29 
30 
30 
30 
30 
31 
30 
-i2, 
33 
35 
34 
31 
31 
29 
29 
26 
30 
31 
30 
30 
31 
31 
25 
25 
26 

25 
24 
24 



245 
24.7 
25.0 
26.5 
24.9 

243 
33-2 
32.0 
316 
30.1 

30.7 
31.6 

311 
32.0 
30.6 
30.1 
33 I 
33 I 
34- 1 
34-5 
31-7 
30.7 
275 
29.2 

27-5 
29.2 
29.6 
29.9 
29-3 
307 
30 -4 
25.2 

259 
27.0 
25.2 
24.6 

24.7 



NO. 6 



BODY RADIATION ALDRICH 



47 



Table Ey 



Date: July 19. 1928. 

Subject: M. B. 

Sex: Female. 

Age: 4 yrs. 8 mos. 

Weight: 15 kg. 

Height: 100 cm. 

Surface Area: .65 sq. m. 

Clothing: Light, cotton dress, no 

sleeves, high socks. 
Air temperature outdoors, 29° to 33". 
Relative humidity indoors, 58%. 



Place 



Temperatures at Air 
140 



Temperature Summary 



Kind 



No. 
Values 



Temp, at air vel. 



Skin 9 

Clothing.... 13 

Hair i 

Shoes 2 

Wall 10 

Room 2 





o 

33-7 
31.2 
32.0 
29.0 
25.6 
24.6 



140 



235 



34-2 


34- 


30.7 


30. 


29.7 


29. 


29.2 


2«. 


25-8 


25- 


24.9 


25- 



Radiation Summary 

Calories per sq. cm. 
per min. at air vel. 
140 235 

Skin 0696 .0764 -0772 

Clothing 0505 0442 0398 

Hair 0578 .0346 .0272 

Shoes 0302 .0302 .0265 



Air vel. 

O 
140 
235 



ToT.AL Radiation 

Calories per hour 
per sq. meter 

28.1 
25.2 
23.1 



room 24 . 5 

wall A 25.3 

B. . . 

C. . . 
D... 
E. . . 

26 

100 

lOI 

19a 

19 

54 



.. 25.1 
26. 1 

.. 25.1 

.. 24.8 

.. 32.2 

.. 320 

■ ■ 32.4 
.. 32.0 
.. 31-2 
•■ 30.9 
.. 31.6 
.. 30.8 
.. 320 

• ■ 320 

■ • 324 

■ • 324 

• • 341 
•• 33-9 
.. 310 
.. 32 I 
.. 28.4 
.. 29.7 

■ • 320 
... 30.7 
... 31-8 
... 31-2 
... 302 
... 31 I 
... 31-2 

wall A 26.1 



3- 

23* 

22* 

18. 

i8a. 

17- 
17a. 

9- 
10. 



7- 
26a. 

35- 
36. 
29. 
30. 

27. 
28. 



B 26.1 

C 26.8 

D 25.6 

E 25.2 

room 24 . 7 



24.4 
25.2 
25.2 
26.3 
25.2 
25.0 

33-7 
32.6 

30.7 
30.1 

32.5 
30.1 
29.9 
32.1 
32.0 
32.8 

33-1 
33-9 
34-7 
31.3 
319 
28.9 
29.6 

29.7 
29.8 
32.1 
29.2 
29.8 
3I-I 
30.5 
26.2 
26.3 
27.0 
25.8 
25.6 
254 



Velocity 

235 

o 

24.9 

253 
25.8 
26.6 
254 
25-1 

33-8 
32.6 

32 -9 
30.6 
30.7 
32.3 
31-7 
31-I 
32.5 
32.6 
33-6 
33-6 
34-4 
33-7 
30.3 
3I-I 
29.8 
28.0 
29.0 
28.8 

31-5 
28.3 
28.6 
29.8 

30.3 
26. 1 
26.3 
27.0 
259 
25-3 
25.6 



48 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 



Table E8 



Date: July 19, 1928. 

Subject: G. B. 

Sex: Female. 

Age: 30 yrs. 

Weight: 59 kg. 

Height: 157 cm. 

Surface Area: 1.59 sq. m. 

Clothing: Light, cotton dress, short 

sleeves, tan stockings. 
Air temperature outdoors, 29° to 33°. 
Relative humidity indoors, 58%. 



Temperature Summary 



Kind 



No. 
Values 



Temp, at air vel. 
140 235 



Skin 7 

Clothing. ... 15 

Hair i 

Shoes 2 

Wall 10 

Room 2 



34-9 
31.6 

31-9 
30.6 
26.0 

24.8 



34-1 


33- 


30.8 


30. 


3I-I 


30. 


29.8 


30. 


25-9 


26. 


25 I 


25- 



Radiation Summary 

Calories per sq. cm. 
per min. at air vel. 
140 235 

Skin 0821 .0738 .0680 

Clothing 0502 .0437 .0380 

Hair 0534 .0463 .0392 

Shoes 0412 .0341 .0398 



Total Radiation 

Air vel. Calories per hour 

per sq. meter 

o 28.9 

140 25.2 

235 22.6 



Place 



Temperatures at Air Velocity 
140 235 



room 25.0 24.9 25.1 

wall A 25.6 25.3 25.4 

B 25.7 25.4 25.5 

C 26.8 26.6 26.8 

D 25.6 25.4 25.6 

E 25.2 24.9 25.1 

26 33.8 33.5 33.5 

100 33-4 32.6 32.9 

loi 33-2 32.4 32.5 

19a 32.0 32.7 32.3 

19 32.0 32.0 32. 1 

54 30.9 3I-0 30-7 

2 30.9 31.0 28.8 

3 31-2 29.3 29.4 

23 32-9 31-8 31-3 

22 32.8 32.3 31.2 

18 33-5 33-1 32.2 

l8a 33.0 32.8 32.0 

17 34-8 33-5 31-9 

17a 34-7 32.8 31.9 

9 31-5 31-0 307 

10 32.2 31.5 31.2 

8 30.6 29.8 30.3 

7 30-6 29.8 30.8 

26a 31.9 31. 1 30.4 

35 32.6 31.5 31.0 

36 32.7 31-8 31 -5 

29 30. 1 26.5 26.9 

30 29.8 27.8 27.4 

27 31-3 30.5 29.9 

28 31.2 31.2 30.3 

wall A 26.6 26.5 26.1 

B 26.5 26.6 26.3 

C 27. 1 27. 1 27.2 

D 25.8 26.0 26. 1 

E 25.4 25.4 25.7 

room 24.6 25.3 25.7 



NO. 6 



BODY RADIATION ALDRICH 



49 



Table E9 



Date: July 20, 1928. 

Subject: E. L. 

Sex: Female. 

Age: 8 yrs. 5 mos. 

Weight: 24 kg. 

Height: 129 cm. 

Surface Area: .94 sq. m. 

Clothing: Light, cotton dress, no 

sleeves, high socks. 
Air temperature outdoors, 32° to 35°.6. 
Relative humidity indoors, 60%. 



Temperature Summary 



Kind 



No. 
Values 



Temp, at air veL 







145 



245 



Skin 9 

Clothing. ... 13 

Hair i 

Shoes 2 

Wall 10 

Room 2 



34-9 


34-3 


34-6 


31. « 


30.8 


30.7 


33-3 


30.2 


309 


31. « 


30.5 


30.6 


27.1 


26.9 


27.2 


26.0 


26.1 


26.4 



Radiation Summary 

Calories per sq. cm. 
per min. at air vel. 
145 245 

Skin 0729 .0673 .0583 

Clothing 0430 -0352 .0320 

Hair 0567 . 0294 . 0340 

Shoes 0430 .0319 .0307 





Total 


Radiation 


Air vel. 




Calories per hour 
per sq. meter 







25.8 


145 




20.8 


245 




19.0 



Place 



Temperatures at Air 
145 



room 25.7 25.9 

wall A 26 . 6 26.4 

. B 27.1 26.5 

C 28.4 27.4 

D 26.8 26.4 

E 26.5 26.2 

26 351 34-6 

100 330 32.3 

loi 331 32.5 

19a 30.8 30.0 

19 31-6 30.7 

54 33-0 32.4 

2 31-6 30.8 

3 30.4 29.9 

23* 32.5 32.2 

22* 32.6 32.1 

18 341 33-4 

i8a 34.4 34.2 

17 34-8 33-7 

17a 35-0 33.8 

9 32.5 32.5 

10 32.6 32.3 

8 31-9 29.3 

7 31-6 31-8 

26a 33.3 30.2 

35 31-8 31-1 

36 31-8 30.7 

29 32.6 2^.1 

30 2>i.\ 28.5 

27 319 313 

28 32.1 32.1 

wall A 27.3 27. 1 

B 27.0 27. 1 

C 27.9 28.0 

D 26.8 26.9 

E 26.5 26.6 

room 26.3 26.4 



Velocity 
245 
o 
26.2 
26.6 
26.9 
27.8 
26.8 
26.6 

34-7 
330 
330 
30.2 
314 
32.5 
30.3 
30.7 
32.5 
33 o 

34- 1 
340 
33-8 
33-6 

31-4 
31-6 

30.3 
30.9 
30.9 
30.3 
31-3 
28.0 
29.2 
31-4 
31-3 
27.2 

27-5 
28.3 
27.0 

26.6 



50 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 



Table Eio 



Date: July 20, 1928. 

Subject: J. C. 

Sex: Male. 

Age: 10 yrs. 11 mos. 

Weight: 35 kg. 

Height: 135 cm. 

Surface Area: i.i4sq. m. 

Clothing: Cotton waist, golf knickers, 

high socks. 
Air temperature outdoors, 32° to 35°.6. 
Relative humidity indoors, 60%. 



Temperature Summary 



Kind 



No. 



Temp, at air vel. 



Skin 7 

Clothing. ... 15 

Hair i 

Shoes 2 

Wail 10 

Room 2 





o 

35-2 
32.8 
34-0 
32.0 
26.9 
25.8 



145 



34-8 


34- 


32.2 


31- 


34- 1 


32. 


31 9 


32. 


27,2 


27- 


26.3 


26. 



Radiation Summary 

Calories per sq. cm. 
per min. at air vel. 
145 245 

Skin 0768 . 0703 . 0664 

Clothing 0533 .0457 .0425 

Hair 0647 . 0629 . 0458 

Shoes 0462 .0431 .0451 



Total Radiation 



o 
145 
245 



Calories per hour 
per sq. meter 

30.0 
26.3 
24.4 



Place 



Temperat 




ures at Air 
145 



room 25 

wall A 26 

B 26 

C 21 

D 26 

E 26 

26 34 

100 34 

loi 33 

19a 33 

19 33 

54 33 

2 ^2 

3 31 

^Z Z?> 

22 32 

18 34 

i8a 34 

17 34 

17a 34 

9 32 

10 32 

8 Z2 

7 31 

26a 34 

35 34 

36 34 

29 32 

30 Z'2 

^1 31 

28 31 

wall A 27 

B 27 

C 27 

D 26 

E 26 

room 26 



.6 


26 


.6 


26 


■4 


26 


•4 


27 


■5 


26 


•3 


26 


•5 


34 


.0 


33 


■4 


2,2, 


■7 


2,2, 


■3 


2,2, 


■4 


22 


. 2 


22 


•9 


31 


. I 


22 


■9 


32 


.2 


22- 


.0 


34- 


. I 


33- 


.8 


33- 


.0 


30. 


•3 


22- 


. I 


22- 


•9 


31- 


.0 


34- 


. I 


31- 


•5 


22- 


I 


31- 


/ 


31- 


4 


31- 


9 


32. 


3 


27. 





27- 


8 


28. 


8 


27. 


7 


26. 





26. 



Velocity 

245 
o 

26.5 

26.9 

27.2 

28.0 
27.0 
26.9 
33-9 
33-5 
33-4 
33 I 
33-3 
340 
30.8 
32.2 
32.8 
32.5 
33- 1 
22-7 
33-6 

22-7 
31.0 

317 
31-8 

22-7 
22-2 
32.8 
32.0 
30.2 
30.1 
30 -9 
31-4 
27.2 

27-5 
28.1 
27. 1 
27. 1 
27.0 



NO. 6 



BODY RADIATION ALDRICH 



51 



Table F. — Summary of Cloth-covered Calorimeter Tests 

Calorimeter Wall Air ^_Percent Ra diated by 

^gjj^p Vel. Melik. Thermoelement 

Preliminary tests — 

Vertical Estimated o «o 7/ 

Horizontal Estimated o 74 "5 

Final tests with cloth walls— 

Vertical Measured o 61 «" 

Vertical Measured 75 39 4^ 

Vertical Measured 130 4i 35 

Vertical Measured 190 40 25 



No. of 
Tests 



Table G.-Summary Comparing all Thermoelement Temperatures tvith Cor- 
responding Temperatures Computed from Melikeron Values Gwen m 
Tables B, C and D 



Place 

Skin 

Clothing 

Hair 

Shoes 

Wall 

Cloth-covered 
Cal. in still 
air 

moving air 
< 130 ft... 
> 190 ft... 

Clothing] 

Hair [... 

Shoes J 

! Clothing 
Hair 
Shoes 
Cal. < 130 ft. 



No. of 
Observations 

37 

49 

9 



15 



52 

16 
12 

67 



135 



Average difference 
Melik. — Thermo. 



•91 
.12 

•30 

•39 
• 03 



.56 

•37 
2.8 

I. ID 



.80 



Average difference 
Room temp. — Water Jacket temp. 




.82 

— •4 
.2 

1. 12 



.82 



rithmet 
Mean 








3i 




•45 




.61 




.20 




•37 



•95 

-7 
1.6 

1.40 
1. 14 



52 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 



Table H. — Summary Taken from Observations Recorded in Table E 



Subject 


Room 


Wall 


Radiation Loss 




Temp. 


Temp. 


large calories 

per hour per 

sq. meter 


In still air — 








o 







S. A. 


19.8 


21 .1 


38.6 


S. W. 


251 


26.0 


29-3 


M. W. 


24-5 


25-7 


31.0 


T. L. 


22.5 


23.8 


32.5 


P. L. 


24.1 


25.2 


29.0 


M. A. 


24.0 


25-5 


28.0 


M. B. 


24.6 


25.6 


28.1 


G. B. 


24.8 


26.0 


28.9 


E. L. 


26.0 


27.1 


25-8 


J. c. 


25.8 


26.9 


30.0 


Air vel. 


<50 ft.— 






s. w. 


233 


245 


34-4 


M. W. 


23.2 


24-5 


34-2 


Air vel. 


50 to 100 ft.- 


- 




s. w. 


23.1 


239 


32.1 


M. W. 


23.2 


24.2 


30.2 


T. L. 


22.7 


23-5 


30.2 


P. L. 


24-3 


25-1 


27.4 


M. A. 


24.2 


253 


26.8 


Air vel. 


100 to 150 ft 


— 




S. A. 


21.3 


22.4 


29.4 


T. L. 


22.8 


23.2 


29.7 


M. B. 


24.9 


25.8 


25.2 


G. B. 


251 


25-9 


25.2 


E. L. 


26.1 


26.9 


20.8 


J.C. 


26.3 


27.2 


26.3 


Air vel. 


180 to 250 ft 


- 




S. A. 


20.9 


21.3 


27.2 


P. L. 


24.6 


25 -.5 


21.4 


M. A. 


24.6 


25-3 


25.2 


M. B. 


25.2 


25-9 


23.1 


G. B. 


25-4 


26.0 


22.6 


E. L. 


26.4 


27.2 


19.0 


J.C. 


26.7 


27-3 


24.4 



Means- 



Air 
Vel. 


No. of 
Deter- 
mina- 
tions 


Room 
Temp. 


Wall 
Temp. 


Radiation 
Loss, large 
cal. per hr. 
per sq. m. 


<50 

50 to 

100 

100 to 


12 

5 


239 

23-5 


25.2 
24.4 


30.7 
29 -3 


150 

180 to 


6 


24.4 


25.2 


25-7 


250 


7 


24.8 


25-5 


23.2 



NO. 6 



BODY RADIATION — ALDRICH 



53 



Table J. — ■Summary from Observations Given in Table E, for Still Air 





















Basal 


Loss by- 




















Room 




Metab. 


Radiation 

A 






(large cal 


per sq. m. 


Rad. Loss 


1928 


Subject 


Age 




Sex 






Temp. 




per 


tiour) 


Basal Met. 


May 30 


S. A. 


7 




M 






I9?8 




43 


38.6 


.90 


July 12 


s. w. 


6 




M 






25-1 




44 


293 




67 


July 12 


M. W. 


II 




F 






24-5 




40 


31.0 




77 


July 14 


T. L. 


14 




M 






22.5 




41 


32.5 




79 


July 18 


P. L. 


8 




F 






24.1 




41 


29.0 




71 


July 18 


M. A. 


55 




F 






24.0 




34 


28.0 




82 


July 19 


M. B. 


5 




F 






24.6 




42 


28.1 




67 


July 19 


G. B. 


30 




F 






24.8 




35 


28.9 




83 


July 20 


E. L. 


8 




F 






26.0 




42 


25.8 




61 


July 20 


J.C. 


II 




M 






25.8 




42 


30.0 




71 


Arranged according 


to 


increasing i 


-00m temperatures: 
















Room 


Radiation Loss 










Subject 




Temp. 


Basal Metabolism 








s. 


A. 




19 


8 




90 












T. 


L. 




22 


5 




79 


■ .84 










M 


A. 




24 







82, 












P. 


L. 




24 


I 




71 












M 


W. 




24 


5 




77 


, -74 










M 


B. 




24 


6 




67 


\ 










G. 


B. 




24 


8 




83. 












S. 


W. 




25 


I 




67 












J. 


C. 




25 


8 




71 


' .66 










E. 


L. 




26 







61 











54 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 



Table K. — ■Summary of Drop in Temperature of Skin and Clothing due to Increased 
Air Motion, from Observations Given in Table E 

{Each number is the mean of from 3 to 6 values) 









Sk 


n 




Air Vel. 


Awav from 


Towards 


Subject 


(Feet per min.) 


fan 


fan 




S. A. 


loo to 150 


— r-7 


—1-5 




180 to 250 


— 2 


9 


— 2. 1 


s. w. 


to 50 


— 


2 


— 9 




50 to 100 


— 


6 


— I .0 


M. W. 


to 50 


— 


2 


+ -4 




50 to 100 


— 


9 


—1.8 


T. L. 


50 to 100 


— 


7 


— -9 




100 to 150 


— I 


8 


—2-9 


P. L. 


50 to 100 


+ 


4 


— . I 




180 to 250 


— 


3 


— 1 .2 


M. A. 


50 to 100 


— 


6 


— 1 .0 




180 to 250 


— 


8 


— 1 .2 


M. B. 


100 to 150 


+ 


7 


— .6 




180 to 250 


+ 1 





+ -3 


G. B. 


100 to 150 


— 


5 


—13 




180 to 250 


— 


8 


—2.4 


E. L. 


roo to 150 


— 


5 


—1.8 




180 to 250 


— 


I 


—1.6 


J. c. 


TOO to 150 


— 


2 


— -5 




180 to 250 


■ — 


7 


— I . I 



Side 



+ -5 



+ 



Clothing 

Away from Towards 

fan fan 


— I . I 


— 1.9 


-1-5 

+ .2 
— .8 


—39 
— -9 

—2.8 


— 1 .2 


— . I 


—1.6 


—1-7 


— -3 


+ .1 


— 1-4 
• — 2.2 
— 1 .2 


— -3 


+ .8 

— .6 


—1-7 

— .8 
—1.8 

— .6 





-1-5 


— .2 


—1.4 


— -7 


—1.8 


— -7 

— -5 

— -3 

— .2 


—1-7 
—r-7 
— -9 
—1.6 



+ 



+ 



Means- 



to 50 

50 to 100 

100 to 150 

180 to 250 


- .2 

"~ -5 

- -7 

- 7 


— .2 

— 1 .0 .... 

—1.4 

—1.3 


— -5 

— .6 

— -5 

— -3 


— -5 
—1.6 

— r-5 
— 2.0 


— -4 

— -5 

— 4 

— -7 


to 100 
100 to 250 


- -4 

- -7 


— .8 

— 1 .2 .... 


— .6 

— -4 


— r-3 
—1-7 


— -5 

— -5 




. 




•11 ■ 







From Table H, Mean change in Room Temp, from still air to air motion = +°.2. 
Mean change in Wall Temp, from still air to air motion = — °.2. 



Table L. — Summary of the Ttvo Series of Ten Subjects (Tables B and E) 





Dates 


Range 

of 
Room 

T. 


Mean 

of 
Room 

T. 


Range of 
Relative 
Humidity 


Mean 


Kind 


Total 
Radia- 
tion 


Basal 
Metab- 
olism 


Radia- 
tion 




Bas. 
Met. 


First 
Second 


Dec. 9 

to 
Feb. II 

May 30 

to 
July 20 


i8°4 

to 

22.6 

19.8 

to 

26.0 


21°3 
24.1 


•2-7 or 
32 /O 

to 

59% 

56% 

to 
68% 


43% 
62% 


Adult 

Children 

All 

Adult 

Children 

All 


35-2 
32.7 

33-5 

28.4 

30.5 
30.1 


39 
43 

42 

34-5 
42 

40.5 


.90 

.76 
.80 

.82 

■73 
-75 



Radiation and basal metabolism values are given in large calories per hour 
per sq. meter of body surface. 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 

VOLUME 81. NUMBER 7 



RECENT ARCHEOLOGICAL DEVELOP- 
MENTS IN THE VICINITY OF 
EL PASO, TEXAS 



(With Five Plates) 



BY 

FRANK H. H. ROBERTS. JR. 

Bureau of American Ethnology 




(Publication 3009) 



CITY OF WASHINGTON 

PUBLISHED BY THE SMITHSONIAN INSTITUTION 

JANUARY 25, 1929 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 

VOLUME 81, NUMBER 7 



RECENT ARCHEOLOGICAL DEVELOP- 
MENTS IN THE VICINITY OF 
EL PASO, TEXAS 



;WiTH Five Plates] 



BY 
FRANK H. H. ROBERTS, JR. 

Bureau of American Ethnology 




(Publication 3009) 



CITY OF WASHINGTON 

PUBLISHED BY THE SMITHSONIAN INSTITUTION 

JANUARY 25, 1929 



BALTIMORE, MD., O. 8. A. 



' I 



\- 



.y^%'r$- 





2 < 






P CU 



o 



RECENT ARCHEOLOGICAL DEVELOPMENTS IN THE 
VICINITY OF EL PASO, TEXAS 

By frank H. H. ROBERTS, JR. 

bureau of american ethnology 

(With Five Plates) 

In the winter of 192 1 the writer visited a number of caves approxi- 
mately 20 miles northeast of El Paso, Texas, for the purpose of 
examining a series of pictographs which were painted on their walls. 
The mountains in which the caves are located lie between El Paso 
and the far famed Hueco Tanks, in the range bearing the same name, 
which played so prominent a part in the early history of that section 
of the Southwest. These water holes formed the oasis for many a 
wandering band of Apaches, and have long been the rendezvous of 
cattlemen and a resting place for travellers in that semi-desert region. 
There is a much greater variety and number of pictographs in the 
vicinity of the tanks than in the immediate neighborhood of the caves 
mentioned above, but the drawings in the latter are of greater interest, 
not for what they represent but because their presence led to the dis- 
covery that the caves were once occupied and that many objects of 
the material culture of a people not yet definitely identified were 
buried beneath the sand which covered the floors and filled the back 
portions of the recesses. 

At the time of his first visit to the region the writer was impressed 
with the possibility of finding traces of occupation in the caves, but 
he was unable to make the necessary investigations because of lack 
of time and equipment. In the following years there was no oppor- 
tunity to return to the region, and consequently no definite steps could 
be taken towards a careful examination of the caves. In the mean- 
time others became cognizant of their existence, through the reports 
that paintings were to be seen on the rocks of the neighborhood, and 
it was soon discovered that interesting " curios " could be dug out 
of their sandy floors. No extensive finds were made, however, until 
the spring of 1927 when Mr. Robert P. Anderson, then president 
of the El Paso Archaeological Society, and Mr. R. W. Stafford 
began a systematic exploration of the caverns and secured a large 
amount of material. 

Smithsonian Miscellaneous Collections, Vol. 81, No. 7 



2 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

The specimens collected during the investigations of the two El 
Paso men include fragments from headdresses, a number of sandals, 
curved clubs, digging sticks, spear shafts, spear heads, foreshafts for 
spears, netting, a cord skirt, shell pendants, beads, parts of mosaic 
combs, and a large basketry armlet covered with a turquoise mosaic. 
News of the discoveries was published in El Paso papers and was 
reported to the National Museum by Mr. Anderson. The writer was 
just leaving for field-work in northwestern New Mexico when this 
information was received, and fortunately was able to include El Paso 
in his trip west. At the latter place he had an opportunity of examin- 
ing the objects gathered by Mr. Stafford and Mr. Anderson and of 
revisiting the caves where they were found. 

There are 28 of these natural recesses in the faces of the limestone 
cliffs. In some cases they are just above the tops of the steep talus 
slopes, about two-thirds of the way up the side of the mountain, and 
in many instances have a narrow ledge of rock running along in front 
of them (pi. i). Others are located just below the tops of the cliffs 
along the upper ledges. In general they open to the northwest or 
west, and most of them contain evidence of Indian visitors. In many 
these traces take the form of pictographs painted on the walls in 
red pigment, while others furnish objects from the material culture 
of the people. The best examples of the rock paintings were not found 
in the caves where objects were obtained, but in a large shallow recess 
about a mile away. Some of the caves have small alcoves, opening 
off from the main room, which give evidence of having been blocked 
up at some time or other with loose rock walls. 

In three of the caves, smoke-blackened ceilings and debris-covered 
floors gave definite indications of at least temporary occupation. It 
was in the layers of refuse, ash, and sand that the specimens left by 
the people who occupied them were found. One cave in particular had 
proved quite rich in svich objects. At the time when it was visited 
it had been rather thoroughly examined and a great many objects 
removed. By digging in the few undisturbed portions of the floor 
at the back of the cave, however, there were uncovered 12 sandals, a 
number of spear shafts, a fragment of netting, several portions of 
curved clubs, a few beads, and some potsherds. 

The pictographs in this district consist of realistic and conven- 
tionalized life-forms and geometric designs. Inasmuch as a careful 
study of the drawings and paintings on the rocks of the region is being 
made by Col. M. L. Crimmins, U. S. A., retired, only a few examples 
will be given. The writer feels that a great majority of them are to 
be attributed to the various groups of Apache who were in that section 



NO. 7 ARCHEOLOGICAL DEVELOPMENTS IN TEXAS ROBERTS 3 

of the Southwest in fairly large numbers, but a few of them suggest 
at least slight Pueblo influence. The latter seem to be of greater age 
and in some instances are partially covered by portions of those of 
more recent date. Whether they have any relation to the objects 
found in the caves is a problem still to be solved. 

Three figures which probably were intended to represent masked 
heads were found on the walls of one of the caves (fig. i). In two 
examples the persons represented seem to have been wearing a tablet- 
like headdress, a feature quite common in the Southwest since early 
historic times. Thus far no evidence has been obtained to show that 
the ceremonial mask was in use in prehistoric times, although certain 
investigators are inclined to believe that its development may have 
begun, as the result of influences from the Mexican cultures to the 






Fig. I. — Representations of masked heads painted on walls of one of the caves. 

south, in the period just foUow^ing the great era of the Pueblo peoples 
and immediately preceding the advent of the Spanish explorers. The 
use of the ceremonial headdress has been markedly widespread in 
recent times, however, not only among the Pueblos and Navajos but 
also among the Apaches in certain of their observances. Among the 
majority of the groups using the mask and headdress there is con- 
siderable use of thin strips cut from the flowering stem of the yucca 
or Spanish bayonet in building up the framework. Fragments of 
frames made from this sort of material were found in several of the 
caves, and it seems quite probable that the pictures represent such 
objects. Their stepped or terraced shape is comparable to some 
of the Pueblo forms. The third figure possibly represents the mask 
worn by a participant in a bufTalo or similar dance and is cer- 
tainly decidedly suggestive, in its character and the manner in which 
it was drawn, of the work of the nomadic Indians. 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOL. 



Among the realistic forms are a number of birds which are not 
readily identifiable. Two examples are illustrated in figure 2, a, b. 
There are also many representations of snakes. In some instances, 
as figure 2, c, they are very realistic, while in others they are more 
conventionalized and show a combination of the geometric and realistic 
types. The horned or plumed serpent illustrated in figure 2, d, is an 
example. The plumed serpent has long played a prominent part in 
Southwestern cultures and representations of it are found in many 
places. It occurs in the decorations on pottery and in pictographs and 
petroglyphs, and is used in efiigy forms in certain ceremonies of the 
Zufii and Hopi Indians. Its prominence in the art and ceremonies of 
the Mexican cultures to the south is so well known that it needs no 






Fig. 2. — Bird and serpent pictographs found on cave walls. 

discussion. The example from this cave suggests similar forms on 
pottery from Casas Grandes in the Chihuahua district of Old Mexico 
and also some of those occurring on bowls from the Mimbres Valley 
in southern New Mexico. 

Figure 3 shows the best example of a highly conventionalized geo- 
metric form. It is impossible to say just what it was intended to 
represent, but it is quite reminiscent of some of the square-shouldered 
figures of the Pueblo country to the north and west. A closer parallel 
to this figure is to be found, however, in some of the geometric 
designs on pottery from Casas Grandes in northern Mexico. 

Only a few illustrations of the kind of pictographs to be seen in 
this section have been given, but they are sufficient to indicate the 
general character of the paintings ; an extended discussion would be 
beyond the requirements of this paper. 



NO. 7 ARCHEOLOGICAL DEVELOPMENTS IN TEXAS ROBERTS 5 

Mention has been made of headdresses fashioned from the split 
stems of the yucca. Several triangular shaped objects were found in 
some of the caves by Mr. Stafford and Mr. Anderson which may well 
have been the framework for such headdresses. They were constructed 
from two long pieces and a series of short ones placed cross-wise (fig. 
4). The short cross pieces were fastened to the longer ones by means 
of cord made from tightly twisted yucca fiber. The holes through which 
the cord passed were drilled. In some cases the material was painted 
red on one side and the other side was covered with pitch, possibly 




Fig. 3. — Conventionalized geometric figure painted on the wall of a cave. 



for the attachment of down or feathers ; other examples show that 
the red pigment was applied to both sides. Some of these triangular 
frames measured 8 inches wide and i8 inches long while others were 
as much as 2 feet wide at the base and 3 feet long. They would have 
served admirably, because of their extremely light weight, as a base 
for a pyramidal or fan-shaped headdress. 

Two kinds of sandals appear in the collections from these caves. 
The predominant style is not common in the better known portions of 
the Southwest, whereas the other form is fairly well represented in 
collections from various sites (pi. 2). Both were made from the 
ever-useful yucca leaves woven in a wickerwork technique. The 



6 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

narrow leaf variety of the plant seems to have furnished the best 
material as it was the most frequently used. 

The characteristic form of sandal has a long oval outline, and seems 
to have been shaped for use on either foot. It was made of a wicker- 
work of whole leaves woven over a warp of two bundles formed 
from several of the leaves, four to eight being the normal number. 
The warp was generally tied at both ends, although occasional 
examples show a single bundle bent at the middle and tied at the heel 
end. The latter are generally rather square toed. The projecting ends 
of the warp leaves were frequently shredded at the heel to form a 
pad, and at the toe, several of them were tied to make a fastening loop 
and the remainder were allowed to protrude to form a slight fringe. 
The weft strands or cross-elements were started on the lower surface 




Fig. 4. — Characteristic form in which headdress frames were made 
from yucca stalks. 

of the sandal (fig. 5). The small ends meet in the middle along the 
top ; the strands pass under one warp and back over it ; then under 
and over the other, the ends being drawn down through the sole where 
they were cut off and shredded to form a pad on the bottom. This 
is one form of the figure 8 type of weaving. 

Two methods of fastening the foot strings at the toe end are indi- 
cated by the specimens. The loop fashioned from projecting ends 
of the warp leaves has already been mentioned. Another form shows 
a separate' loop passed through the warp. In some of the sandals, 
strings of twisted fiber were fastened to these loops and passed back 
over the foot where they were attached to the warp, one string just 
back of the instep and the other just below the ankle. The loops in 
both forms were small and the strings probably passed between the 
first and second and third and fourth toes. On most of the specimens 
found bv the writer, and those examined in other collections, there 




u 



2 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOL. 81, NO. 7, PL. 3 




Si>car .sliafts showing tiber embellishment, l^ S. National Museui 
Catalogue No. 340790. 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOL. 81, NO. 7, PL. 4 




Mc. I. — Cord skirt made from twisted apocynum 
fiber. Photograph by J. A. Alexander. 



^.-a^^^^^.- 











- - .<- 



' ,/ ^^^ -. .. ! 






']!?._• 



Fig. 2. — Fragment of netting found in one of the caves. 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOL. 81, NO. 7, PL. 5 




'iG. I. — Raskftry aniili't with tur(|U()isc mosaic. 




Fk;. 2. — Shell pendants and fragnien.ts from mosaic combs. 
Photographs by ]. A. Alexander. 



NO. 7 ARCHEOLOGICAL DEVELOPMENTS IN TEXAS ROBERTS 7 




Fig. 5. — Technique of sandal weaving. 




Fig. 6. — Attachment cords on sandals. 



8 SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOL. 



are no indications of heel cords, but in a few instances they are 
present. Where this is the case, the heel cords consist of several 
loops of shredded leaves which pass around the back of the heel 
of the wearer and connect the side strings (fig. 6). 

In general it may be said that this form of sandal is one which 
belongs in that section of the Southwest. Similar specimens have 
been reported from Silver City,'' New Mexico ; the writer has seen 
a number in various collections from caves in the vicinity of Van 
Horn. Texas, some distance east of El Paso ; and two of the same 
type, in the collections of the National Museum,^ were found in a 
cave near Lava, New Mexico, in 1902 and presented to the museum 
shortly afterwards. Dr. Walter Hough found a specimen in 1905, 
during the course of his investigations at Tularosa Cave in western 
New Mexico, which is comparable to those from El Paso, although 
the yucca leaves in the former were partially shredded.^ Another of 
the same type is figured by Lumholtz in his Unknown Mexico. This 
specimen was obtained during the course of investigations carried on 
in Cave A^alley, northwestern Chihuahua.' Only one example of the 
type has been noted in collections coming from regions farther north 
in the Pueblo area. The latter is in the private collection of Mr. J. A. 
Jeancon at Nateso Pueblo, Indian Hills, Colorado. Mr. Jeancon 
found it in a cave in southeastern Utah in 1908, when he was con- 
ducting explorations in the Montezuma Creek section. A type very 
suggestive of the El Paso form but varying somewhat in the technique 
of its manufacture was found in northeastern Arizona by Kidder and 
Guernsey during their earlier explorations. They found a number of 
sandals in a small cliff house on Laguna Creek which have the general 
appearance of the ones from El Paso but which differ from them in 
that they did not have the figure 8 weave in the weft and that they 
had only a single leaf in the warp.° 

The second form of sandal had four warp strands of single leaves. 
The warps were tied at the heel and toe, and the weft leaves were 



^ ]\Iason, O. T., Primitive Travel and Transportation. Rep. U. S. Nat. Mus. 
1894, Washington, 1896, p. 358, pi. 7, No. 3. U. S. Nat. AIus. Cat. No. 456ro. 

'U. S. Nat. Mus. Cat. No. 215428. 

^ Hough, W., Culture of the Ancient Pueblos of the Upper Gila River region, 
New Mexico and Arizona, Bull. 87, U. S. Nat. Mus., Washington, 1914, p. 84, 
fig. 173, a- U. S. Nat. Mus. Cat. No. 246688. 

■* Lumholtz, Carl, Unknown Mexico, Scribners, 1902, Vol. i, pp. 68-69. 

° Kidder, A. V., and Guernsey. S. J., Archeological Explorations in North- 
eastern Arizona. Bull. 65, Bur. Amer. Ethnol., Washington, 1919, p. 103, fig. T,y, 



NO. 7 ARCHEOLOGICAL DEVELOPMENTS IN TEXAS ROBERTS 9 

woven back and forth in the usual wickerwork technique. The large 
ends of the weft leaves were brought out on the under side where 
they were shredded as in the case of the other sandal. There was 
also the same tendency to permit the shredded ends of the warp leaves 
to protrude in a sort of fringe at the toe. No specimens from this 
region have been found with foot attachments still in place, and it is 
therefore impossible to tell how these may have functioned. Similar 
sandals have been found at other sites in the Southwest. Kidder and 
Guernsey describe the form in their Arizona paper/ and the collection 
obtained from Bat Cave, 125 miles north of El Paso, by Mr. DeMeir 
contains an example of the form.^ 

The spear shafts are very interesting (pi. 3). They were made 
from the flower stalks of the agave, which, although light, is 
very strong and suitable for such purposes. Their average length 
varies between 5 feet 3 inches and 5 feet 9 inches. The distal ends 
of these shafts are the heaviest. They have an average diameter of 
one-half inch and taper gradually towards the butt ends. The latter 
average a little less than a quarter of an inch in diameter. In the 
heavy ends a cone-shaped hole was drilled for the purpose of insert- 
ing a short foreshaft in which a stone point had been mounted. They 
were not always equipped with stone points, however, as some of 
the specimens in the collection of Mr. Stafford had hard, sharp wooden 
points. In every case the proximal or butt end shows a slight cup- 
shaped depression, which suggests that the shafts were for use with a 
spear-thrower or atlatl. The latter object has a small hook at one 
end which would fit into such a cup-like hole and aid materially in 
hurling the projectile. The ends of the shafts were bound with sinew 
wrappings which have disappeared from most of the specimens, al- 
though the markings which they left are plainly discernible. These 
wrappings were probably used to prevent the shaft from splitting 
as a result of the drilling of the hole in its end. 

One rather curious feature about the spears is that they were 
decorated with streamers, balls, and braids of agave fiber {Agave 
Icchegnilla Torr).^ These decorations must have been attached for 
ceremonial purposes, as the spears could not have been of great use- 
fulness with so much cumbersome material fastened to them (pi. 3). 
It is possible that they may have been used as wands in the ob- 



^ Idem, p. 158. 

'U. S. Nat. Mus. Cat. No. 215428. 

^ Mr. L. H. Dewey of the U. S. Department of Agriculture kindly identified 
the material for the writer. 



lO SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

servance of some ceremony, or they may be analogous to the long- 
prayer pahos of the Pueblos. Certain features about the cave in which 
they were found suggested that it might have been one of the sacred 
places of the people rather than a mere dwelling site. The great 
numbers of spear shafts scattered through the debris give at least 
some grounds for such a supposition. 

Closely associated with the twisted fiber on the shafts, in a number 
of cases, was a small bundle of three or more sticks which had been 
carefully smoothed, sharpened at one end, and rounded off at the 
other (fig. 7). They were bound together by strips of sinew and 
then fastened to the shaft with some of the twisted fiber. They were 
so placed that their rounded ends projected several inches beyond the 
butt of the shaft. What their purpose may have been or what signifi- 
cance may be attached to them is not known at the present time. 
Kidder and Guernsey found similar bundles of small sticks in their 




Fig. 7. — Method of attaching bundle of small sticks to end of spear shaft. 

Basket Maker caves which they identified as material for the making 
of hair ornaments.^ They did not find any attached to spear shafts. 

A dull red pigment was applied to the spear shafts in some cases, 
and this is especially noticeable where they have been protected by 
fiber wrappings. The shafts as a group are very much like those 
found with the remains of the Basket Maker cultures in the region 
farther west and north. Their chief difirerence is in the agave fiber 
embellishments. 

Foreshafts for the spears were made from sticks of harder material. 
They were tapered at one end to fit the socket in the shaft, while the 
other end was notched for the insertion of a stone point. The latter 
was held in position by the use of pitch and a wrapping of sinew. 
Without the heads the foreshafts range from 6? to 7 inches in length. 
The stone points, from i to 2 inches in length, are of the elongated 
triangular shape with good barbs and a tang. The majority of them 
were made from a gray chert. 



* Guernsey, S. J., and Kidder, A. V., Basket-Maker Caves of Northeastern 
Arizona. Papers of the Peabody [Museum, \'ol. \'III. No. 2, Cambridge, 1921, 
p. 52, pi. 18, c. 



NO. 7 ARCHEOLOGICAL DEVELOPMENTS IN TEXAS ROBERTS II 

The piece of netting obtained from the cave ^ is too small to permit 
the determination of what it may have been used for, but because 
of the many similar fragments which were dug out by various speci- 
men hunters it is possible that it may have been a small section 
from a rabbit net such as the peoples in the Pueblo area farther north 
and west used/ It is different from the latter in its weave, however, 
and is quite suggestive in a general way of the technique used in the 
manufacture of the foundations for the fur and feather cloth blankets. 
In the latter the weaving was much finer than that of the El Paso 
specimens, which give no indication of the attachment of either fur 
or feathers. The fragment may possibly be from a carrying net. 

The netting was simply made, although two kinds of material were 
used in its manufacture. Double warp threads of tightly twisted, two- 
ply apocynum cord are in marked contrast to the weft of loosely 
twisted agave fiber. The weft was held in place by a double twist 
of the warp between each weft cord (pi. 4, fig. 2). The weft was 
looped back at the edge and carried along until its end was reached, 
when a new cord was spliced on. The warp strings were placed at an 
average of every two inches. The double twist which held the weft in 
place made an average space of one- fourth inch between the strands 
of the latter. The width of the fragment obtained by the writer is 
20 inches but its original length cannot be determined. Netting of the 
same type was found in caves near Carlsbad, New Mexico, and a 
portion of it presented to the National Museimi.^ 

Twisted apocynum fiber was used for other purposes than making 
netting and cords for sandal ties. One of the specimens from the 
large cave was a cord apron consisting of a waist string to which a 
series of short cords had been attached (pi. 4, fig. i). The latter 
hung down in front in a kind of fringe. Kidder and Guernsey, as 
well as many other investigators, have found large numbers of similar 
aprons and have determined that they were a woman's garment. Many 
have been found on female mummies but none has been observed 
on a male. 

Curved clubs from the caves are comparable to those from the 
Basket Maker caves of northeastern Arizona and to some of those 
found in southeastern Utah bv Mr. N. AI. Judd." Thev were fashioned 



'U. S. Nat. Mus. Cat. No. 340797- 

' Guernsey and Kidder, he. cit., p. 77, pi. 31, c. 

* U. S. Nat. Mus. Cat. No. 330643- 

* Guernsey and Kidder, loc. cit., p. 88, pi. 36. 

Judd, N. M., Archeological Observations North of the Rio Colorado. Bull. 
82, Bur. Amer. Ethnol., Washington, 1926, p. 147, pi. 51. 



12 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOL. 8l 



from a hard wood and are slightly oval in cross-section. The sides 
are fairly flat but the edges are well rounded. The long way of the 
stick is not straight. They are either slightly crescentic like a boom- 
erang or tend towards an S-shape (fig. 8). Down the center on each 
side, running from end to end. are four deep parallel grooves. These 
are not always continuous and may be broken at one or two places. 
Possibly this is due to the fact that at intervals of varying distance 
most of the clubs have, or did have, encircling wrappings of sinew, 
probably so placed to prevent the object from cracking. The makers 
occasionally went so far as to make a groove around the stick where 
these wrappings were placed. Some have a deeper groove or notch at 
one end which may have been for the purpose of attaching a wrist 
cord. Practically all show traces of a pitch bumper at the opposite 
end from the cord notch. 





Fig. 8. — Two forms of grooved clubs found in the caves. (About f natural size.) 

Such clubs are frequently referred to as rabbit sticks, because of 
their apparent likeness to clubs used by some of the modern south- 
western Indians in hunting rabbits, but in certain specific features they 
are not comparable to them. Inasmuch as this subject has been dis- 
cussed at some length elsewhere,' it will not be necessary to consider 
it in detail here. Guernsey and Kidder have pointed out the relation 
between clubs of this sort and the atlatl in the Basket Maker cultures, 
and also as noted in some of the sculptures of Yucatan, in which 
figures are depicted holding such an implement as well as bundles of 
spears and spear-throwers. It is in this connection that the suggestion 
was made that they may have been used as a weapon of defense in 
warding off spears. They would also have made a fairly good offensive 
weapon at close quarters for delivering a bruising or crushing blow. 

Clubs of the same kind have been found at other localities in the 
El Paso area. An almost identical one was recovered from a cave 
near Carlsbad, New Mexico, in 1924 by Dr. Willis T. Lee and is at 



^ Guernsey and Kidder, loc. cit., pp. 88-89. 



NO. 7 ARCHEOLOGICAL DEVELOPMENTS IN TEXAS ROBERTS I3 

present in the U. S. National Museum." It was collected at the same 
time as the netting mentioned in a previous paragraph. Another fine 
specimen is that figured by Dr. Hough in his Upper Gila paper.' 
Mr. De Meir of Las Cruces found it at the same time as the sandals 
already described. Still another example was found in New Mexico, 
in an old shrine near Laguna pueblo, by Dr. Elsie Clews Parsons.^ 
It probably was never used at Laguna, but likely was found in some 
cave and because of the fact that it belonged to the " old " people, 
was deposited in the war god shrine as an offering of considerable 
significance. 

The few planting sticks found in the caves are very simple in form. 
They consist of a long, straight stick of hard wood slightly flattened 
and pointed at one end. There is nothing unusual in this type of im- 
plement and its only interest here lies in showing that the people 
were at least partially agriculturists. 

One of the most attractive specimens in Mr. Stafford's collection ^ 
is the basketry armlet. The base was made of basketry upon which 
was placed a rather crude mosaic of turquoise chips (pi. 5, fig. i). 
Several of the latter had been used as pendants, or at least intended 
for such a purpose, as they were perforated at one end for suspension. 
The pieces of turquoise were held in place by a thick layer of pitch, 
possibly pinon gum. 

The abalone shell pendants and fragments from two combs with 
shell mosaic ornamentation are illustrated in plate 5, figure 2. The 
combs were made from wood, and as in the case of the armlet, the 
mosaic pieces were held in position by some pitchy substance. 

Beads from the locality are of several kinds. Some were made 
from turquoise, a few from bone, others from shell, olivella, abalone 
and clam ; a few were made from seeds, and quite a number from a 
fairly hard, fine-grained white stone suggestive of the southwestern 
form of alabaster. Most of the beads, excepting of course the olivella 
shells, are of the flat cylindrical shape but an occasional one is found 
which has an elongated oval form with the perforation at one end. 
The latter might even be classed as small pendants. 



' U. S. Nat. Mus. Cat. No. 330644. 

' Hough, W., Culture of the Ancient Pueblos of the upper Gila River Region, 
New Mexico and Arizona. Bull. 87, U. S. Nat. Mus., Washington, 1914, p. 19, 
%. 21. 

U. S. Nat. AIus. Cat. No. 215429. 

' Parsons, E. C, War God Shrines of Laguna and Zuni. Amer. Anthrop., 
N. S., Vol. 20, No. 4, Lancaster, 1918, p. 385, fig. 39. 

■"The collection has since been sold to Mr. and Mrs. R. B. Alves, EI Paso, 
Texas. 



14 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

The few fragments of pottery picked up were interesting because 
they are from a type of vessel which seems t^ center, more or less, in 
the El Paso area. It is a very sandy, dark red ware with a dull black 
painted decoration. The writer has found fragments from vessels of 
the same kind at many sites in the neighborhood of El Paso, and has 
seen sherds and vessels of the same type from the ^Nlimbres Valley 
in southwestern New Mexico. There seems to be no question but 
that it is prehistoric pottery and that it belongs in the period of the 
great era in Pueblo development, but its extent — the area of its dis- 
tribution — is a problem still to be worked out. 

This brief description of the caves and the objects from them is 
not intended to be in any sense an exhaustive or complete report on 
a new archeological phase in the Southwest, but is presented purely as 
an announcement of recent developments in the area. There are 
puzzling problems which can be solved only by additional work in the 
region. Many features indicate a culture comparable to that of the 
Basket Makers, the predecessors of the Pueblo-Clifif-Dweller peoples 
of the San Juan region. This is especially marked in the spear shafts, 
curved clubs, sandals, and netting. Other factors point toward a later 
period and a possible connection with some of the nomadic groups 
of the region. Unquestionably there is some mixture of early and late 
material in these sites but unfortunately the stratigraphic evidence was 
lost during the excavations. From what could be learned of the posi- 
tions in which the objects were buried, it seems fairly certain that the 
potsherds and triangular-shaped frames which are thought to have 
been used in the making of ceremonial headdresses do not belong 
with the other objects but represent a later horizon. Of this we cannot 
be sure, however, until further investigations bring more evidence to 
light. 

On the present meager evidence the writer is inclined to suggest 
that there is in this section of the Southwest the northern fringes of a 
culture analogous to the Basket Makers of the San Juan, but which 
had its fullest development in the northern Mexico region ; a culture 
closely related to that represented by the material from the Coahuila 
caves. The sites as a whole open up a new and interesting field for 
future investigation, one which should be carefully worked, not only 
that a thorough knowledge of the remains of the region may be 
obtained, but that the relationships existing between the peoples of 
this area and those to the north and south mav be determined. 



I 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 

VOLUME 81, NUMBER 8 



PARASITES AND THE AID THEY GIVE IN 
PROBLEMS OF TAXONOMY, GEO- 
GRAPHICAL DISTRIBUTION, 
AND PALEOGEOGRAPHY 



BY 

MAYNARD M. METGALF 
The Johns Hopkins University 





^tB , 2929 



(Publication 3010) 



CITY OF WASHINGTON 

PUBLISHED BY THE SMITHSONIAN INSTITUTION 

FEBRUARY 28, 1929 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 

VOLUME SI. NUMBER 8 



PARASITES AND THE AID THEY GIVE IN 
PROBLEMS OE TAXONOMY, GEO- 
GRAPHICAL DISTRIBUTION, 
AND PALEOGEOGRAPHY 



BY 

MAYNARD M. METGALF 

The Johns Hopkins University 




(Publication 3010) 



CITY OF WASHINGTON 

PUBLISHED BY THE SMITHSONIAN INSTITUTION 

FEBRUARY 28, 1929 



Zh £ovd Qg»afttmove (Preeo 

BALTIUOBX, MO., 0. S. A. 



PARASITES AND THE AID THEY GIVE IN PROBLEMS 

OF TAXONOMY, GEOGRAPHICAL DISTRIBUTION, 

AND PALEOGEOGRAPHY 

By MAYNARD M. METCALF 
The Johns Hopkins University 

A new method of approach to problems of wide interest is a most 
welcome thing if it gives assistance in reaching reliable conclusions. 
The concomitant study of parasites and their hosts is proving of im- 
portance in the revealing light it is throwing .upon questions of genetic 
relationships among organisms, upon problems* of their places and 
times of origin, of their routes of dispersal, and thus also upon prob- 
lems of former geographical conditions, including not only land con- 
nections for the dispersal of land animals and plants but also inter-sea 
connections for the wandering of marine organisms. Host-parasite 
data cast light also upon problems of former climates, whether warm 
or cold, wet or arid ; and they assist in questions of the whole character 
of the habitat of former animals and plants. The method is of such 
crucial import that it seems well to review briefly such use as has thus 
far been made of it, and especially to point out possible extensions 
in its use. 

In only a few instances have host-parasite data been used in con- 
nection with these broad taxonomic, geographic and paleogeographic 
problems, and an historical review of the use of the method can be 
brief. On the other hand, it is no simple task to illustrate adequately 
the method and to show at all fully the extent of its application, for 
it enters into and illuminates some very complex problems. In these 
complex problems host-parasite evidence must be interwoven with 
data from taxonomy, paleontology, geology, geography, biogeography 
and paleogeography. Like most classes of data of major significance it 
has wide interconnections. 

A single instance of the use of host-parasite data may well be given 
in introduction, to make the subject more concrete. Frogs of the 
genus Rana are wanting in South America and in Australia, except 
for R. palmipes along the northern coasts of the former continent 
and R. papua'' at the northern tip of Australia, both of these being 

* Harrison (1928) refers to four Anura, other than leptodactylids and 
hylids, as recent immigrants into North Queensland. I have not found first- 
hand reference to these forms. 

Smithsonian Miscellaneous Collections, Vol. 81. No. 8 



2 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

recent immigrants from the north. The place of the true frogs in 
these southern lands is taken by the Leptodactylidae, a dominant group 
which we might call the " southern frogs." This family is found in 
South xA.merica, Central America, the Antilles and along the southern 
coast of North America (many American genera and species) ; in 
Tasmania, Australia, Papua and adjacent islands, the Xew Hebrides 
Islands,^ and the Bismarck Archipelago (numerous Australasian 
genera and species) ; also in South Africa (one genus, three species). 
This remarkable distribution, in widely separated Southern Hemi- 
sphere lands, has caused much discussion. IMost zoogeographers have 
seen in this dispersal evidence of a southern land connection between 
Australia and South America. The discovery of southern frogs in 
Africa was so recent that the African occurrence has l)een but little 
discussed." Some students, though fewer recently than formerly, 
have vigorously disputed any such intercontinental connection, claim- 
ing either that the American southern frogs are not close relatives of 
those in Australasia (Gadow's earlier opinion, Eigenmann's later 
view), or that the southern frogs originally belonged in the whole 
Northern Hemisphere and that the South American and Australian 
representatives all came from the old common northern stock, and 
that more recently the northern members of the family have become 
extinct (^latthew 1915, Noble 1922, Dunn 1923). This seems a most 
unlikely suggestion in view of present knowledge. To be sure, the 
origin of the mammalia seems to have been in the northern land mass. 
The occurrence of mammals to-day in southern lands is due in con- 
siderable part to their having spread southward in the past, although 
some groups of major importance have evolved in the south, and one 
other, the marsupials, seem to have used east-west dispersal routes 
in both the Northern and the Southern Hemispheres. It is one of the 
leading mammalian paleontologists, Matthew, who has recently most 
^^gorouslv upheld this hypothesis of northern origin and southward 
dispersal and who has most extensively developed it. He has extended 
it even to the point of claiming the probable northern origin of all [ ?] 
groups of terrestrial animals [and plants ?] which arose during the 
Tertiary and probably also the Mesozoic periods, holding that the 
present Southern Hemisphere representatives of these groups are 
archaic forms crowded out from northern lands by the competition 

^ One report only, and this very doubtful, apparently erroneous. 

" I shall describe soon a Protoopaliua parasitic in the South African lep- 
todactylid Heleophryne, and discuss the significance of the presence of these 
forms in South Africa. 



NO. 8 PARASITES METCALF 3 

of more recently developed and more efficient relatives in the north/ 
He rejects all idea of east and west land connections in the Southern 
Hemisphere between the continents. 

Let us apply evidence from host-parasite data to the two concepts 
(i) of parallel evolution as explaining discontinuous distribution 
and (2) of onlv northern centers of origin and radiation for all 
Tertiary and Mesozoic forms, and let us in our illustration confine 
ourselves to the Leptodactylidae. and some of their parasites. 

In the recta of Australian and American southern frogs occurs a 
characteristic ciliate protozoan, Zellcriella, one of the Opalinidae, and 
some of these Australian and South American ciliates are almost if 
not quite specifically identical. This genus of ciliates is absent from 

^ Matthew postulates a northern source of origin for each group, which is 
like an ebullient spring with wave after wave overflowing, each successive 
wave pushing the previous wave outward in all directions in which conditions 
allow dispersal. Like the " age and area " hypothesis of Willis, this is too 
geometrical and too little biological. The recent tendency to attempt to express 
all biological conditions in geometrical figures and in formulae seems likely 
to prove but transient. To each of these hypotheses there is both theoretical 
and factual objection. It would indeed be strange if, as Matthew thinks, the 
animals [and plants?] dispersing in radiating streams should all leave behind 
them their ability themselves to become centers, springs, of further evolution 
on a large scale. There seems no theoretical ground of any" sort for this cor- 
ollary implied in Matthews' hypothesis. But, and this is more important, the 
facts do not seem to agree with Matthews' theory of one center of origin, with 
newer and newer forms continually appearing here and pushing the more archaic 
ones to the " ends of the earth." It seems rather to be the most vigorous, most 
dominant forms which spread to great distances, not the most ancient. It seems 
that these dominant animals and plants spread by their own vigor rather than 
that the less vigorous, archaic forms are pushed out to the far places of the 
earth by the vigorous competition of more dominant species. 

Note the conditions among the Anura. The genus Bufo arose probably in 
late Cretaceous times in northwestern South America or more probably in 
southeastern Asia (Metcalf, 1923, 1923a) and it has spread to all temperate 
and tropical lands except such as have been isolated and inaccessible (Austral- 
asia, Madagascar). The genus Hyla arose apparently in tropical South America 
in mid-Tertiary times and its spread to North America was after the middle 
Pliocene, when the Isthmus of Panama was formed; yet, in the comparatively 
short time since the mid-Pliocene one species of Hyla has spread throughout 
eastern and northeastern Asia, over Europe and on into northern Africa. The 
true frogs, Rana, probably the most modern of the Anura, have spread to all 
accessible portions of the world except that since they entered South Am.erica 
in the later Pliocene they have not spread beyond the Amazon river. No, it 
is not the more archaic forms but the more dominant forms that seem to be the 
wide wanderers. When a decadent group like the bell toads (Discoglossidae) 
has representatives in distant lands, it indicates, apparently, that once they were 
vigorous and have now become decadent (Metcalf 1928, 1928a). 



4 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

the Old World (excej)! Australasia) and in the New World is south- 
ern, having spread only as far north as the Gulf Coast of the United 
States (Metcalf 1923a). The parasites of the southern frogs indicate 
seemingly beyond question that the Australian and American southern 
frogs are related and also that they arose in the Southern Hemisphere 
and passed by some southern route from one to the other of their 
southern habitats. It might be possible, however unlikely, that the 
southern frogs of Australia evolved from very ancient ancestors ' in 
a way parallel to that of the South American southern frogs, though 
almost always in cases of parallel evolution there are found some 
criteria to distinguish such resemblance from that due to genetic 
relationship. But no one can for a moment believe that, along with 
the parallel evolution of the American and Australian hosts, there 
was also a parallel evolution of their opalinids, parallel to such a 
degree that almost or cjuite identical species of parasites are found 
in these frogs in South America and in Australia. The old hypoth- 
esis of parallel evolution, put forward by Gadow (1909) and others 
before the evidence from the parasites was known, could not now be 
seriously entertained and Gadow himself gave up the hypothesis. 

If then the southern frogs of Australia are close relatives of those 
of South America, how can we account for the present dispersal of 
this family? Nearly all zoogeographers, because of evidence from the 
Anura and from many other groups, both vertebrates and inverte- 
brates, believe in a former land connection between South America 
and Australia by way of an Antarctic continent, and a number of 
the more prominent students of the subject have emphasized also, in 
ih'is connection, the former existence of large connected areas of land 
in the Pacific, especially the Southern Pacific, Ocean. Phytogeog- 
raphers also have added much important evidence. The evidence 
from plants is, however, less convincing, since many seeds and spores 
may often be carried great distances by winds and by ocean currents. 

On the other hand a few students of dispersal have accepted 
(Noble 1922, 1925; Dunn 1923) or been favorably inclined toward 
(Schenck 1905, 1905a, 1907; Cheesman 1906, 1909) the hypothesis 
of origin in a northern land mass, Arctogea, and a southward dispersal 
via the Isthmus of Panama to South America, via Malaysia to Papua, 

^ Probably archaic toads, for archaic genera of Bufonidae are still found in 
Australia as well as in South America. Noble (1922, 1925) calls these forms 
leptodactylids. Archaic bufonids and archaic leptodactylids were probably 
very similar. Herpetologists in general class these ancient genera in Austi-alia, 
Africa and §.outh America as bufonids. From one of them in South America 
the leptodactylids apparently arose. 



NO. 8 PARASITES METCALF 5 

Australia and New Zealand, and also by way of the Isthmus of Suez 
to Africa. Here again the parasites of the southern frogs furnish 
evidence to be used in connection with other considerations. 

No southern frogs are known, either recent or fossil, from Euro- 
Asia, Malaysia or North America, except two species from the Texas 
coast. The opalinid ZcUcriclla is found in the southern frogs of 
South and Central America and in Tasmania and Australia and it 
probably will be found in Papuan representatives of this anuran 
family. If the southern frogs were ever in Arctogea with their 
ZellericUa parasites, both have completely disappeared. Why has not 
Zelleriella, at least, remained even if the frogs are gone? If Zclleriella 
ever was in southern frogs in Arctogea it should still be in some of 
the other Anura of these lands. Other families of Anura in South and 
Central America have adopted ZcUcriclla, for example the toads 
(Bufo), the tree frogs (Hylidae), the Dendrobatinae, the spade-foot 
toads, the Gastrophynidae, and even the ranids (PhyUobates, Pros- 
therapis, and one Calif ornian Rami). The absence of Zclleriella from 
Arctogea thus emphasizes the absence of the southern frogs as indi- 
cating that neither ever were at home in the North. 

There remains the j^ossible hypothesis that the southern frogs were 
once in the North but that their parasitic Zelleriellas did not evolve 
until their hosts had spread to the Southern Hemisphere. But this 
wholly gratuitous hypothesis does not help us, for we would still have 
to account for the discontinuous southern dispersal of the Zcllcncllae 
as due either to parallel evolution in South America and in Aus- 
tralasia, a wholly improbable conception, or to a southern land 
connection between these two now separated regions. The hypothesis 
of northern origin and southward dispersal of the southern frogs 
becomes grotesque in view of the evidence furnished by Zclleriella, 
and we shall see later that the evidence from the southern frogs and 
Zelleriella is reinforced by that from the southern crayfishes and their 
imrasites as well as by much other evidence. 

In our illustration we have seen host-parasite data used to indicate : 
(i) Genetic relationship between hosts; (2) places of origin and 
routes of dispersal of both hosts and parasites; (3) ancient land 
connections between now distinct and widely separated land masses. 

Taken in connection with generally accepted paleogeographical con- 
ceptions, similar host-parasite data can be used to indicate times as 
well as places of origin of host groups and parasite groups. For 
example both the southern frogs and their Zelleriella parasites are 
far more abundant and are more diversified in America than in 



6 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

Australasia. Origin in America seems indicated. If so, their spread 
to Australia must have been before the toads (Bitfo) with their very 
different opalinid parasites {Ccpcdca)^ had reached the South Ameri- 
can home of southern frogs. There is much evidence of the presence 
of an effective barrier, perhaps a shallow sea, across what is now the 
region in South America south of the East Brazilian highlands, sepa- 
rating them from Argentina, Chile and Patagonia. If the southern 
frogs and ZellericUa arose in the southern part of South America 
and if Biifo and its Cepedea parasites were of northern origin, as 
seems on many indications to be true, the origin of the southern frogs 
and ZcllerieUa and also the time of their spread to Australia must 
have been before the obliteration of this South Brazilian barrier 
(sea?) stretching from the Atlantic to the Pacific Ocean, or else 
Bufo, carrying Cepedea would have spread with the southern frogs 
to Australia. But this it did not do, for Bufo and Cepedea are un- 
known from Australasia. Patagonia united with Brazil during the 
middle Tertiary, perhaps about the middle of the Miocene period. The 
southern frogs and ZcUcricUa apparently evolved before that time in 
southern vSouth America or i\ntarctica and had reached Australia 
before Australia separated from Antarctica. 

In a similar way the present occurrence of the Hylidae (tree- 
frogs), interpreted in the light of their parasites, indicates a southern 
origin and a southern dispersal. But we are interested, at this point 
of our discussion, merely in illustrating the value and method of using 
data from both hosts and parasites together and not in establishing 
particular hypotheses, so we will not here enter on a discussion of 
the further evidence from the Hylidae. 

Having in mind this illustration of the host-parasite method, let 
us review briefly the use thus far made of the method and a few of the 
conclusions and hypotheses as to which it has given evidence. Then 
we will briefly consider possible extensions of the use of the method to 
other groups of hosts and parasites. 

Only a few students have used host-parasite data for evidence as 
to genetic relationships of hosts, their origin and their migration 
routes, or as to paleogeographic prol)lems, or as to all three. 

^ Opalina does not occur in South America in toads or in any other hosts, 
though a number of species of Bufo in Central and North America carry 
Opalina. The toads of South America probably came from Asia in the Creta- 
ceous, before the genus Opalina had evolved, and came by a route that did not 
include the continent of North America as at present formed. Opalina probably 
evolved in soutlieastern Asia in the earl}^ Tertiary (c/. Metcalf 1923). 



NO. 8 PARASITES METCALF • 7 

V^on Ihering, in 1891, in discussing ancient land connection between 
southern South America and Australasia, points out that once Pata- 
gonia and Chile, on the south, were separated by sea from the Ecua- 
dorean highlands and from the ancient plateau in eastern Brazil. 
Adducing evidence that southern Brazil was then united to Chile and 
Patagonia rather than to the Brazilian highlands, he writes : "Aeglca 
lacvis [a freshwater decopod crustacean] occurs in Rio Grande do 
Sul [southern Brazil] and in Chile and in hotJi places zvith the parasite 
Tcmnocephala chilensis'' [an ectoparasitic flatworm].^ This, so far as 
I can learn, is the earliest instance of using evidence from parasites to 
reinforce evidence from their hosts in discussion of problems of 
dispersal. 

In 1902 von Ihering made extensive use of parasite data in deter- 
mining the place of origin of different South American vertebrates, 
especially mammals, discussing whether they evolved in South Amer- 
ica or arose north of the Isthmus of Panama and spread to the 
southern continent. The data he used were from parasitic worms : 
Acanthocephala, Trematoda (flukes), Cestoda (tapeworms) and Ne- 
matoda (pinworms, etc.). In his discussion he makes the following- 
points : 

Two species of hosts are of common descent if they are parasitized 
by the same species or by nearly related species of parasites. 

North America and South America were not united as now until 
Pliocene times. 

There are two classes of elements in the neotropical fauna, one 
class autochthonous, a second class heterotochthonous, having been 
derived from North America and having entered South America since 
the beginning of the Pliocene period. 

The long isolation of the autochthonous South American mammals 
during the Tertiary period should have developed in them species of 
worms different from those in the heterotochthonous mammals, the 
parasites of the latter showing resemblance to those of holarctic 
mammals. 

The facts exactly agree with these theoretical considerations. Only 
the autochthonous South American hosts carry peculiar species of 

^ Italics mine. 

^ I have distinct memory of reading years ago mention by von Ihering of 
the genetic divergence between the freshwater mussels of southern and northern 
South America and his saying that those of the Argentine and of southern- 
most Brazil are like those of Southern Chile west of the Andes, and that they 
have the same parasites, but search of those of von Ihering's papers now ac- 
cessible to me has failed to yield this reference. 



8 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

Acanthocephala, while the heterotochthonous hosts carry both pecuHar 
species and species common to both northern hosts and southern hosts. 
He carries the study further to inchide host-parasite conditions among 
mammals, birds, reptiles, amphibia, and freshwater fish. In conclusion 
he says, '* The worms prove a valuable aid in analytical study of 
zoogeography and paleogeography." 

There could hardly be a clearer example of the use of parasite data 
in study of these broad problems. It seems natural therefore to use 
the phrase " the von Ihering method " of utilizing host-parasite data. 

Five years later than von Ihering's earlier paper, but six years 
earlier than the paper last cited, Vernon Kellogg (1896) discussed 
the biting lice of birds as giving evidence of genetic relationships 
between their hosts. In a later paper (1913) he notes the following 
instances of species of these mallophagan parasites being common to 
American and European birds not of the same species : The American 
and the European avocets do not meet, yet they have two mallophagan 
species in common ; American and European coots similarly do not 
meet, yet have five mallophagan species in common ; American and 
European bitterns are infected by the same mallophagan parasite. 
Other examples are American and Old World water-ousels ; one 
American and one Old World kinglet ; one mallophagan species 
common to two Old World and two New World crows. He writes 
(1896, p. 51): 

The occurrence of a parasitic species common to European and American 
birds, which is not an infrequent matter, must have another explanation than 
any yet suggested. This explanation I believe is, for many of the instances, 
that the parasitic species has persisted unchanged from the common ancestor 
of the two or more now distinct but closely allied bird-species. 

Kellogg repeatedly emphasized this idea of the interpretative value 
in bird-taxonomy of evidence from their parasites. In 1902, in a 
report by himself and Kuwana upon the Mallophaga of Galapagos 
Islands birds we find the paragraph : 

It was hoped that the character of the parasites found on the strictly Gala- 
pagos Island bird hosts might throw some light on the relationships of these 
birds to continental genera and species, but our knowledge of the distribution 
of the Mallophaga is yet far too meager to give much value to suggestions and 
especially as we have no data at all regarding the Mallophaga of birds from 
the west coast of South America 

The authors, however, found that of the 44 mallophagan species 

collected on the expedition 19 were identical with those Kellogg 

had previously studied from North American and Central Ameri- 
can birds. 



NO. 8 PARASITES— METCALF 9 

In 1905 Kellogg writes : 

From this fact of near relationship of hosts in all the cases of parasite species 
common to several host-species it seems almost certain that this common oc- 
currence, under circumstances not admitting of migration of the parasites from 
host to host, is due to the persistence of the parasite species unchanged from 
the time of the common ancestor of the two or more now distinct but closely 
allied bird-species. In ancient times geographical races arose within the limits 
of the ancestral host-species ; these races or varieties have now come to be 
distinct species, distinguished by superficial differences in color and markings 
of plumage, etc. But the parasites of the ancient hosts have remained unchanged ; 
the plumage as food, the temperature of the body, practically the whole envi- 
ronment of the insect, have remained the same ; there has been no external factor 
at work tending to modify the parasite species, and it exists to-day in its ancient 
form, common to the newly arisen descendants of the ancient host. 

Again in 191 3 and in 1914 Kellogg cited the same data, and also 
other similar conditions for the Mallophaga and Anopleura (sucking 
lice) of mammals and urged further collection and compilation of host- 
parasite data for these hosts and parasites. 

Kellogg writes (1913) : 

From the three Acarinate or Ratitian bird orders the Rheiformes, or South 
American rheas, the Casuariiformes or Australian cassowaries, and the Struthi- 
oniformes or African ostriches, only five species of Mallophaga have so far been 
recorded. On the rheas occur three species of Lipcurus, one being found on each 
of two host species and the other two on a third. On one species of AustraHan 
cassowary are found two Mallophagan kinds, one of which is the same species 
as that found on two of the South American rheas, while from the African 
ostrich, Struthia caiuclus, are recorded two parasite species, one of which is 
the same as that found on the third rhea. 

It is clear that Kellogg, like von Ihering, saw the value of evidence 
from parasites as to genetic relationships between hosts, and as to 
recent and ancient dispersal of the hosts. The importance of such 
evidence in paleogeographical studies was not mentioned by Kellogg, 
but was implicit if not expressed. Since he makes no reference to 
von Ihering's studies, Kellogg seems to have reached independently a 
realization of the important aid parasites give in the study of genetic 
relationships and of zoogeography. 

In 1909 Williams published a paper on the great epidemic among the 
Indians of New England in the years 1616-1620. The following 
quotation shows that he had a view of the bearing of parasitic disease 
upon questions of the origin and dispersal of human races and he 
paralleled Kellogg's conception of commimity of parasites among birds 
indicating common ancestors : 

From this point of view [of geographical origin and distribution] it is of 
interest to study the relation of the American race to infectious diseases. Any 



10 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

communicable disease occurring at the time of the discovery of America on 
either the eastern or the western continent exclusively probably originated on 
that continent. Any communicable disease belonging at that date equally to 
both halves of the world may probably be referred to a time at least as remote 
as that when the American race separated from the rest of mankind. 

At least two other students came independently to the same realiza- 
tion of the importance of host-parasite data, Launcelot Harrison 
being the next. In 1911 he discussed genetic relationships of hosts 
on the basis of their parasites, and strangely enough it was the birds 
and their Mallophaga which first brought to him, as to Kellogg, this 
conception of the use of parasite data. I have not had access to the 
original record of this first discussion by Harrison, but he later refers 
to it as follows : 

My personal connection with this subject dates from 191 1, when, after about 
a year's study of Alallophaga, I read a paper before the Sydney University 
Science Society upon the possible value of these parasites in determining bird 
affinities. The manuscript of this paper has been lost, but an abstract was 
published in the annual report of the Society for 1911-12, which I quote to show 
that I had already arrived at some definite conclusions in advance of/ and 
independently of, Kellogg : 

Wednesday, i6th August (1911). — Held in the Geology Theatre, the Presi- 
dent in the chair. L. Harrison read a paper, illustrated with lantern-slides, on 
"The Taxonomic Value of Certain Parasites". The parasites referred to are 
the biting lice (Mallophaga) found upon birds or mammals. Owing to both 
environment and food remaining unchanged through the centuries, these insects 
have not differentiated as fast as their hosts, and aft'ord indications of original 
relationship between birds that have diverged widely from parent stock. Though 
birds can be divided into good natural groups, the relationships between these 
groups have not, and cannot, be satisfactorily determined on anatomy alone. 
So any line of investigation that is likely to aid the solution of bird phylogeny 
deserves consideration. Some evidence is afforded confirming parts of existing 
classifications. Among other results, a study of the Mallophaga would suggest 
the inclusion of the penguins with the fowls, pigeons, and tinamous, a relation- 
ship that has never before been suggested. Such results could, of course, only 
be put forward as suggestions to the morphologist. A preliminary examination, 
however, of this group of parasites, certainly suggests that more complete 
knowledge will afford valuable clues towards the solution of bird taxonomy. 

Between 1914 and 1922 Harrison published seven more papers 
discussing Mallophaga of birds and bird relationships. In 1924, he 
discussed at some length the former connections of Antarctica with 
other southern lands, quoted my own work on evidence from the 
Anura and their opalinid parasites and came to its support with bio- 
geographic evidence and also with further host-parasite data from 

^ Kellogg antedated Harrison in this use of parasite data to determine bird 
relationships, but the realization of the importance of such data came to Plarrison 
independently. Later he saw that much wider groups of problems are approach- 
able through the host-parasite method, and his papers since 1924 discuss some 
paleogeographical questions connected with Australia, using host-parasite data. 



NO. 



PARASITES METCALF 1 1 



flukes (Trematoda) and tapeworms (Cestoda) of mammals, birds and 
frogs (quoted from S. J. Johnston 1913, 1914, 1916), from biting 
lice (Mallophaga) of Australian and South American mammals, from 
fresh water Crustacea and their worm parasites (Temnocephala). ^ 

Biting lice belonging to three dififerent groups, and which Harrison 
suggested (1922) might well constitute a distinct family, occur upon 
Australian and South American marsupials and South American 
porcupines/ Harrison says : 

There is no evidence that these parasites have ever existed on other mammals 
in more northerly lands, and it seems most probable that they would have left 
residuals here and there if such had been the case. So here again the greater 
probability lies with Antarctic connection between South America and Austraha. 

As to the freshwater crayfishes and their geographical distribution 
(Australia, New Zealand, Madagascar, South America, with one 
"northward wanderer" in Cahfornia), Harrison writes: 

This is a case in which parasites can be used to aid us. The four southern 
groups of crayfishes^ all carry ectoparasitic temnocephaloids, a group generally 
associated with the monogenetic trematodes [flukes], though differing from these 
in certain important features. They are confined to fresh water, and are para- 
sitic on the following hosts other than crayfish: tortoises (Brazd), shrimps 
(Argentina), molluscs (Brazil), crab (Matto Grosso) ; shrimps and an isopod 
(Australia); Crustacea (Java to Philippines). In addition, one species has 
apparently succeeded in reaching the northern crayfishes at their southern limit, 
Tcnmoccphala mexicana being recorded from Cambarus digniti of Mexico. 

From the greater variety of hosts upon which they are found in South 
America it would seem that the Temnocephaloidea were evolved there, becoming 
parasitic upon the ancestors of Parastacus, and were carried with the migrating 
Crustacea to Antarctica, New Zealand, Australia, and Madagascar (perhaps by 
way of the Molluccas and Seychelles, as has been suggested for many other 

animals). , , , , 1 1 -^ 

If crayfish had ever existed in Africa, they must have had temnocephaloid 
parasites, since the Malagasy genus Astacoidcs has them, if it be presumed 
that the latter were derived from the former. It would follow that the Holarctic 
crayfish must have had these parasites. If so, where are they now? It is 
too much to ask us to believe that they have become extinct m the northern 
temperate zone when we find them so widely spread and holding their own in the 
southern. There is no evidence that crayfish have ever existed m the tropical 
belt and the fact that their place is filled there by other creatures, such as fresh- 
water crabs, and giant prawns, seems to indicate positively their non-existence 
at any time. 

In 1926 Harrison again discusses Antarctica as a center of radiation 
for plants and animals, using host-parasite data as " crucial evidence." 

^The porcupines are a peculiar group whose relationships to other rodents 
are not understood. It would be especially interesting to know what, if any, 
Mallophaga are found on African porcupines. 

^ Geographical, not taxonomic, groups, in the four lands named above. 



12 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

One quotation, showing his effective use of hosts and parasites to- 
gether as sources of evidence, may well be given here. After dis- 
cussing again the Crayfish and their external parasites, the temno- 
cephaloids, he writes : 

The acceptance of Matthew's hypothesis of four separate dispersal streams of 
crayfishes from the northern hemispliere potamobiids [northern crayfish] into 
Madagascar (through Africa), Australasia, New Zealand and South America 
implies : 

The presence in the past of temnocephaloids upon northern potamobiids, for 
which there is no evidence. 

The extinction of both crayfishes and temnocephaloids in Africa, where there 
is no evidence that either ever existed and no obvious or plausible reason .... 
why either or both should have become extinct. 

The general distribution in the past of both crayfish and their parasites in 
the tropical belt, for which again there is not positive evidence. Moreover, since 
opportunity has been afforded for the southern crayfish to migrate into the 
tropical belt, and since they have not done so to any marked degree, it would 
seem that the tropics do not afford a congenial environment for crayfishes. 

The extinction of temnocephaloids upon Asiatic and North American potamo- 
biids, for which there is no evidence, and which should not, I think, be assumed 
without some justification or explanation. 

These considerations seem to me to rule out Matthew's hypothesis completely. 
If the parastacids [southern crayfish] have been derived from potamobiids, the 
only possibility seems to be that such derivation took place in America, and that 
the parastacids, as such, first appeared in South America, and must have reached 
the other southern land masses by a southern route of dispersal, carrying their 
temnocephaloid parasites with them. 

In 1928 two more papers liy Harrison appeared. One (1928) 
presents important additional evidence as to antarctic zoogeography. 
A genus of lowly segmented worms, Stratiodrilus (one of the 
Histriobdellidae) occurs on fresh water crayfish in Tasmania, in New 
South Wales, and in Uruguay, and in this paper Harrison describes a 
fourth species on a crayfish from Madagascar. He discusses the family 
Histriobdellidae and its three genera and he prophesies that one or 
more species of the southern genus Sfrafiodrilus will be discovered 
on the gills of other South American crayfish (Parastaciis) and of 
New Zealand crayfish (ParaiicpJiros). 

The second of Harrison's papers in this year (1928) is an excellent 
general review of the whole host-parasite method. He had not learned 
of von Ihering's thorough-going use of this method of illuminating 
problems of genetic relationships of hosts, of geographical distribution 
of both hosts and parasites, and of former intercontinental connec- 
tions. Also he failed to realize the extent of Kellogg's appreciation 
of the wide applicability of the host-parasite method. Harrison's own 
realization of the broad value of such data apparently came from 
reading two of my papers and from correspondence with me in the 
year 1921, a correspondence which, though brief, was very valuable 



NO. 8 PARASITES — METCALF I3 

to me. But his grasp of the importance of parasites as indicating 
relationships of hosts was reached independently of von Ihering and 
Kellogg and much antedated my own. The following quotation shows 
Harrison's grasp of the wide extent of the usefulness of the host- 
parasite method : 

The ostriches of Africa and the rheas or nandus of South America are 
commonly supposed by ornithologists to have arisen from quite distinct stocks. 
But their lice are so similar, and so different from all other bird-lice, that these 
must have evolved from a common ancestor, and so also must the birds them- 
selves. Evidence derived from lice is confirmed by the cestode and nematode 
parasites of the two groups of birds. Thus a phylogenetic relationship may be 
established by means of parasites. Equally, a supposed relationship may be 
refuted. Their lice prove that the penguins are in no way related to any northern 
group of aquatic birds, but belong in an ancient complex which includes the 
tinamous, fowls and pigeons ; that the kiwis of New Zealand are modified rails, 
and not struthious birds at all ; that the tropic-birds are not steganopodes but 
terns, and so on. A third use is to refute suggestions of convergent resemblance, 
which are often very lightly made, and which are so exasperating to the zoo- 
geographer since they are usually incapable of either proof or disproof. Lepto- 
dactylid frogs are found in South America and Australia. Did they evolve 
separately, or are they derived from common ancestors? The herpetologist 
cannot say with any certainty, but the parasitologist discovers that they share 
a genus, Zelleriella, of ciliate protozoan parasites, and must have had common 
origin. This same example will serve to illustrate a fourth use for the host- 
parasite relation. The genus Zelleriella can, and does, infest frogs other than 
Leptodactylids. It is not found, however, anywhere except in Australia, South 
and Central America, so that its distribution affords strong presumptive 
evidence that South America and Australia have been joined in past time in 
some way which excluded the northern land masses. 

These examples indicate the nature of the host-parasite relation, and its 
possible usefulness. 

In 1926 Harrison discussed before the Australian Association for 
the Advancement of Science " The Composition and Origins of the 
Australian Fauna, with Special Reference to the Wegener Hypoth- 
esis." This paper, in press hut still unpublished in 1928, I have, of 
course, not seen. 

S. J. Johnston, of Sydney, Australia, had heard Harrison present 
before the Sydney University Science Society his first discussion of 
the biting lice ( Alallophaga) of birds as furnishing evidence of the 
genetic relationships of their hosts (Harrison 191 1) and two years 
later Johnston (1913) wrote of the frog trematodes of Europe, Amer- 
ica, Australia and Asia and their bearing upon possible former con- 
nections between these now separate lands. He concluded that the 
trematodes of Australian frogs find their nearest relatives in those of 
Asiatic frogs, and Grobbelaar, writing in 1922 upon African frogs 



14 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

and their trematodes, accepted this judgment of Johnston's. Harrison 
questions this conclusion and predicts *' with the utmost confidence " 
that future additions to the then very scant knowledge of Asiatic frog 
trematodes (six species) and the Trematoda of Australian frogs will 
show " that .... the closest affinities of Australian frog trematodes 
.... lie with those of South American frogs." In this 191 3 paper 
Johnston refers to trematodes of AustraHan sea eagles, sea gulls and 
herons and he points out also that two flukes of the genus Harmosto- 
mimi found in two Australian marsupials are so closely related to 
another Harinostoinuiii from a South American opossum that they 
" must be considered as derived from common ancestors." Johnston 
must have had in mind the bearing of these parasite data upon prob- 
lems of former connection of Australia with Asia and with South 
America, but neither in this nor in two subsequent papers ( 1914. 
1 916) upon Australian trematodes and cestodes in general did he 
bring out clearly the paleogeographic importance of his data. He 
emphasized chiefly their bearing upon the genetic relationships between 
the hosts. 

Metcalf, the author of the present paper, was the fourth student 
of parasites to come independently to a 'realization of the important 
aid which parasites may give in solving proljlems outside the field 
of parasitology proper, and he used the host-parasite method in his 
earlier papers ' much more extensively than it had been used before ; 
but really he added nothing essential to the conception of this method 
which von Ihering had in 1891 and 1902. Kellogg too seems to have 
realized the applicability of the host-parasite method to other problems 
than genetic relationships of hosts, though he made but scant, if any, 
application of it to them. Harrison carried Kellogg's work upon bird 
relationships further and also in his papers subsequent to 1924 used 
parasite data extensively in problems of zoogeography and paleogeog- 
raph}'. Priority is of very little interest, but, for what it is worth in 
this matter, the priority is clearly von Ihering's. 

Metcalf in his chief paper (1923) purposely overemphasized his 
data, endeavoring to bring out even slight suggestions which could not 
be established without corroboration from other sources.^ His desire 

^ Seven papers from 1920 to 1924; also one in 1928. 

^ " The endeavor will rather be to present the known data from the Anura and 
the Opalinidae and note their implications. Even very scant data, insufficient to 
have any real weight as they stand, will be stated and their implications noted, 
with the thought tliat even very minor items, of slight moment by themselves, 
may sometime be correlated with other data and then be of interest. The 
endeavor is, therefore, to have the treatment of this theme inclusive rather than 
critical." (From Metcalf, 1923.) 



NO. 8 PARASITES — METCALF 1$ 

was not so much to prove certain particular taxonomic, zoogeographi- 
cal and paleogeographical propositions as to illustrate and emphasize 
the method of using parasite data in the study of such problems. 
That, indeed, is the chief purpose of the present paper also. 

Metcalf studied the opalinid parasites found in the preserved Anura 
(frogs and toads) in the United States National Museum, including 
species from all parts of the world. He was already familiar with 
those occurring in Europe. Other species were obtained from the 
Indian Museum at Calcutta and a few more from South America. 
Assuming the general correctness of a set of Mesozoic and Tertiary 
maps compiled by himself, chiefly from Arldt, von Ihering, Scharfif 
and Schuchert, and based upon geological and biogeographical evi- 
dence, not including parasites, he studied conjointly the taxonomy 
and distribution of the xA^nura and their opalinid parasites and applied 
these data from biogeography, paleogeography and from the host- 
parasite studies, to problems of the place and time of origin of differ- 
ent hosts and groups of hosts, of different parasites and groups of 
parasites, to the routes, times and directions of dispersal of both hosts 
and parasites, and in the discussion pointed out evidence bearing on the 
correctness of the maps used, and upon problems of ancient climates. 

Before applying the data from the study of the opalinid parasites 
he tabulated the available data from both hosts and parasites under 
six items as follows : " Species of opalinid ; Host species ; Family 
or subfamily of host ; Known geographical occurrence of opalinid 
in the species of host named ; Known occurrence of host ; Known 
occurrence of genus of host." This tabulation, used in connection 
with maps of the present day oceans and of the continents in the 
several geologic periods, was of great aid in studying present and 
former distribution of both hosts and parasites, places and times of 
origin of each and routes and directions of dispersal. The publication 
of similar tables may properly be urged upon those zvho undertake 
comprehcnsiz'e studies of any group of parasites. They will make 
the author's data most easily available to other students and so should 
extend the general use of host-parasite data. Where data from fossils 
of either hosts or parasites are known and are sufficiently extensive 
they should be tabulated, say under such items as these : Geographic 
locality of fossils of the host family ; Geologic period of such fossils ; 
and, if fossil remains of the parasites are known, similar data as to 
them should be tabulated. Of course preservation of parasites as 
fossils will be rare, but their spoor may be found and may be quite 
specific, as, for example, in the case of the Peridermiums of pines. 



l6 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

rusts which produce swelHngs of possibly specific character. Other 
examples would be bone lesions of recognizable cause. 

Let me here merely list a few of the things that seemed to be 
indicated with a greater or less degree of probability by these earlier 
studies of Metcalf. 

Having assumed paleogeograjjhical maps showing certain intercon- 
tinental connections, he applied to them the data from Anura and 
their opalinid parasites and found they fitted in such a way as to be 
in general confirmatory. 

Protoopaliua, the most ancient genus (jf the opalinids, was present 
in Equatoria (Australia plus Africa and South America) as early as 
the Triassic period, and its most archaic subgeneric group of species 
have persisted in these three continents, with only slight modification, 
until the present day. 

Other subgeneric groups of species of Protoopalina arose as follows : 

Group II in Australia at a time not indicated by the data. 

Group III before the separation of Australia from Asia in Jurassic 
or early Cretaceous times, in Australia or southeastern Asia, spreading 
to Europe during the Cretaceous or early Tertiary by a route north 
of the Himalayas, and to Africa in the late Tertiary, entering from 
the northeast. 

Group IV, in the Jurassic period, in Australia or southeastern Asia. 

Group V, in Cretaceous times in Australasia, their presence in 
Australia and Java but not in Sumatra indicating that Java retained 
connection with Australia longer than did Sumatra. The absence of 
members of this group from South America is one of several bits 
of evidence indicating that migration between South America and 
Australia was chiefly westward. 

Group VI, in the Jurassic period in Australia. 

Group \ II, in Precretaceous or Cretaceous times ^ in South Atlantis 
which united Patagonia to South Africa. 

Group VIII, during the Tertiary period in western North America. 

Group IX, in Jurassic times in Lemuria (the Indian Ocean land 
connecting Madagascar and India, see fig. 3), with a Tertiary dis- 
persal to eastern Asia, Formosa and Java. 

The opalinids of the earliest Anura were apparently of the genus 
Protoopalina, as evidenced by structure, life history and distribution, 
since Protoopalinac occur in all families of Anura whose habits permit 
infection with opalinids. 

^ Later studies tend to place this South Africa-Patagonia union somewhat 
later, in the early Tertiary. 



NO. 8 PARASITES METCALF I? 

The genus ZcUcridla arose in Patagonia, before the separation of 
Patagonia from Antarctica. This separation occurred probably in the 
middle Miocene. ZcUcridla did not arise until Patagonia had lost its 
African connection, for the genus does not occur in Africa. In the 
early or middle Tertiary it spread to Australia ; in the late Tertiary 
to Tropical America. Its original hosts were southern frogs (lepto- 
dactylids). Its presence in South America and Australia, and its 
absence from Euro-Asia is, when carefully studied, as already noted, 
evidence of former southern land connection between these continents. 
To continue merely listing the things indicated by Metcalf's host- 
parasite data from Anura and their opalinids would be wearisome, so 
we will omit reference to the genera Ccpcdca and Opalina and their 
subgenera, whose times and places of origin and times and routes of 
dispersal were discussed, and will note further only some of the types 
of conclusions suggested. 

Evidence was found as to the places and times of origin of the 
several families of frogs and toads, and the routes by which, and 
the times at which, they spread to the lands they now occupy. There 
are similar indications as to a number of genera of the hosts, Bufo, 
Polypcdatcs and Rana, for example. 

Spread of true frogs {Raninac) from the north into South America 
has not occurred, except for one species, and there are no indications 
of any southward wandering of Anura across the Isthmus of Panama 
since its formation in the Middle Pliocene. On the other hand, there 
has been extensive spread of Anura northward across this Isthmus. 

The Sonoran desert of northern Mexico and the southwestern 
United States has been a hindrance to northward wandering of 
southern frogs since the middle Pliocene, but has not held back the 
tree frogs (Hylidae). 

Negative as well as positive evidence is often given. For example, 
the absence of Zelleriella — the characteristic opalinid of the southern 
frogs— from Euro-Asia indicates that southern frogs were never 
in Euro-Asia. The alisence of the genus Opalina from South America, 
though it is present in the toads (Bufo) in Central America, shows 
that toads have not passed south across the Isthmus of Panama since 
Opalina, a Tertiary immigrant from Asia, reached Central America. 
Again the only Euro- Asian species of tree frog (Hyla arborea) with 
its several subspecies is not endemic in Euro-Asia, but is an immigrant 
from North America, for it carries a North American Opalina. 

This recital of a few of the indications from Metcalf's studies is 
sufficient to emphasize the point here in view, namely, that host- 



l8 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

parasite data may be applied to a great range of problems. This, 
which we might well name the von Ihcring method, gives decisive 
results in many cases, while in other instances it furnishes merely 
corroborative evidence or evidence to be joined with that from other 
sources. 

Metcalf subsequently published several papers discussing the host- 
parasite method or host-parasite data, as noted in the appended 
bibliography. 

Darling (1921, 1925) used data from the hookworms of man to 
indicate human origins and migrations. Before the publication of this 
earlier paper Darling had very likely not read the papers of von 
Ihering, Kellogg, Harrison, Johnston and Metcalf, which had made 
somewhat similar use of parasite data, for he does not refer to these 
authors. It seems probable, therefore, that Darling may have been 
another independent discoverer of the broad significance of such data 
from parasites. The following quotation will show Darling's sug- 
gestions : 

.... man of the Holartic regions [is] parasitized exclusively or almost ex- 
clusively by Ancylostoina duodenalc, while man of the Oriental and Ethiopian 
regions [is] parasitized exclusively or almost exclusively by Nccator americanus. 
This .... suggests the possibility of ... . there having been two primitive 
races of man, each one originally parasitized by a particular species of worm. 
Certain it is that N. americanus is found more exclusively among' black and 
brown-skinned races, while A. duodouilc is found exclusively or greatly pre- 
dominates at the present time among Caucasian and Mongoloid stocks. 

It may be that a Eurasiatic race of men, possibly the Pithecanthropus of 
Trinil, Java, became split off and furnished the stock from which man of oriental 
and Ethiopian regions sprung. Proliopithecus emerging from Holarctic Africa 
may have been not only the parent form of man, gibbon, chimpanzee, gorilla 
and the orang-outang, but he may have harbored the parent form from which 
have arisen the different hookworm species found in the various species of 
anthropoids of today. Possibly the ancestral tree of the primates can be revised 
after a study of the host relationships of their respective obligate nematode 
parasites. At any rate we can say that it seems likely from the present distribu- 
tion of A. duodenalc and A'^. americanus as determined in surveys recently made 
of selected groups that there were originally races of man parasitized exclusively 
by A. duodenalc and inhabiting the Holarctic region, that is Europe, Asia, north 
of the Oriental region, and northern Africa ; and that there were other races 
of man parasitized exclusively by N. americanus and inhabiting the Oriental 
region, that is the southern peninsulas of Asia and Indoasia or the Malay Archi- 
pelago ; and also the Ethiopian region, that is, Africa south of the Sahara 
Desert. 

Ewing (1924) in a study of biting lice of the family Gyropidae 
discusses the significance of their geographical and host distribution 
arguing in favor of a crossing over between rodent hosts and primate 



NO. 



PARASITES METCALF IQ 



and ungulate hosts rather than descent from common ancestors. In 
a second paper (1924a) Ewing discussed the host-parasite relations 
of human and louse races and the hybridization of both and he includes 
in this discussion prehistoric races of men and of their head lice, and 
he mentions again the probability that the tropical American spider 
monkeys {Ateies) acquired their head lice (Pediculus) "originally 
from man but not from recent man." Two years later the same author 
(Ewing, 1926) discusses further the significance of the geographical 
and host distribution of the genus Pcdiculus. Four paragraphs of his 
summary may well be quoted : 

1. In America two distinct groups of Pcdiculus exist, one of them confined 
to man and one to monkeys. 

2. The forms infesting man are apparently largely hybrid races of head lice, 
the pure strains of which were originally found on the white, black, red, and 
yellow races of man living in their original geographic range. 

6. The monkey-infecting pediculids of America, so far as known fall into 
distinct species according to the hosts they infest, thus indicating, to a certain 
degree at least, a parallel host and parasite phylogeny. 

7. If these monkey hosts (Ateies, species) procured their lice from man it 
was not from recent man but from human hosts that lived tens of thousands 
of years ago— long enough to allow a species differentiation to develop among 
the monkey hosts. 

Ward ( 1926) , in a presidential address before the American Society 
of Parasitologists, has mentioned the importance of such uses of data 
from parasites and refers in this connection to some of the work 
reviewed in the present paper, 

Hegner (1928) discusses the protozoan parasites of monkeys and 
man and concludes with the following statement : 

.... the protozoan parasites of monkeys and man belong for the most part 
to the same species or are so similar in their structure, life-cycle and host- 
parasite relations as to be practically indistinguishable. This situation is par- 
ticularly striking when the protozoa of monkeys are compared with those ol 
other animals associated with man. If the proposition that close relationships 
of parasites indicate a common ancestry of their hosts is valid, then the facts 
available regarding the protozoan parasites of monkeys and man furnish evidence 
of importance in favor of the hypothesis that monkeys and man are of common 
descent. 

This shows Hegner's recognition of the importance of host-parasite 
data in studies of phylogeny. 

Some few students have attempted to minimize the importance of 
parasite data in problems of biogeography (Noble, 1922, 1925 ; Dunn, 
1925). Harrison (1924, 1926) has sufficiently answered their criti- 
cisms. Noble's criticisms are based largely upon his new classification 
of the Anura, a classification not as yet accepted by herpetologists. 



20 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

The present writer thinks improbable Noble's idea that the southern 
frogs of Australia and those of South America evolved independently 
from the archaic toads, and developed along parallel lines. 

So far as I can learn, the papers mentioned cover the use thus 
far made of data from parasites in connection with the three classes 
of problems here considered. So little has been done in this field and 
so little has that little been known that each successive student has 
thought himself a discoverer and a pioneer. It has been probably a 
unique incident in biological and geographical science. There have 
been instances of double or triple discovery — mutation, for example — 
but sixfold independent discovery of a concept with wide significance 
and capable of important application in further research has probably 
not before occurred. 

We have described in outline the use that has been made of this 
" von Ihering method." It seems well before closing this paper to 
suggest possible further applications of the method, using other groups 
of parasites, and to mention some specific problems needing study 
by this method. Harrison (1928) has reviewed from this point of 
view different groups of animal parasites considering their availability 
for host-parasite studies. Let us include plants as well. 

Protozoa — There are, of course, many groups of Protozoa part or 
all of whose members are parasites or commensals, having at any rate 
an obligatory association with definite animals or plants. Among the 
Sarcodina are many parasitic Amoebae and a few Heliozoa are inter- 
nal parasites. I know of no use of data from these forms in studying 
such general problems as we have had in mind. Our knowledge of 
the taxonomy of these parasites, of their host-occurrence and of the 
geographical distribution of l)oth parasites and hosts is inadequate, 
but the material for such host-parasite studies in these groups seems 
to be availa1)le. There is a considerable degree of specificity in the 
host relations of the Endaniocbac and they are found in many groups 
of animals. 

Multitudes of the flagellates are parasitic and probably no other 
group presents more advantageous material for host-parasite studies. 
Some flagellates are parasitic in plants. Although knowledge of flagel- 
late parasites is extensive, it is ver^^ fragmentary, being almost nil 
for many regions of the earth and far from complete for most regions 
and for most hosts. In some groups we have enough records to begin 
tabulating the host occurrence and geographical occurrence and scru- 
tinizing the tables for what the}- may indicate. Probably the finest 
groups for host-parasite studies are the termites (white ants) and the 



NO. 8 PARASITES METCALF 21 

flagellates living in their intestines. Approximately fifteen hundred 
species of termites are known and from all tropical and many tem- 
perate parts of the world. They have a highly elaborate taxonomy 
with four families, subfamilies, genera, subgenera, species and sub- 
species, and the genetic relationships and the phylogeny seem capable 
of successful study. Forty-six genera comprised in 12 families of 
termite flagellates have been described from less than 40 species of 
termites, this being but a meager beginning of the taxonomic and 
phylogenetic study needed for this truly vast number of mostly unde- 
scribed species. It seems unlikely that any other organisms will lend 
themselves so favorably to host-parasite studies as will the termites 
and their flagellates. Every individual termite is richly infected. The 
wealth of species of these hosts and of their Protozoa is so great as 
to be somewhat awesome. "There are probably more flagellate 
Protozoa in the intestines of termites than in all other animals com- 
bined." ' It is a bold student who attacks these groups with the idea 
of employing them b\- the von Ihering method, but the one who does 
so should reap a rich reward. 

The termites are a peculiarly favorable group for such studies be- 
cause, in addition to their varied internal fauna of flagellate parasites, 
they harbor, either customarily or occasionally, representatives of 
every other group of parasitic Protozoa (Amoebae, Ciliates, Sporozoa) 
so that one studying them through their flagellates would often be 
able to check up results from some of their other parasites. 

The Chlamydozoa are but little understood. It seems not unlikely 
that when better known, especially if they prove to be associated with 
mozaic and other filtrable virus diseases, they may prove of much 

interest. 

The Sporozoa offer much fine material for host-parasite studies, 
all being parasitic. Most species of terrestrial and fresh water animals 
harbor representatives of one or more of the numerous groups of 
Sporozoa, and they infect also very many marine animals. Many 
Sporozoa, perhaps most of them, show a high degree of specificity m 
their selection of hosts, being confined each to one species of host or 
to one taxonomic group of hosts. This renders their evidence m 
some instances peculiarly convincing. _ _ 

Among ciliate Infusoria are numerous parasitic species. Balantidmm 
and Nyctothcrns, parasites of man and other mammals, should be 
valuable for host-parasite studies. The "Astomata," which include 
several perhaps unrelated families, should also furnish favorable ma- 

' Cleveland, L. R.. quoted from a letter. 



22 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

terial. But best of all ciliates for such studies seem to be the archaic 
group, the prociliates.' including only the Opalinidae, the basis of 
Metcalf's studies, to which reference has already been made. 

The inability of their hosts, the frogs and toads, to endure salt 
water makes their evidence as to land routes of dispersal peculiarly 
cogent. Opalinids have remarkably clearly indicated phylogenetic 
relationships (Metcalf, 1926), probably more clearly indicated than 
in any other group of Protozoa. These two groups, the Anura and 
their opalinids, are thus peculiarly favorable for studies by the host- 
parasite method, especially studies of the phylogeny of the Anura and 
of their geographic dispersal. 

The Ophryoscolecidae, a group of ciliates which live in the stomachs 
or intestines of ungulates, anthropoid apes and some South American 
rodents, have a highly diversified taxonomy, with relationships well 
indicated, are almost world-wide in distribution and seem, from our 
present inadequate knowledge, to be specific as to their hosts. They 
and their hosts should furnish important host-parasite data. No 
animals are better represented in fossil records than are the Ungulata. 

Among the flatworms the Temnocephaloidea, with the crayfish on 
whose gills they are parasitic, have been used very effectively in host- 
parasite studies by von Ihering and Harrison, as already noted. Von 
Ihering and Johnston have made similar use of data from the flukes 
(trematodes), the tapeworms (cestodes), and some of their hosts. 
But the important results already obtained by aid of evidence from 
the flatworms are but a very minor fraction of the harvest that may 
be reaped by adequate study of this group. 

Darling's studies of the origin and spread of human races in the 
light of their hookworm parasites are an example of the use of data 
from round worms (Nematoda). Among the Nematoda there are 
innumerable free-living forms, and great numbers of parasitic species 
infesting almost all kinds of animals and very many kinds of plants. 
A parasitic nematode is even known from a ciliate infusorian — a 
metazoan parasite in a protozoon. There is in the parasitic members 
of this group and their hosts a wealth of material which should prove 
an inexhaustible mine for working by von Ihering's method. The 
nematodes rival the trichonymphs of the termites as a source of data 
for such use, indeed because of their universal abundance and the 
huge number of their species they must surpass the trichonymphs in 
the number and variety of problems their evidence will help solve. 

'Using Wenyon's (1926) modification of Aletcalf's name " protociliates ". 



» 



NO. 8 PARASITES METCALF ^3 

Harrison, as already described, has made use of parasite data from 
Stratiodrilu's, a genus of archaic annehds, to indicate intimate relation 
between Australasia, Madagascar and South America. The annehds 
as a class, however, are poor in parasitic species. 

Among the Crustacea the parasitic copepods may perhaps give light 
upon some interesting problems, though their host relations and 
especially the specificity of these relations need further study. The 
parasitic species of copepods are apparently chiefly ancient and 
reached for the most part their adaptation to parasitism long ago, 
having undergone little modification in later geologic periods. Others, 
however, seem to have adopted parasitism more recently. A thorough 
analysis of the parasitic copepods from this point of view would be 
worth while for its own sake and would give added significance to 
their host-distribution and geographical distribution. 

Among the Arachnoidea (spiders, mites, ticks, etc.) several groups 
are parasitic, but the parasites are not confined each to one individual 
host or even to one species of host. They are free to pass from one 
host to another. This makes them far less useful for host-parasite 
studies than are more restricted parasites, but, in some instances at 
least, they present usable data. 

The true insects include many groups among whose members 
parasitism is more or less well developed. Examples of insect parasites 
of terrestrial vertebrates and of insect parasites of insects at once 
come to mind, but with these insects, as with the mites and ticks, 
specificity of host-infection is in general not highly developed, though 
there are numerous exceptions in which there is constant relation 
between kind of host and kind of insect parasite, as, for example, 
some moths parasitic in bee colonies and some beetles restricted to 

ant nests. . . 

Many insects parasitic upon plants have closely specific host limita- 
tions being confined each to a single host species or to a related group 
of species, however freely they may pass from host individual to host 
individual. One thinks at once of the plant lice (Aphides), but many 
even of the larger insects have similarly restricted plant prey— ^. g., 
the potato beetle, the squash bug, the plum curculio, the hessian fly, the 
cotton boll weevil, grape Phylloxera, some butterflies, some moths, 
many gall-flies, etc. 

Molluscs, echinoderms, vertebrates and other chordates, show few 
examples of parasitism, commensalism or obligate association of any 
kind It is doubtful if the few cases known (shark-Remora, fish hving 
among the tentacles of jelly-fish, fish living within sea cucumbers, fish 



24 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 



living ill the mantle cavity of molluscs, and some others) will prove 
of much interest from the point of view of the present paper. 

Parasitic plants have never been used, so far as I can learn, in such 
studies as those in which we are here interested, though they present 
a great mass of usable host-parasite data, but in all the groups which 




Fig. I. — The Atlantic Ocean and the adjacent land areas. The dotted lines indi- 
cate 2000 fathoms depth. (Modified from a map by W. & A. K. Johnston.) 

furnish these data much further study is needed. A good degree of 
specificity lietween host and parasite is a desideratum and this we 
find in a good many cases. 

The rusts are very favorable in some regards. Most of them are 
restricted in their hosts, many cause lesions which can readily be 
recognized, as, for example, the Peridermiums of pines and the branch 
" nests " of cedars. Many of the rusts of the conifers produce distor- 
tions in the hosts which could be identified in fossils. The two hosts, 



NO. 



PARASITES M ETC ALF 



25 



intermediate and definitive, necessary for each species of rust, present 
a most interesting condition for distributional studies. The necessity 
for two hosts in the Hfe cycle of a rust, presents a complication, but 
one which makes the evidence from the rusts and their hosts more 
than doubly significant. On the other hand the rusts lack one ad- 




FiG 2— The Pacific Ocean and the adjacent land areas. The dotted lines indicate 
2000 fathoms depth. (Modified from a map by W. & A. K. Johnston.) 

vantage— their taxonomy is not well understood. This disadvantage is 
only partly compensated by their large number of forms and their 
numerous and diverse hosts. When the rusts are more widely and 
more thoroughly known they will present data of peculiar value in 
host-parasite studies. 

The smitts of grasses, especially of uncultivated grasses, might 
furnish data; so also the powdery mildews (Erisiphaceae) and the 
downy mildews (Peranosporaceae), especially those infesting unculti- 
vated species. 



26 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 



Mycorrhizae, commensal root fungi, of pines and many other groups 
might be of especial interest, first because the data they furnish might 
be compared with those from rusts and other fungi, and, second, 
because they produce lesions which possibly might be recognizable in 
fossils. 




Fig. 3. — The Indian Ocean and the adjacent land areas. The dotted lines indi- 
cate 2000 fathoms depth. (Modified from a map by W. & A. K. Johnston.) 



The fungi in general should be scrutinized for groups fitted for 
such studies. Fungus diseases of plants are being more and more 
studied and new data are thus being offered. 

Plants and their parasites, when studied by the von Ihering method, 
will surely give very important results, but such study must be accom- 
panied by further and laborious study of the structure, life history 
and taxonomy of the .parasites. 

Fossil records of the hosts are of especial interest in biogeographical 
problems and if these can be joined with fossil records of the parasites 



NO. 8 PARASITES — METCALF 2/ 

also it is still more fortunate. This cannot be expected in many cases, 
but there is prospect of some success in such study of bones of 
Vertebrata and their lesions (Moodie, 1923; Rupper, 1921), of 
conifers and their distortions caused by Peridermiums and My- 
corrhizae, of some other plants and their scars from fungus diseases, 
of many plants and their insect galls and probably of still other groups 
of animals and of plants showing fossil records of parasites. 

This paper may well close by suggesting as samples one or two 
special problems favorable for attack by the host-parasite method. We 
have already noted crucial data presented by parasites of several 
groups as to the problem of. east and west routes of dispersal in the 
Southern Hemisphere. The parasites of both plants and animals which 
show families, genera, and especially species, common to different 
southern lands, and southern lands only, may well be studied further. 
Such studies should finally determine not only the question of the 
former existence of such east and west migration routes, but also their 
position, their connections and their geologic time. On the other hand, 
if in some groups the dispersal was southward from northern lands, 
this fact will be demonstrated beyond dispute. Let us note here a 
partial list of species, genera, and families of southern occurrence 
whose parasites of all kinds should be studied (c/. figs, i, 2 and 3). 

Mammalia 

The marsupials of Australia and of America (mostly tropical America). 
Their biting lice (Mallophaga) have been somewhat studied, so 
also their flukes (Trematoda) and tapeworms (Cestoda). 
The porcupines (Hystricomorpha) of America (mostly tropical America) 

and of Africa. 
Edentata (sloths and anteaters) in South America, South Africa, southern 
India, Malaysia. 
Birds 

Struthiornidae (ostrich family) with species — 2 in New Zealand, 2 in 

Australia, I in Papua, 2 in South America, I in Madagascar. 
Trogonidae (the quetzal and its relatives) in South America, Central Amer- 
ica, Africa, and southern India. 
Chionidae (sheathbills) Antarctic Islands 
Psittacomorphae (parrots) in the Southern Hemisphere, with "stragglers" 

in North America and some in India. 
Paristeropodes (a group of fowls) in Australia and South America. 
The Ocydromine Rallidae (rails) 3 in Australia, Hcterochloa in New 

Zealand and also in Madagascar. 

Avocets and stilts in Australia, New Zealand, South America and Africa. 

Penguins in Australasia (including New Zealand and its Antarctic islands), 

South America, Africa, Antarctica, Antarctic islands in general, 

including St. Paul in the Indian Ocean. It is interesting to note 



28 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

that six species of fossil penguins were found in Graham Land by 
the Swedish Antarctic Expedition. In this connection note also that 
fossil Spheniscidae are known from New Zealand and Patagonia. 
Reptiles 

Giant tortoises in Galapagos Islands and in Malaysia. 
Amphibia 
Anura 

Leptodactylidae (southern frogs) in South America, Central America, 

West Indies, Australia, Tasmania, Papua, South Africa. 
Hylidae (tree frogs) in America (mostly tropical America), Australia, 
Tasmania, Papuasia, i species with several subspecies in Euro-Asia. 
Pipidae (Surinam toad, etc.) in Guiana and South Africa. 
Archaic Bufonidae, of other genera than Bufo, in Australia, north- 
western South America, Central America, tropical Africa, southern 
India, Ceylon, Malaysia. 
Gastrophrynidae, in Papuasia, tropical America, x^frica, Madagascar, 

southern India, Ceylon, Siam.* 
Dendrobatinae in northwestern South America, southern Central Amer- 
ica, western Africa, Madagascar. 
Urodeles 

Coeciliadae (blindworms) in tropical America, tropical Africa, southern 
India, Ceylon, western Malaysia. 
Freshwater fishes 

Ciclilidae in tropical South America, Central America, Cuba, Africa, Mada- 
gascar, southern India, Ceylon. 
Characinidae in tropical America and tropical Africa. 

Galaxiidae in New Zealand, Australia, South America, the Falkland Islands, 
southern Africa. The genus Galaxias occurs in New Zealand, 
Tasmania, southern Australia, the southern extremity of South 
America, the Falkland Islands. 
Osteoglossidae in South America and South Africa. 
Haplochitonidae in South America and South Africa. 
Dipnoi (lung fishes) in South .'\merica, tropical Africa, Australia. 
Molluscs 

Tertiary fossil species common to New Zealand and South America are 
named by Chilton (1909) as follows: Epitoniuni rugulosum lyra- 
tuni, Crepiditla gregaria, TuritcUa ambulacrum, Cucullaea alia, 
Venericardia patagonica, Brachydontes magellanica. This com- 
munity of species is of much interest and suggests a review of 
modern littoral mollusca and their parasites from the two regions. 
Arthropods 
Insects 

Ants — Notomynncs in New Zealand and Cliili, Prolasius in New Zea- 
land and its close relatives, Acanthoponcra and Lasiopharcs, in 
South America. The following annotation from Emery (1895) 
is worth noting : 

Chili is, however, an isolated country, which we may call " a con- 
tinental island," although it is not surrounded by water. If we should 
take the Chilian fauna as a standard for the primitive fauna of 

^ The report of a gastrophrynid from Samoa is questioned. 



NO. 8 PARASITES METCALF 29 

von Ihering's Archiplata, that should have been a very poor one, 
Hke the fauna of New Zealand, with which it offers a striking 
resemblance. The most characteristic feature of the Chilian ant 
fauna is the occurrence of peculiar species of Monomosium, like 
those inhabiting Australia and New Zealand, and of the genus 
Melophorus found only in Australia and New Zealand. These facts 
corroborate the hypothesis of a Cretaceous or Eocene connection 
between South America and Australia. 

New Zealand appears as a bit of old Australia, quite free from 
later Papuan or Indian intrusions, like Madagascar, which as an 
isolated part of old Africa, had received but a few immigrants, 
when, at the Pliocene epoch, a stream of Indian life entered into 
the Ethiopian continent. Probably Chili may be considered as a 
part of ancient Archiplata, secured from Guyanean and Brazilian 
immigrants by the heights of the Cordillera, but having preserved 
only an incomplete set of the original Archiplatean fauna. 

Beetles — Longicornia in Australia, New Zealand, South America ; 
Buprestidac in Australia, New Zealand, South America. 

Mies — Zaluscoides in the Auckland Islands ; the closely related genus 
Zalusca in Kerguelen. 

Peripatus — in Australia, South and Central America, South Africa, 
Peripafiis (scnsii strict 0) in South America and South Africa. 
Arachnoidea (spiders, etc.) 

Myro (a spider) with species — 2 in the Antarctic Islands of New Zea- 
land, I on Kerguelen Island, i at the Cape of Good Hope. 

Rubrins (a spider) Antarctic Islands of New Zealand, Tasmania, South 
America. 

Pacificana cockayii (a spider) in the Antarctic islands of New Zealand; 
a related species in Tasmania cUid a closely related species at 
Cape Horn. 

Cryptostcmma zvcstcrnmanni (?) in tropical America and tropical 
Africa. 

Cercoponius (a scorpion) in Australia, South America. 
Crustacea — Land and freshwater forms : 

Parastacid crayfishes in Australia, New Zealand, South America (with 
one " wanderer " in California), Madagascar. Their gill flukes have 
been studied by Harrison, so also their Histriobdellidae. 

Trichoniscus, a subantarctic genus. One species occurs in the subant- 
arctic islands of New Zealand, Fuegia, Falkland Islands. 

Defo in Australia, New Zealand, Chatham Islands, Auckland Islands, 
Chili, Cape of Good Hope, St. Paul Island. The species D. auck- 
Imidiac occurs in New Zealand and Chili. 

Jdotoca lacustris in New Zealand, Campbell Island, the Straits of 
Magellan. 
Annelid worms. Many of the commonest New Zealand polychaetous annelids 
are identical with those of Magellan Strait, Fuegia and Chili. A 
comprehensive study of these worms and their parasites from these 
regions should prove of much value. Chilton (1909) says "of 
13 species in the subantarctic islands of New Zealand only 2 are 
endemic in New Zealand, 8 are found in South America or the 
Falkland Islands, and 2 extend to Kerguelen ". 



30 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

Plants have not been studied through their parasites by the von 
Ihering method. On the chance of possibly interesting some botanists 
it may be worth while to list a few plants of interest in connection 
with southern dispersal. The forms listed seem to indicate : some a 
dispersal from northerly lands southward, but many more a dispersal 
eastward or westward between southern lands, some by way of Ant- 
arctica. Omitting less conspicuous forms, note the following ferns 
and flowering plants : 

Ferns 

Polytriclmin vcstituni — Australasia, South America, islands of southern 

Pacific Ocean. 
P. richardi — Australasia, Southern Pacific islands. 
Asplcnmm ftaccidum — Australasia, South America, Africa. 
Blechnum pcnamarlna — Australasia, South America. 
B. capense — Australasia, South America, Africa. 
Hcsteoptcris incisa — cosmospolitan in the tropics. 
Pteridium csciilcntum — Australasia, South America. 
Polypodiuin billardicri — Australasia, Malaysia, South America, Africa. 
HynicnophyUum ferrugineum — Australasia, South America. 
H. tunbridgcnsc — Australasia, South America, Africa. 

Dryoptcris punctata — Australasia, South America, islands ofif South Africa. 
Polystichuin adia)itifoniiac — Australasia, South America, southern Pacific 

islands. 
Asplenimn adiantoidcs — Australasia, Africa, islands of southern Pacific. 
Pocsia scabcnda — Australasia, Africa. 
Flowering plants 

Cypresses: Callitris in Africa, Madagascar, Australasia; Fit^roya in Qiile, 

Tasmania. 
Hierochloe rcdolctis (grass), Australasia, South America, southern Pacific 

islands. 
Monimiaceae : Tasmania, New Caledonia, New Zealand, Madagascar. 
Saxifragaceae- — 35 genera in Australasia, Madagascar, South Africa and 

South America, only 2 of which cross the equator. 
Proteaceae : 48 genera, 950 species in South America ; 32 genera, 250 species 

in South Africa. 
Verbenas : Petraea in South America, Timor, Java ; Pctracovitc.v, (a close 

relative) in Bouru and Amboina. 

Species common to Australasia and South America : 

Sedges as follows: Scirpus inundatus (extending to islands of the south 
Pacific), Carex danvinii, and its subspecies tirolepsis, C. trifida; Lunula 
racemosa; Lusiiriaga parziiHora (Liliaceae) ; Colohanthus qiiitensis; Crassula 
moschata; Gcum parviflonim; Sophora tctraptcra (the kowhai tree) ; O.valis 
magcllanica; Geranium scssiflorum ; Pelargonium australe, (New Zealand, 
Australia, Tristan da Cunha) ; Coriaria ruscifolia, C. thymifolia; Epilobium 
conjugens; Veronica elliptica. 



NO. 8 PARASITES METCALF 3I 



Genera common to Australasia and South America : 

Driinus (3 species in New Zealand, i in Tasmania, i in Fuegia, i Tertiarj- 
fossil, D. aniarctica, in Graham Land) ; Araucaria (i Australasian, 2 South 
American, Norfolk Island i. New Caledonia several, i fossil, A. imponens, in 
Antarctica, also 2 related fossils Araucaritis and Dadoxylon) ; Lomatia (6 
species in Australia and Tasmania, 3 in Chili, also 4 Tertiary fossil species in 
Antarctica); Embothryum (i Australian, 4 South American); Prionites (i 
each Tasmania and Fuegia) ; Eucryphis (i Tasmania, i Australia, 2 Chili) ; 
and others — Lepfocarpus, Orites, Aristolochia, Drapetcs, Tcrpnatia, Myosoiis, 
Phyllacciis, Lagenophora, Lcpt'mcUa, Enargea, Liizuriaga, Geranium, Azarella; 
Oreomyrrhis, Pcrncttia, Plantago (subgenus Plantaginella), Oreobolus, Carpha, 
Uncinia, Gaimarcia, Marsippospervmm, Roslkovia, Libertia, Nothophagus 
(Tertiary fossils, 4 species in Antarctica), Caltha {Psychrophila), Drosera 
(one subgenus), Eiicrypkia, Giinnera, Prionotes, Tetrachondra, Pratia, Donatio, 
Abrolanclla. 

Genera common to New Zealand and South America: 

GriscUna (4 species in Chili, 2 in New Zealand) ; Ourisia (19 in South Amer- 
ica, 8 in New Zealand) ; Discaria (18 in temperate South America, i in New 
Zealand, i in Australia); Gaya (10 in South America, i in New Zealand); 
Fuchsia (60 American from Mexico to Fuegia, 3 in New Zealand) ; Jovcllana 
(2 in Chili and Peru, 2 in New Zealand) ; Phrygilanthus (20 in South America, 
2 in New Zealand, 4 in Australia) ; Muehlenbcckia (10 in South America, 4 in 
New Zealand, 7 in Australia, one of them extending to New Zealand, I in the 
Solomon Islands) ; LaurcHa (2 in southern Chili, i in New Zealand, i fossil in 
Graham Land, Antarctica) ; Dacrydium (many in New Zealand, i in Chili) ; 
Pseiidopanax (5 in New Zealand, 2 in southern Chili). 

Two paragraphs from Cheesman (1909) might be quoted: 

Of 27 species of flowering plants and ferns known from the Kerguelen-South 
Georgia region, 20 are found also in the subantarctic islands of New Zealand 
while 27 are found in Fuegia and the Falkland Islands. The total number of 
Fuegian plants found in the subantarctic islands of New Zealand is 29, 14 of 
these extending also to the Kerguelen and South Georgia groups of islands. 
These figures deal only with the specific identity; if we consider the genera, 
we find that, out of 88 genera found in the subantarctic islands of New Zealand, 
there are no less than 56 with representatives in Fuegia. 

Eleven species of plants found in the subantarctic islands of New Zealand 
are found either in the Tristan da Cunha group in the South Atlantic or in the 
Amsterdam Island group in the Indian Ocean, the flora of these two groups 
possessing many points of agreement notwithstanding their wide separation and 
showing also undoubted traces of affinity with those of Fuegia and Kerguelen. 
Two of these 11 species, however, do not occur in Fuegia or the Kerguelen-South 
Georgia group of islands. 

What parasites, if any, can best be studied to test and extend the 
significance of the distribution of these and other southern hemisphere 
plants? Will they be some group or groups of fungi? Will predatory 



32 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 



insects of restricted food hal)its help? Will gall-forming insects give 
some light? How about nematodes? Will plant-feeding snails help? 

The last few pages have noted a few sources of data for but one set 
of problems connected with the biogeography of the Southern Hemi- 
sphere. There are many other problems and groups of problems. 
Let us mention only one other. 

It is thought that in Cretaceous times there was a strip of land 
running north from Japan, Korea and Kamchatka, crossing the 




Fig. 4. — Hypothetical composite map of the Pacific Ocean and adjacent 
lands during Cretaceous times, showing the land-strip bounding this ocean on 
the north and east and extending westerly from South America across the 
southern Pacific to Papua and Australia. Not all parts of this land-strip were 
in existence at any one time, the northern portions being mostly earlier, the 
South-Pacific bridge being later, perhaps early Tertiary. (Compiled from 
several authors, chiefly Arldt.) 



northern Pacific ( )cean and running down the west coast of America 
to Ecuador and the Galapagos Islands (fig. 4). This circumpacific 
land strip may have connected at its southwestern end with the 
northern Malayan region (cf. fig. 2). It is thought to have connected 
with Eastern Asia in perhaps luimerous places. It may have included 
the Aleutian Islands or may have lain mostly to the south of them. The 
mountainous islands of western Alaska, Vancouver Island, the Olympic 
mountains and the Siskiyou mountains of Northern California were 
prol)ably included ; so also may have been Mount Tamalpais, the Pre- 
sidio Hill, the southern California islands, the tip of Lower California 



NO. 8 PARASITES METCALF 33 

and the middle portion of Central America where the mountain ranges 
have an east and west trend. Upon the American portion of this 
circLimpacific land strip is a very interesting relict fauna and flora 
including, to name but a very few, the bell-toad Ascaphns (an immi- 
grant from Euro-Asia who brought with him his characteristic Euro- 
Asian bell-toad parasite, Protoopalina, of an ancient subgenus) and a 
number of plants, conspicuous among which are several pines — the 
Monterey Pine, the Torrey Pine, Pinus jeffreyi. Study of these 
western relict pines and their rust and other parasites and comparison 
with East Asian pines and their parasites might prove of much im- 
portance. We should remember, too, that the Peridermiums of pines 
produce lesions which should be recognizable if preserved as fossils. 

LITERATURE CITED 

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Cheesman, T. F. 1906. Manual of the New Zealand flora. 

1909. Systematic botany of the islands south of New Zealand. The 

Subantarctic Islands of New Zealand, Vol. I, Wellington, N. Z., John 
Murray, Govt. Printer. 

Chilton, Charles. 1909. The biological relations of the subantarctic islands of 
New Zealand. (Summary of results). The Subantarctic Islands of New 
Zealand, Vol. II, Wellington, N. Z., John Murray. Govt. Printer. 

Cockayne, L. 1907. Report on a botanical survey of Kapiti Island. Dept. of 
Lands, New Zealand Govt. 

1908. Report on a botanical survey of the Tongariro National Park. 

New Zealand Dept. of Lands. 

1908a. Report on a botanical survey of the Waipoua Kauri Forest. New 

Zealand Dept. of Lands. 

1910. New Zealand plants and their story. N. Z. Board of Science and 

Art, Manual No. i, Wellington. John Murray, Govt. Printer. This edition 
is preferable to the later one. 

1921. The vegetation of New Zealand. W. Engelmann, Leipzig. 



Darling, S. J. 1921. The distribution of hookworms in the zoological regions. 
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1925. Comparative helminthology as an aid in the solution of eth- 
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Dunn, E. R. 1925. The host-parasite method and the distribution of frogs. Th.c 

American Naturalist, Vol. 59, No. 663, July-August. 
Emery, C. 1895. On the origin of European and North American ants. Nature, 

Vol. 52, Aug. 22. 
Ewing, H. E. 1924. On the taxonomy, biology and distribution of the biting 

lice of the family Gyropidae. Proc. U. S. Nat. Mus. Vol. 63, Mch. 4. 

1924a. Lice from human mummies. Science, Vol. LX, No. 1556. 

1926. A Revision of the American lice of the genus Pediculns, together 

with a consideration of the significance of their geographical and host dis- 
tribution. Proc. U. S. Nat. Mus., Vol. 68, June 10. 



34 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

Forbes, H. O. 1893. The Chatham Islands. Their relation to a former southern 

continent. Abstract in Nat. Sci. Vol. 3. 
Gadow, Hans. 1909. Amphibia and Reptilia. Cambridge Natural History. 
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stract in Ann. Rep. Sydney Univ. Sci. Soc, 1911-1912. 

1914- The Mallophaga as a possible clue to bird phylogeny. Austral. 

Zoologist, Vol. I, No. I. 

1915. Mallophaga from Apteryx, and their significance. Parasitology, 

Vol. 7, No. I. 

— ■ 1915a. The relation of the phylogeny of the parasite to that of the host. 

Abstract in Rep. Brit. Assoc. Adv. Sci., 1915. 
1916. Bird-parasites and bird-phylogeny. Ibis, April, 1916. Abstract 

and discussion in Bull. CCXII. Brit. Ornith. Club. 

1922. On the Mallophagan family Trimenoponidae, with a description 

of a new genus and species from an American marsupial. Austral. Zoologist, 
Vol. 2, No. 4. 

1924. The migration route of the Australian marsupial fauna. Austral. 

Zoologist, Vol. 3, No. 7. 

1926. Crucial evidence for antarctic radiation. Amer. Naturalist, Vol. 60. 

1928. On the genus Strafiodrilits. Records Austral. Mus., Vol. 16. 

1928a. Host and parasite. Presidential address. Proc. Linn. Soc. New 

South Wales. 1928, No. i. 

" in press " in 1928. The composition and origins of the Australian fauna, 



with special reference to the Wegener hypothesis. Rep. Austral. Assoc. Adv. 

Sci., Perth, 1926. 
Hegner, R. W. 1928. The evolutionary significance of the protozoan parasites 

of monkeys and man. Quat. Rev. Biol., Vol. 3, No. 2, June. 
Ihering, H. von. 1891. On the ancient relations between New Zealand and 

South America. Trans. & Proc. New Zea. Inst., Vol. 24. 

1902. Die Helminthen als Hilfsmittel der zoogeographischen Forschung. 

Zool. Anzeig., Vol. 26, Oct. 27. 

Johnston, S. J. 1913. Trematode parasites and the relationships and distribu- 
tion of their hosts. Rep. Austral. Assoc. Adv. Sci., Melbourne. 

1914. Australian trematodes and cestodcs ; a study in zoogeography. 

Med. Journ. Austral., Sept. 12. Abstract in Proc. Brit. Assoc. Adv. Sci., 
Australia. 

1916. On the trematodes of Australian birds. Proc. Roy. Soc. N. S. 

Wales, Vol. i. 

Kellogg, Vernon L. 1896. New Mallophaga, I. Proc. Calif. Acad. Sci., Vol. 6. 

1905. Insects. New York, Henry Holt. 

• 1913. Distribution and species-forming of Ectoparasites. Amer. Nat- 
uralist, Vol. 47. 

— 1913a. Ectoparasites of the monkevs, apes and man. Science, N. S., 

Vol. 38. 

1914. Ectoparasites of mammals. Amer. Naturalist, Vol. 48, May, 1914. 



Kellogg & Kuwana. Mallophaga from birds Proc. Wash. Acad. Sci., Vol. 4, 

Sept. 30. 
Longman. 1924. The zoogeography of marsupials. Mem. of Queensland Mus., 

Vol. 8, No. I, Jan. 30. 



NO. 8 PARASITES METCALF 35 

Matthew, W. D. 1915. Climate and evolution. Ann. N. Y. Acad. Sci., Vol. 24, 

Feb. 18. 
Metcalf, M. M. 1920. Upon an important method of studying problems of 

relationship and of geographical distrilnition. Proc. Nat. Acad. Sci., Vol. 6, 

No. 7, July. 

1922. The host-parasite method of investigation and some problems to 

which it gives approach. Abstract in Anat. Record, Vol. 23, No. i, January. 

1922. Animal distribution and ancient distribution routes. Lectures 

upon evolution and animal distrilnition, Univ. Buffalo Studies, Vol. 2, 
No. 4, Dec. 

— 1923. The opalinid ciliate infusorians. Bull. 120, U. S. Nat. Mus., 

June 15. 
— - 1923a. The origin and distribution of the Anura. Amer. Naturalist, 

Vol. 57. Sept. -Oct. 
— — — 1923b. The host- parasite method and problems in which it is useful. 

Abstract in Anat. Record, Vol. 26, No. 5, Dec. 20. 
— 1924. The opalinid parasites and the geographical distribution of the 



bell-toads (Discoglossidae), with a criticism of the age and area hy- 
pothesis. Abstract in Anat. Record, Vol. 29, No. 2, Dec. 28. 

— 1926. Larval stages in a protozoon. Proc. Nat. Acad. Sci., Vol. 12, 
No. 12, Dec. 

— 1928. The liell-toads and their opalinid parasites. Amer. Naturalist, 
Vol. 62, Jan.-Feb. 

— 1928a. Trends in evolution. A discussion of data bearing upon " ortho- 



genesis." Journ. Morphol. & Physiol., \'ol. 45, No. i, March 5. 
MooDiE, R. L. 1923. Paleopathology. L^niv. Chicago Press. 
Noble, G. K. 1922. The phylogeny of the Salientia. Bull. Amer. Mus. Nat. 

Hist.., Vol. 46. 
19-5- The evolution and dispersal of frogs. Amer. Naturalist, Vol. 59, 

May-June. 
Oliver, W. R. 15. 1925. Biogeographical relations of the New Zealand region. 

Journ. Linn. Soc, Vol. 47, No. 313, Sept. 16. 
Ortmann, a. E. 1896-1899. Tertiary invertebrates. Rep. Princeton Univ. 

Expedition to Patagonia. 
1901. Theories of origin of Antarctic fauna and flora. Amer. Naturalist, 

Vol. 35- 

1902. The geographical distribution of freshwater decapods and its 



bearing upon ancient geography. Proc. Amer. Philos. Soc, Vol. 41, No. 171, 
April-Dec. 

RuFFER, M. A. 1921. Paleopathology of Egypt. Univ. Chicago Press. 

ScHENCK, H. 1905. Ueber Flora und Vegetation von St. Paul und Neu Amster- 
dam. Wiss. Ergeb. Deutch. Tiefsee-Expedition, Vol. 2, T. i. Lief i. 

1905a. Vergleichende Darstellung der Pflanzengeographie der sub- 

antarktischen Inseln inbesonders ueber Flora und Vegetation von Kerguelen. 
Same reference as Schenck (1905). 

1907. Beitrage zur Kenntniss der Vegetation der Canarischen Inseln. 



Lief. 2, of same publication as Schenck (1905). 
Skottsberg, Carl. 1915. Notes on the relations between the floras of subant- 
arctic America and New Zealand. Plant World, Vol. 18, No. 5, May. 



36 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 81 

Ward, H. B. 1926. The needs and opportunities in parasitology. Science, 

Vol. 64, No. 1654. Sept. 10. 
Wenyon, C. M. 1926. Protozoology. London, Bailliere, Tindall & Cox. 
Wheeler, W. M. 1927. The ants of Lord Howe Island and Norfolk Island. 

Proc. Am. Acad. Arts & Sci., Vol. 62, No. 4. May. 
Williams, H. U. 1909. The epidemic of the Indians of New England, 1616- 

1620, with remarks on native American infections. Johns Hopkins Hospital 

Bull., Vol. XX, Nov. 
ZscHOKKE, F. 1899. Neue Studicn an Cestoden aplacentaler Sangetiere. 

Zeitsch. f. w. Zool. Bd. 65, Heft 3, Feb. 14. 
1907- Moncsia diaphana n. sp. Ein weiterer Beitrag zur Kenntniss der 

Cestoden aplacentaler Sangetiere. Central bl. f. Bakt., Vol. 44. 



M 



II 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 

VOLUME 81, NUMBER 9 



A SECOND COLLECTION OF MAMMALS 
FROM CAVES NEAR ST. MICHEL, HAITI 



(With Tem Plates) 



BY 

GERRIT S. MILLER, JR. 

Curator, Division of Mammals, C S. National Museum 




(Publication 3012) 



CITY OF WASHINGTON 

PUBLISHED BY THE SMITHSONIAN INSTITUTION 

MARCH 30, 1929 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOLUME 81, NUMBER <» 



A SECOND COLLECTION OF MAMMALS 
FROM CAVES NEAR ST. MICHEL, HALIT 



(With Ten Plates) 



BY 

GERRIT S. MILLER, JR. 

Curator, Division of Mammals, U. S. National Museum 




(Publication 3012) 



CITY OF WASHINGTON 

PUBLISHED BY THE SMITHSONIAN INSTITUTION 

MARCH 30, 1929 



BALTIMORE, MD., U. 8. A. 






A SECOND COLLECTION OF MAMMALS FROM CA\^ES 
NEAR ST. MICHEL, HAITI 

By GERRTT S. MILLER, JR. 

curator, division of mammals, u. s. national museum 
(With io Plates) 

Six years ago I published a short account of some bones of mammals 
from the floor material of two caves situated near St. Michel, north- 
centrar Haiti (Smithsonian Misc. Coll.. Vol. 74, No. 3, pp. 1-8, 
October 16, 1922). The small collection on which that paper was 
based had been made in 192 1 by Mr. J. S. Brown and Mr. W. S. 
Burbank with the object of determining whether the caves contained 
deposits sufficiently rich in the remains of extinct vertebrates to justify 
a special expedition for their careful study. The few specimens brought 
home proved to be of so much interest that I visited Haiti in the 
spring of 1925, spending about four weeks at the plantation of 
I'Atalaye near St. Michel. A general account of this field-work ap- 
peared in Smithsonian Miscellaneous Collections, Vol. 78. No. i, pp. 
36-40, April 8. 1926. The following pages contain descriptions of the 
remains of mammals which I collected. 

Concerning the caves themselves there is nothing important to add 
to the notes made by Mr. Brown and Mr. Burbank. Two smaller 
caves were found close to the large cavern near the town of St. Michel. 
One of these has the entire roof fallen in so that very little of the 
original floor material could be investigated. The other was in good 
condition for working, and the deposits which it contained proved 
to be exceptionally rich. Locally the region in which this group of 
caves is situated is known as St. Francisque. The cave in the dry 
valley north of the Atalaye plantation had been completely worked 
out for guano since it was examined by Mr. Brown and Mr. Burbank. 
Thus the interesting bone deposit which it contained had been almost 
totally destroyed. Nevertheless I succeeded in finding a few speci- 
mens scattered among the sifted limestone fragments with which the 



* Not " at the northwest end " of the republic as I wrongly stated in my 
general account of the region. 

Smithsonian Miscellaneous Collections, Vol. 81, No. 9 

I 



2 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

floor is now covered to a depth of nearly lo feet. On the top of 
the ridge bounding the west side of this valley are situated at least 
three caves which had not been previously examined. One of these 
has no opening other than a hole in the roof about 6 x lo feet in 
diameter. The chamber beneath this hole appeared to extend down- 
ward more than 20 feet. Its lateral extent could not be determined, 
and I made no attem]it to explore it. One of the other caves is 
unusually dee]), while the third is of more normal form, but rather 
narrow and crooked. In both I found abimdant remains of extinct 
mammals. 

In all of these caves the deposits began at or near the surface and 
continued downward to a depth of about four feet. The bones then 
ceased, and further digging proved so fruitless that it was nowhere 
continued to rock bottom. Wherever bones occurred the deposit could 
be discovered in a few minutes' work with shovel or trowel ; and at 
any spot where the first few minutes' digging revealed nothing the 
result of further excavation to a depth of six feet was fruitless. 
Mr. Brown and Mr. Burbank had previously found this to be the case. 

Before going to St. Michel I spent a day working in a cave at 
Diquini. near Port-au-Prince. The conditions there appeared to be 
exactly the same as in the large cave at St. Francisque, but no bones 
were found other than a few remains of domestic goat and pig in 
the most superficial layers, and recent bats and introduced rodents 
in fresh owl pellets. Why this cave should have been barren of the 
extinct fauna which occurs so abundantly in those near St. Michel 
is a question to which I cannot suggest an answer. 

Since this paper was written the St. Michel caves have been again 
visited in the interests of the National Museum. The generosity of 
Dr. W. L. Abbott enabled Mr. Arthur J. Poole, Scientific Aid, Divi- 
sion of Mammals, to spend the period from December 15. 1927. to 
March 15, 1928. in carrying on excavations which have probably re- 
sulted in exhausting the bone deposits. Inspection of the very rich 
material which he brought back to Washington shows that, in general, 
these new collections confirm the conclusions which I had reached 
after studv of the specimens that I obtained myself. Such additional 
facts as they bring to light pertain chiefly to details concerning some 
of the new forms which I had already described in manuscript. I 
have therefore concluded to publish this paper as it was originally 
written, except for the account of the ground sloths, animals for 
whose understanding my material proves to have l)een so inadequate 
as to have led to conclusions which I now believe to have been wrong. 



NO. 9 MAMMALS FROM CAVES IN HAITI MILLER 3 

INSECTIVORA 

Insectivures of the ;^eiuis Ah\s'of^h()ntes are al)iin(lantly represented 
in the Haitian caves. They have not previously been recorded from 
the island of Hispaniola. In the superficial layer of the cave floors 
the bones of these animals occur in undisturbed material along with 
remains of Epimys raftiis and Miis iiiiisciiliis. This association is so 
intimate that there appears to be no reason to doubt the simultaneous 
occurrence of the insectivores and the introduced rodents. Some of 
the jaws of A'esophoiifcs are more fresh in appearance than some of 
the jaws of Rattus near which they were found. Whether or not 
Nesophontcs now exists alive is a question which for the present 
cannot be answered. No bones of insectivores have been found in 
any of the numerous fresh owl pellets which I have examined. It 
seems not improbable, however, that if any part of the island remains 
uninvaded by the roof rat, the iiative animal might now be found 
to exist there. 

It is a noteworthy fact that up to the present time no remains 
of Solenodon have been found in an\ of the caves. This animal is so 
much larger than Nesophontcs that its absence from deposits which 
are mostly owl -made might at first be thought to be due to this 
circumstance. Its size, however, is no greater than that of several 
of the rodents which were freely eaten by the extinct giant barn owl, 
of whose refuse the bone deposits chiefly consist. While it is there- 
fore impossible to suggest any reasonable explanation of the absence 
of Solerwdon bones, the fact of this absence is an important one 
because of its bearing on the question of the completeness of the 
faunal record preserved in the caves. 

NESOPHONTES PARAMICRUS sp. nov. 

Plate I, fig. I 

Type. — Skull, lacking ])ostero-inferior portion of occiput; the fol- 
lowing teeth in place: piir, piii*. in^ and vr of right side, m^ and nr 
of left side. No. 253063, U. S. Nat. Mus. Collected at front of 
large cave near St. Michel, Haiti, March, 1925, by Gerrit S. Miller, Jr. 

Diagnosis. — Size and general characters of skull and teeth as in 
the Cuban Ncsophontes inicnis G. M. Allen. Upper molars without 
the well-defined sulcus which, in A^ inicnis, lies between the base of 
metacone and posterior commissure of protocone ; lower molars with 
metaconid and entoconid obviously less nearly terete than in the 
Cuban animal. 



4 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

Skull. — The skull appears to be similar to that of Ncsophohtes 
micrus. 

Teeth. — As compared with those of Nesophontes micrus the larger 
maxillary teeth are more robust in general form, a character resulting 
from the less rapid narrowing of the base of the protocone toward 
the lingual side of the tooth crown. This peculiarity is especially 
evident in m^ and in'-, but it is also visible in pm*. This general 
tendency toward robustness of the cusps appears to be responsible 
for the main dental peculiarity by which the Haitian and Cuban 
members of the genus are distinguished from each other. In 
Nesophontes micrus there is always present, up to the time when 
this portion of the crown is destroyed by wear, a distinct and often 
wide notch at the point where the posterior margin of the protocone 
joins the base of the metacone. In A', parandcrus the bases of the 
two cusps are so large and well filled-out that they come together 
directly and smoothly or with at most a faintly developed intervening 
transverse crease. The same general features are present in the 
mandibular teeth, where the cusps show a uniform tendency to be 
heavier and less nearly terete than in the Cuban animal, characters 
best appreciated on comparison of the mataconid and entoconid of 
the two species. The heels of the lower molars are quadrangular 
(longer than broad) rather than squarish in outline and the bottoms 
of the central convexities tend to be rather broadly rounded instead 
of narrowly infundibuliform. 

Measurements. — Type: greatest length, 32.4 ± ; palatal length, 
15.0; glenoid breadth, 12.4; interorbital breadth, 7.4; palatal breadth 
including molars, 9.2; front of canine to back of ur, 12.2; four 
molariform teeth (alveoli), y.2. 

Specimens examined. — Skulls, 2; left maxilla, i; mandibles, 18; 
humeri, 9; femora, 10; innominate, i. 

Remarks. — This species is sharply differentiated from the Porto 
Rican A^ edithce by its much smaller size, and from the Cuban 
A^. micrus by the j^eculiarities of its teeth. 

NESOPHONTES HYPOMICRUS sp. nov. 

Plate I, fig. 2 

Type. — Nearly perfect skull (lacking auditory parts, incisors, 
canines and right median premolar) No. 253077, U. S. Nat. l\fus. 
Collected in the deep cave near the Atalaye plantation, Haiti, March, 
1925, by Gerrit S. Miller, Jr. 



NO. 9 MAMMALS FROM CAVES IN HAITI MILLER 5 

Characters. — Like Nesophontcs paramicrns but constantly smaller 
(see pi. I and detailed comparisons under "remarks") ; triangular 
outline of m^ and ;;;- in palatal aspect narrower ; heels of mandibular 
molars shorter, their concavities narrowly funnel-shaped at base as 
in ^V. micriis. 

Skull. — Except for its smaller size the skull appears to be essen- 
tially similar to that oi N. paramicrns. 

Teeth. — The upper teeth in four individuals differ constantly from 
the two specimens oi N. paramicrns in the narrower triangular outline 
of the crowns of /;/' and iir. In the mandibular teeth the heel of 
each molar is shorter, though this character is usually more 
pronounced in iih and tiio than in nis. 

Measurements.— Type : greatest length. 27.6 ; condylobasal length, 
26.8; palatal length. 12.8; glenoid breadth, 10.6; interorbital breadth, 
5.8; palatal breadth including molars, 7.2; depth of braincase 
(median). 6.4; fronto-palatal depth l)ehind molars, 5.2; front of 
canine to back of ;/;^, 9.8; four molariform teeth (alveoli), 6.0. 

Spceinieiis examined. —SkuWs, 4; left maxilla, i; mandibles, 24; 
humerus, 1 ; femora, 6 ; innominates, 3. 

Remarks. — That the original series of Nesophontes skulls from 
Porto Rico presents a range of variation in size which is unprec- 
edented among other dilambdodont insectivores is well known. This 
fact has been attril)uted to sexual dimorphism and as such has been 
made a part of the diagnosis of the family Nesophontidce (see 
Anthony, Mem. Amer. Mus. Nat. Hist., n. s., Vol. 2, p. 365 " June " = 
October 12, 1918; Bull. Amer. Mus. Nat. Hist., Vol. 41, pp. 633, 
635. December 30, 1919). The same conditions, though less well 
marked, were noticed by Anthony in a series of 33 skulls and 150 
mandibles of the Cuban Nesophontes micrus (Bull. Amer. Mus. Nat. 
Hist., Vol. 41, p. 633, December 30, 1919). Through Mr. Anthony's 
kindness I have had the opportunity to examine the entire series of 
Nesophontes jaws in the American Museum of Natural History, and 
as the result of this examination I am convinced that the differences 
in size shown by the Cuban and Porto Rican series are probably not 
due to the same causes as those which have produced the analogous 
dift'erences that occur in the Haitian material. 

Among 26 jaws of the Porto Rican Nesophontes edithce in suffi- 
ciently good state of preservation to give the two most important 
measurements, namely, distance from articular process to anterior 
face of first molar, and depth through coronoid process, these vary 
from 16.2 to 22.2 mm. and from 9.0 to 13.2 mm. respectively. This 



6 SMITHSONIAN M ISCKIJ.ANEOrS COLLECTIONS VOL. 8l 

is an unusually wide range of variation, but the steps by which it is 
accomplished are so small and the numbers of individuals are so 
evenly spaced along the series that the measurements present no 
features which suggest the inclusion of two species. The same is 
true of 48 jaws of the Cuban Nesopliontes inicrus. Here the range 
of variation in length from articular process to front of Wi is from 
12.2 to 14.6 mm. and that in coronoid depth is from 6.0 to 8.8 mm. 
One individual (teeth slightly worn) appears to be abnormally small, 
with the measurements ii.o and 5.8 respectively ; but apart from this 
exception the variations are remarkably uniform, and again there is 
nothing to suggest anything else than purely individual variation. 

The series of 42 jaws from Haiti, in striking contrast, is readily 
separable into two lots on the basis of either one of three different 
measurements:' (a) distance from articular process to front of Wi, 
larger form (13 specimens), 13.2- 14.0, smaller form ( 18 specimens), 
10.0- 1 1.6 ; (b) depth through coronoid process, larger form ( 15 speci- 
mens), 7.6-8.8, smaller form (17 specimens), 6.0-7.0; (c) combined 
length of nil and 1112, larger form (12 specimens), 4.50-4.85, smaller 
form (20 specimens), 3.70-3.85. The teeth in the smaller form are 
definitely reduced in size as com])ared with those of the larger indi- 
viduals, a character which is immediately appreciable on comparison 
of specimens. In the Cuban and Porto Rican series the teeth tend to 
remain more constant throughout the series. Therefore in those 
smaller Cuban jaws which approach in size the maximum of the 
smaller Haitian form the teeth are obviously larger than in the latter. 
Finally there is no difference in the structure of the heel in the teeth 
carried by the large and small Porto Rican or Cuban jaws, while in 
the Haitian specimens an obvious diiference is present.^ Turning now 
to the skull and the maxillary dentition we find that the contrasts in 
size between the extremes of specimens from Cuba is about the same 
as that seen in those from Haiti. The teeth from Cuba, however, 
are alike in form from the largest to the smallest of 13 specimens, 
while in those from Haiti there is an obvious difiference in the form 
of the triangular crown outline in the two largest as compared with 
five others. A final interpretation of these facts must await the 



' Owing to the fact that some of the mandibles are imperfect it is impossible 
to obtain all three nieasurements from every individual. 

^ This is so constant that I made only one error in identifying, by this char- 
acter alone, 26 jaws (18 Iiypouiicriis and 8 paramicrus) submitted to me one 
at a time by an assistant. The specimens were examined under a magnifying 
power with which I was unfamiliar, this having the effect of destroying all 
sense of relative size. 



NO. 9 MAMMALS FROM CAVES IN HAITI MILLER 7 

accuniulation of much more abundant material; but it now appears 
obvious that the variation in Haitian Nesophontes is different in char- 
acter from that which is presented by the members of the genus 
occurring in Porto Rico and Cuba, and that the course which does 
least violence to probability may be followed by recognizing two 
species among the larger Haitian specimens, separated from each 
other by absolute differences in size and by easily appreciable 
structural characters of both maxillary and mandibular molar teeth, a 
condition which is not known to be due to sexual dimorphism in 
any insectivore. 

NESOPHONTES ZAMICRUS sp. nov. 

Plate I, fig. 3 

Type. — Anterior part of skull with coni])lete palate ( teeth lacking 
except pin- left and the molariform teeth of both sides) No. 253090, 
U. S. Nat. M*is. Collected in large cave near St. Michel, Haiti, March, 
1925, by Gerrit S. Miller, Jr. 

Characters. — Size much less than in any hitherto known member 
of the genus; palatal length, 10.6; four largest maxillary teeth, 5.0; 
four largest mandibular teeth, 5.6. 

Skull. — Except for their smaller size the two imperfect skulls of 
this animal do not show any appreciable characters by which they 
can be distinguished from those of Nesophontes hypomicrus. The 
type gives the impression of greater slenderness, but this may be due 
to its small actual size. The ratio of palatal width to palatal length 
in the type is 54.7 and of palatal depth (at posterior margin) to 
palatal length is 37.7. In both of the two skulls of M. hypomicrus these 
ratios are 55.4 and 40 respectively, a difference which appears to be 
\^hin the limits of reasonably looked-for individual variation. A 
greater difference is seen in the ratio of length from hamular process 
to depth including hamular process : 39.3 in A'', zamicrus, 42.7 in 
A'^. hypomicrus. Still greater is that between the ratio of rostral width 
at level of canine to palatal length : 24.5 in A'', zamicrus, 30.7 in 
A^ paramicrus. Whether or not these peculiarities are anything more 
than individual is a question which must for the present remain open. 

Teeth. — The teeth, except for their smaller size, resemble those 
of Nesophontes hypomicrus in all the characters which distinguish 
this animal from A'^. paramicrus. 

Measurements. — Type: palatal length, 11. o; glenoid breadth, 7.8; 
interorbital breadth, 5.0 ; palatal breadth including molars, 5.8 ; front 
of canine to back of w^ 8.2; four molariform teeth (alveoli), 5.0. 



8 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

Two mandibles : articular process to front of nii, 9.0 and 8.8 ; depth 
through coronoid process, 4.8 and 4.6 ; four molariform teeth (alveoli), 
5.2 and 5.2. 

Specimens exauiined. — Anterior portion of skull, i (type) ; median 
portion of skull (rostrum broken away at level of pin*), i ; mandibles, 
2 ; humerus, i . 

Remarks. — In their extremely small size the specimens which I 
refer to Nesophontes zamicrus are sharply set off from all the other 
material which I have examined. In the type and one mandible the 
teeth are just beginning to wear ; in the second skull and second jaw 
the process is distinctly more advanced. The series of N. hypomicnis 
includes individuals representing exactly the same stages but showing 
no approach to the diminutive size of the smallest animal. 

CHIROPTERA 

Many bones of bats occur in the deposits. While some of these 
must have come from individuals which inhabited the caves and died 
there, most of them were probably dropped in owl pellets. The species 
are all, with one exception, known to be present inhabitants of the 
island. The one exception is a local form of a genus not hitherto 
found living elsewhere than in Cuba. There is no reason to suppose 
that it is extinct in llispaniola. 

CHILONYCTERIS PARNELLII PUSILLUS G. M. Allen 

( )ne skull from owl pellets in the cave at Diquini. 

MORMOOPS BLAINVILLII CINNAMOMEA (Gundlach) 

Three skulls from the larger cave near St. Michel. All in superficial 
(le])()sit. one of them in a fresh owl pellet. 

MACROTUS WATERHOUSII WATERHOUSII Gray 

Three skulls and five mandibles from the large cave near St. Michel. 
( )ne mandible from the small cave. All in su])erficial (le])()sits. Four 
skulls from owl ])ellets in the cave at l)i<|uini. 

MONOPHYLLUS CUBANUS FERREUS Miller 

A skull, lacking all the teeth except ni^ right and pni^ and ni^ left, 
was found among the owl pellet material from the cave at Diquini. 

This specimen is unique among the many skulls of Monophyllus 
which I have examined in possessing the well-developed alveolus of a 



NO. 9 MAMMALS FROM CAVES IN HAITI MILLER 9 

simple premolar immediately behind the alveolus of the canine. The 
cavity is closely crowded between the alveolus of the canine and that of 
the anterior root of the normal anterior premolar. Its diameter is 
about .25 mm. In other respects the skull does not differ appreciably 
from those collected by Dr. W. L. Abbott at Jeremie. 

Measurements. — Greatest length, 21.4; condylobasal length, 20.0; 
zygomatic breadth, 9.0 ; breadth of braincase, 8.8 ; postorbital con- 
striction, 4.0 ; breadth of rostrum across alveoli of canines, 3.8. 

BRACHYPHYLLA PUMILA Miller 

One skull from the steep cave near the Atalaye plantation. Its 
measurements are as follows : greatest length, 28.0 ; condylobasal 
length, 26.8 ; zygomatic breadth, 15.8 ; lacrimal breadth, 9.0 ; postorbital 
constriction, 6.2; breadth of braincase, 12.2; depth of braincase at 
middle, 9.6 ; mandible 19.0 ; maxillary toothrow (alveoli), 9.2 ; greatest 
width of palate including molars, 10.4 ; mandibular toothrow (alveoli) , 
10.2. This specimen and the two originally collected by Dr. W. L. 
Abbott near Port-de-Paix shows that the Haitian Brachyphylla is 
readily distinguishable from the large form inhabiting Porto Rico. 
From the small Cuban B. tuina it appears to differ in slightl}- less 
reduced size, broader rostrum and palate, and larger molars. 

ARTIBEUS JAMAICENSIS JAMAICENSIS Leach 
Seven mandibles from the large cave near St. Michel, six skulls 
and nine mandibles from the deep cave near the Atalaye plantation and 
three skulls from owl pellets in the cave at Diquini. 

A large colony occupied the crooked cave in the group near the 
Atalaye plantation. When disturbed by the noise made by workmen 
digging in the cave floor the bats soon took refuge in small holes in 
the roof, where they remained almost completely hidden. On one 
occasion a half-grown young, unable to fly, fell from a roof cavity 
to the ground near where we were excavating. As it lay helpless it 
uttered chirping, bird-like cries. Immediately the air was filled with 
dozens of plunging and rising adult bats behaving in the manner of a 
flock of terns hovering over a wounded companion. Not one of them 
actually touched the young animal, and the confusion soon subsided, 
the adults retiring again to their holes. 

PHYLLOPS HAITIENSIS (J. A. AUen) 

Ten skulls, one left maxilla, 7 mandibles from the large cave near 
St. Michel ; one skull from the deep cave and one mandible from the 



lO SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

crooked cave near the Atalaye plantation. One skull from owl pellets 
in the cave at Diquini. The skulls were found at all levels from the 
surface downward to a depth of about two feet. 

EROPHYLLA SANTACRISTOBALENSIS (Elliot) 

One skull and two mandibles from the large cave near St. Michel ; 
two skulls and three mandil)les from the deep cave near the Atalaye 
]:)lantation. The skulls exactly resemble three collected in a cave near 
Port-de-Paix by Dr. W. L. Abbott. 

In cranial characters this species resembles Erophylla bomhifrons 
of Porto Rico and differs notably from the Cuban E. sczckorni and 
its relatives E. syops of Jamaica and E. planifroiis of the Bahamas. 
The close correspondence in size between the skulls of E. santacristo- 
bolcnsis and E. bomifrons is shown by the following measurements 
of the three best Haitian specimens (a) compared with those of three 
skulls from Porto Rico (b) : greatest length, (a) 24.0, 23.4, 23.4. 
(b) 24.0, 24.2, 24.4; condylobasal length, (a) 22.2, 22.0, 22.0, (b) 
22.2, 22.4, 22.4; breadth of braincase, (a) 9.6, lO.o, lo.o, (b) lo.o, 
10.4. lo.o; postorbital constriction, (a) 4.6, 4.4, 4.6, (b) 4.4, 4.6, 4.6; 
breadth of rostrum at base of canines, (a) 5.0, 5.0, 4.8, (b) 5.0, 5.2, 
5.0; median depth of braincase, (a) 8.4, 8.0, 8.0, (b) 8.0, 8.2, 8.2. 
Comparison of specimens shows that the rostrum in the Haitian 
animal is smaller relatively to the braincase than it is in Erophylla 
bonibifrons, and further material will undoubtedly demonstrate the 
specific distinctness of the two animals. 

PHYLLONYCTERIS OBTUSA sp. nov. 

Type. — Imperfect skull No. 253095, U. S. Nat. AIus. Collected in 
the crooked cave near the Atalaye plantation, about four miles east 
of St. Michel, Haiti, March, 1925, by Gerrit S. Miller, Jr. 

Characters. — Like the Cuban Phyllonyctcris paeyi but incisive 
foramina smaller and anterior border of premaxillaries as viewed in 
palatine aspect less narrowly curved. 

Skull and teeth. — The size of the skull is essentially as in 
Phyllonycteris poeyi, though the average ma}- ])rove to be above that 
in the Cuban animal when it is possible to compare adequate series of 
specimens. The structure of the anterior part of the palate is alike in 
the three specimens examined, and is not duplicated by anv among 
the large number of Cuban skulls with which I have compared them. 
Taking the width of the palate between the incisors and canines as 



NO. 9 MAMMALS FROM CAVES IN HAITI MII.LER II 

lOO, the length of this rei^ioii from front of premaxilla to posterior 
border of foramina averages about 82 in Phyllonyctcris poeyi, while 
in the three specimens of P. ohtusa it is only 56.6, 58. and 59.5. 
respectively. The curve of the anterior premaxillary border of the 
palate forms part of a circle which, if completed posteriorly, would 
pass close behind the foramina in P. poeyi, but in P. ohtusa it would 
be so much larger that the hinder edge of the foramina would scarcely 
extend beyond its center. The mandible and the molars, both maxillary 
and mandibular, do not differ a])precial)ly from those of P. pncyi. 
Other teeth lost. 

Measurements. — Type and si)ecimen from Diquini (No. 253096) : 
greatest length, - — , 22.2; palatal length, lo.o, 10.2; back of glenoid 
process to front of premaxillary. 17.2, 16.8; breadth of braincase, 
— , 10.2; postorbital constriction. 5.6. 5.4, width of palate including 
molars, 7.2. 7.0; mandible. — . 15.4; maxillary toothrow (alveoli). 
7.0, y.2\ mandibular toothrow (alveoli), — , 8.0. 

Specimens examined. — A skull and mandible from the crooked cave 
near the Atalaye plantation, a skull from a cave near Port-de-Paix 
(Dr. W. L. Abbott), and a skull from owl pellets found in the cave 
at Diquini. 

Remarks. — Unlike its relative ErophyUa the Haitian PhyUonycteris 
is not particularly like the Porto Rican member of its genus. As 
Anthony figures (Mem. Amer. Mus. Nat. Hist., n. s., Vol. 2, pi. 60. 
fig. 12) and describes the Porto Rican P. major it is a larger animal 
with relatively small teeth; palatal length ranging from 10.6 to ii.i. 
but with a toothrow of only 6.7 to 6.8. 

EPTESICUS HISPANIOL^ Miller 
TADARIDA MURINA (Gray) 

One mandible of each of these small bats was collected in the large 
cave near St. Michel. 

RODENTIA 

P>ones of native rodents representing six genera, only one of which 
is known to have a living species, form the great mass — probabl} 
more than 95 per cent — of all the deposits. Mingled with them are 
the remains of the large owl, Tyto ostologa, which brought them to 
the caves. It is easy to realize that the existence of a bird of this 
type might depend so entirely on an abundant rodent food supply that, 
with the gradual disappearance of the large indigenous rodents, the 
owl must also have become extinct, leaving the caves to the small 



12 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

Tyto glaucops cajjable of subsisting" on introchiced rats and mice, 
and on the native bats, lizards and small birds. Beneath a ledge in 
one of the caves near St. Michel I found pellets of the small owl on 
the surface, and, at a depth of from eighteen inches to two feet, 
compactly moulded masses of extinct rodent bones, evidently parts 
of the pellets of the extinct bird which once used this same resting 
place. 

BROTOMYS VORATUS Miller 
Plate 2, fig. I 

Two imperfect skulls and 52 mandibles. These sjx'cimens represent 
all the caves worked in with the exception of the deep cave near the 
Atalaye plantation. 

The skulls essentially agree with the type, from the Dominican 
Republic. The mandibles, when com|)ared with specimens of Boromys 
offcla and B. torrci collected in Cuba by William Palmer in 191 7 
show no striking peculiarities. In both species of Boromys, however, 
the masseter ridge on the outer side of the mandible is so developed 
that, in the region beneath nio, its upper surface projects almost at a 
right angle to the outer surface of the mandilile above it, while its 
extreme edge in some specimens is slightly turned upward. In 
Brotoinys the upper surface of the ridge slopes obliquely downward 
and the margin is not upturned. 

The three genera Brotoinys, the Cuban Boromys, and the Porto 
Rican Hctcropsomys are at once distinguishable from the other native 
Antillean rodents by their relatively low crowned, long rooted, 
subterete cheekteeth. All three are intimately related and it may 
eventually be found expedient to unite them under one name. For 
the present, however, it seems preferable to regard them as distinct 
from each other. The additional material now at hand makes it 
possible to define their differences as follows: 

Posterior termination of incisor root visible behind anterior base of 
zygoma when skull is viewed from below ; antorbital foramen rela- 
tively small, its height much less than length of toothrow Hetcropsomys. 

Posterior termination of incisor root not visible behind anterior base 
of zygoma when skull is viewed from below ; antorbital foramen 
relatively large, its height nearly equal to length of toothrow. 

A deep neural channel on floor of antorbital foramen ; posterior 

termination of incisor root marked by an obvious swelling. . . .Boromys. 
No definite neural channel on floor of antorbital foramen ; pos- 
terior termination of incisor root not marked by an obvious 
swelling Broiomys. 



NO. 9 MAMMALS FROM CAVES IN HAITI — MILLER I3 

BROTOMYS (?) CONTRACTUS sp. nov. 
Plate 2, fig. 2 

Type. — Anterior portion of skull, lacking zygomata, nasals and 
teeth, No. 253100, U. S. Nat. Mus. Collected in small cave near 
St. Michel, Haiti, March, 1925, by Gerrit S. Miller, Jr. 

Characters. — Resembling Brofomys voratus, but size slightly less, 
rostrum relatively shorter, interorbital region narrower in proportion 
to f rontopalatal depth and more arched transversely ; teeth broader 
than in Brofomys %'oratus, and palate noticeably constricted, its inter- 
alveolar width at middle conspicuously less than transverse diameter 
of the adjoining alveoli. 

Skull. — While reseml)ling in a general way that of Brofomys 
vorafus the skull of B. ( ?) confracfus. even in the imperfect condi- 
tion of the only known specimen, shows well marked differential 
characters. Most conspicuous among these is the narrowness of the 
bony palate as compared with the very wide alveoli of the anterior 
cheekteeth. In three specimens of B. vorafus (the type from the 
Dominican Republic and two from Haiti) the w^dth of the palate 
between the alveoli of the second cheekteeth is 2.55, 3.0 and 3.0. 
respectively, and the width of the first alveolus is 2.25, 2.25 and 2.30. 
In the type of 5. (?) confracfus the width of the palate at the same 
level is only 1.65, while that of the first alveolus is 3.60. The narrowing 
of the skull shown by the palate is also evident when the interor- 
bital breadth is compared with the fronto-palatal depth. In the type 
of Brofomys ( ?) confracfus the ratio of this breadth (15.6) to depth 
(13.0) is only 83.3, while in the three specimens of B. vorafus it is 
92.5, 90.0 and 92.6. The greater transverse convexity of the interor- 
bital roof is a character which cannot be expressed by measurements ; 
it is immediately obvious when specimens are compared in posterior 
view. Because of the imperfect condition of the skull a comparison 
of the length of the rostrum with anything but the length of the 
palate is difficult; hence the apparent shortening of the rostrum may 
be due in part to an actual lengthening of the palate to accommodate 
the enlarged teeth. In Brofomys ( ?) confracfus the length of the 
palate (9.4) measured from posterior border to level of anterior 
margin of alveolus of pm'^ is essentially equal to the distance fron] 
the latter level to alveolus of incisor (9.8) ; in B. ( ?) confracfus it is 
barely more than the distance from alveolar level to front of incisive 
foramina (that is, about 5 mm. less than the distance to alveolus of 
incisor). The alveolar length of the toothrow in the type oi B. (?) 
confracfus cannot be exactly measured (the alveolus of 7;:^ is entirely 



14 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

missing on one side and is incomplete on the other) but it must have 
been essentially equal to the diastema ( 10.8 mm.). In the three skulls 
of B. voratus it is 9.8, lo.o and 9.6, while the diastema in the same 
specimens is 13.6, 12.6 and 12.8, respectively. 

Sf^ccimciis cxauiiiicd. — One. the type. 

Remarks. — The disproportion 1)etwcen the alveoli and palate in 
this species as compared with Brotouiys voratus is so great as to 
suggest that, when more comjjletelv known, the animal will prove 
to represent a distinct genus. In all of the other related members 
of the group from the large Hctcropsouiys (and Hotiiof^soiiiys if 
distinct) of Porto Rico to the small Boroinys torrei of Cuba the 
proportionate width of palate and alveoli does not greatly vary ; 
the palate, at the iw^ level is always at least equal to the width 
of the largest alveolus. The narrowing of the palate to less than 
half the width of this alveolus in B. ( ?) contractus may therefore 
easily be a character of more than s]>ecific weight. 

ISOLOBODON LEVIR (Miller) 

Plate _'. Figs. 3, 3a 

1922 Isolobodon portoricensls Miller, Smithsonian Misc. Coll., Vol. 74. No. 3. 

p. 3. October 16, 1922. 
1922 Ithydontia levir Miller, Smithsonian Alisc. Coll., Vol. 74, No. 3, p. 5. 

October 16, 1922. 

Thirty palates and fragmentary skidls, more than 600 mandibles. 

This is the most abundantly represented of the vertebrates found 
in the bone bearing deposits. Its flesh seems to have been the chief 
article of food of the giant barn owl, Tyto ostolaga: many of the 
skulls and jaws were found in masses of bones which had the 
structure characteristic of owl pellets. 

The original collection from the large cave near St. Michel included 
two isolated upper premolars of Isolobodon. Wrongly determining 
them as lower teeth I made these specimens the basis of a new genus 
and species, Ithydontia levir, selecting as type what I supposed to be 
" a right mandibular tooth, probably pnu or n^." but actually, as the 
rich material now at hand clearly shows, pni* left. So far as the 
generic name Ithydontia is concerned there can be no doubt — it is a 
synonym of Isolobodon. But the proper disposition of the specific 
name is less easily determined. For the present it seems necessary 
to retain Isolobodon levir as the designation of the Haitian member 
of the genus. Although the absence of good skulls from the St. Michel 
series makes a satisfactory comparison with Isolobodon portoriccnsis 



NO. 9 MAMMALS FROM CAVES IN HAITI MILLER 1 5 

impossible, the .smaller size of the Haitian specimens is so constant as 
compared with material from Porto Rico and the Virgin Islands that 
the existence of two members of the genus appears to be established. 
The circumstance must not be overlooked that the Haitian food refuse 
was accumulated by owls, while that formed elsewhere was chiefly 
if not entirely deposited by men. Tt is possible therefore that the 
difference in size may be partly due to selection of the rodents used 
as food — the owls tending to capture smaller, more easily devoured 
individuals, the men preferring the larger ones. That the owls were 
able to eat animals as large as the largest Porto Rican Isolohodon is 
shown by the frequent presence in the deposits of Aphcctrciis jaws of 
equally large size. Whatever bearing the possibility of selection may 
have, the facts are as follows : 

Among more than 600 Haitian mandibles the eight largest have 
toothrows of the following lengths, 16.2, 16.2, 16.2, 16.4, 16.6, 17.0, 
17.2 and 17.2 mm., while the extremes of Anthony's measurements 
of individuals selected from a series of 200 Porto Rican specimens are 
17.6 and 19.2 mm. The three longest maxillary toothrov/s among the 
Haitian specimens selected for large size are 16.2, 16.2 and 17.0 mm. ; 
Anthony gives 17.2 to 19.3 mm. as the range of variation among 
adults in his series of 17 skulls. The interorbital breadth can be 
measured accurately or approximately in seven of the Haitian skulls. 
It ranges from 15 mm. to about 18 mm. ; Anthony's extremes are 
19.8 and 23.5 mm. in six skulls from Porto Rico. In two Haitian 
specimens the length of the frontal bone along the median suture is 
18.6 mm. and 20.0 mm. ; the extremes of eight from Porto Rico 
are given as 22 mm. and 30 mm., with only three specimens less than 
24.5 mm. The breadth of rostrum at premaxillary suture does not 
exceed 11 mm. in any of 15 Haitian specimens (some of them ob- 
viously immature), while in seven from Porto Rico it ranges from 
13 mm. to 14.5 mm. Under these circumstances it seems necessary 
to recognize the Haitian Isolohodon as a distinct form. 

The status of the Isolohodon whose bones have been found in 
kitchen middens in the Dominican Repulilic is a matter of special 
interest now that it becomes impossible to regard the Haitian member 
of the genus as identical with 7. portoricensis. I once said that there 
appears to be no way to distinguish between Dominican, Porto Rican 
and Virgin Island specimens ; ' and after going over the ground again 
in the present connection I am of the same opinion. A palate from 
San Pedro de Macoris, Dominican Republic, is broken in such a 



' Proc. U. S. Nat. Mus., Vol. 54, p. 508, October 15, 1918. 



l6 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

manner that the toothrow cannot be measured, but the alveolar length 
must have been at least i8 mm. ; enough of the base of the rostrum is 
preserved to show that the breadth at premaxillary suture was more 
than 13 mm. In three mandibles from the same locality the toothrow 
measures 17.6, 18.6 and 18.6 in contrast to the maximum of 17.2 for 
the entire series of over 600 jaws from the Haitian caves. Of two 
mandibles collected by Gabb at San Lorenzo Bay one has a toothrow 
18.8 mm. in length, while in the other, an olwiously younger individual, 
it is 16.8, only a little below the maximum for the Haitian specimens. 

APHJETREUS MONTANUS Miller 
Plate 2, figs. 4, 4a, 4b 

Seventeen imperfect skulls and palates, 208 jaws. 

In both groups of caves the remains of this animal were common, 
the frequency of their occurrence coming next after that of Isolobodon 
levir. 

The material at hand makes it possible to define the genus more 
completely than I was able to do in the original paper. It is now 
evident that the genera Aphcctrcus, Isolobodon and Plagiodontia form 
a rather compact group, the members of which are more nearly related 
to each other than any one of them is to Capromys and its allies. In 
all three the enamel pattern of the upper molars is tetramerous ; in 
Plagiodontia the upper premolar has reached the same stage of simplifi- 
cation, but in Aphcctrcus and Isolobodon this tooth retains a small 
fifth element. The maxillary teeth of Capromys and Gcocaproiiiys are 
all pentamerous. In the Isolobodon group the direction of the inner 
reentrant fold is diagonally forward in the upper teeth, backward in 
the lower teeth ; the reverse is the case in Capromys. The general 
structiu'e of the crowns in the Capromys grou]) parallels that which 
has been developed by the voles ; this is not true with regard to 
Isolobodon and its allies. The characters of the three genera may be 
tabulated as follows : 

Curve of upper incisor short, the root of the tooth lying at anterior 
margin of zygomatic process of maxillary ; lower incisor terminating 
beneath nn ; pm* with one outer reentrant angle, its enamel pattern 
exactly similar to that of the molars ; reentrant folds in upper teeth 
very oblique, their slant 45° or less as referred to corresponding 
alveolar line ; reentrant folds on inner side of the lower teeth extend- 
ing less than halfway across crowns; frontal sinus sufficiently inflated 
to produce an obvious swelling over anterior zygomatic root, to en- 
croach on area of antorbital foramen, and to a less degree on that of 
orbit ; posterior margin of zygomatic process of maxillary lying about 
in line with anterior alveolar border Plagiodontia. 



NO. 9 MAMMALS FROM CAVES IN HAITI MILLER 17 

Curve of upper incisor long, the root of the tooth lying in antorbital 
foramen; lower incisor terminating beneath m-.,; pm* with two outer 
reentrant angles, its enamel pattern obviously different from that of 
the molars ; reentrant folds in upper teeth not very oblique, their slant 
more than 45° as referred to corresponding alveolar line ; reentrant 
folds on inner side of lower teeth extending more than halfway across 
crowns: frontal sinus not sufficiently inflated to produce an obvious 
swelling over anterior zygomatic root or to encroach on area of ant- 
orbital foramen or of orbit ; posterior margin of zygomatic process 
of maxillary lying at or behind level of middle of alveolus of pm\ 
Opposed inner and outer reentrant angles of all teeth remaining 
distinct throughout life, the enamel pattern of each tooth 
entire ; crowns and alveoli of both upper and lower molars 

nearly as long as wide Isolobodon. 

Opposed inner and outer reentrant angles of all teeth becoming 
confluent in adults, the enamel pattern of each tooth then di- 
vided into two sections ; crowns and alveoli of both upper and 
lower molars conspicuously wider than long iplnrirciis. 

The series of mandil:)les includes about 30 specimens in which the 
breaking through of the opposed enamel folds has not yet taken place. 
Unfortunately there are no sets of upper teeth representing the same 
stage. In these immature individuals the enamel pattern of the mandib- 
ular teeth contains exactly the same elements that are present in the 
corresponding teeth of Isolobodon. The characteristic peculiarities of 
crown outline are, however, evident at a very early stage, and, though 
less pronounced than in the adults, they are sufificient to be diagnostic. 
In harmony with the shorter tooth crowns of Apluctrcus the enamel 
folds are narrow as compared with those of Isolobodon, and the re- 
entrants are more completely filled with cement. The crowns conse- 
quently tend to have a solid, squarish aspect, while in Isolobodon they 
are oblong and always with conspicuous angular emarginations. From 
the mandibular teeth of Plagiodontia those of ApJuctrcns are readily 
distinguished by the less oblique direction of all the enamel folds, and 
by the greater length of the outer reentrant, which fold invariably 
extends more than halfway across the crown, while in Plagiodontia 
it never reaches the middle of the crown. 

The maxillary teeth have not hitherto been known. Like the man- 
dibular teeth they contain the same elements that are present in 
Isolobodon, but these elements are compressed in the axis of the 
toothrow, and the opposed reentrant folds are confluent in adults, thus 
splitting the enamel pattern into two sections. The region of breaking 
through in the maxillary teeth is clearly indicated by irregularities in 
the enamel outline ; hence it seems probable that in young individuals 
it will be found that the pattern is not split. 



l8 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

Two toothless mandibles, not improbably pertaining to one indi- 
vidual, dug from the small available area of original floor material in 
the caved-in chamber near St. Michel, are unique, among the octodont 
rodents which I have examined, in the presence of a well developed 
fifth alveolus behind the normal fourth (pi. 2, fig. 46). 

PLAGIODONTIA ^DIUM F. Cuvier 

Seven mandibles (five from the group of caves near St. Michel, 
the others from the crooked cave near I'Atalaye) are referable to the 
species represented by the large specimen from San Pedro de Macoris, 
Dominican Republic, which I have identified (Proc. U. S. Nat. Mus.. 
Vol. yz. Art. 16, pp. 5-6, September 30, 1927) as an individual of 
the species originally described by F. Cuvier. Only one of the Haitian 
specimens is fully adult, and in this the coronoid and angular regions 
are broken ofif and all the teeth have been lost. Its size must have been 
almost exactly the same as that of the Macoris jaw. In each the length 
of the symphysis menti is 27.6 mm. and the distance from the posterior 
angle of the symphysis to anterior margin of alveolus of pm^ is 20.4. 
Among 13 jaws of the recently described Dominican Plagiodontia 
hylccuui Miller the maxima for these two measurements are only 25.4 
and 19.0, while the usual dimensions in adults are decidedly less, about 
24 and 17. The length of the toothrow in the adult Haitian P. (rdium, 
23.4, is only 0.6 mm. less than that in the Macoris specimen ; the 
maximum in the series of P. hylceuni is 20.6. In two of the younger 
Haitian individuals, both of them broken off immediately behind the 
toothrow, the second molar is not yet fully in place. They are, how- 
ever, distinctly larger and more robust than in two jaws of immature 
Dominican P. hyhrmu, one with m^ worn fiat but j;;^ not in place, the 
other with all the crowns worn flat. In the five Haitian specimens 
with teeth the enamel pattern presents the characters which distinguish 
Plagiodontia cedium from P. hylcciim (see Miller, Proc. U. S. Nat. 
Mus., Vol. y2, art. 16, p. 4, and pi. i, figs, ic and 2, September 30, 
1927). 

PLAGIODONTIA SPELiEUM sp. nov. 

Type. — Right mandible of young adult. No. 253160, U. S. Nat. 
Mus. Collected in the crooked cave near the Atalaye plantation, Haiti, 
March, 1925, by Gerrit S. Miller, Jr. 

Characters. — Resembling Plagiodontia liyhcitui Miller from eastern 
Dominican Republic but noticeably smaller; length of mandible mea- 
sured from articular process probably not much exceeding 40 muL 



NO. 9 MAMMALS FROM CAVES IN HAITI MILLER I9 

instead of ranginj^ from about 48 to 54 mm. ; mandibular toothrow 
usually less than 18 mm. instead of ranging from about 18.5 to 
20.5 mm. Portion of mandible in front of cheekteeth relatively shorter 
and more abruptly curved than in P. hylcpum. 

Measurements. — From five jaws which may be regarded as adult 
I am able to obtain the following measurements : length of mandible 
from articular process, 39.6, 39 ±, — , — , — , length of symphysis, 
18.0, 18 ±, 17 ±. 17.6, — ; diastema, 9.0, 9.4, g±, 8.8, 9.2; depth 
from alveolar margin to lowermost point of symphysis, 1 1.2, 11 .2, 1 1.2, 
10.8, 11.6; mandibular toothrow (alveoli), 16.2, 16.0, 15.8, 16.0, 15.6; 
transverse diameter of iiii (grinding surface), 4.5, 4.5, 4.5, 4.2, 4.4. 
The same measurements in a mandible of F. hylcemn which appears 
to be of exactly corresponding age (No. 239886) : length from articu- 
lar process, 48 ; symphysis, 21.6 ; diastema, 1 1.4 ; depth 13.0 ; toothrow, 
18.6; width of nil, 5-3- 

Specimens examined. — Fifteen mandibles, all imperfect. Four of 
these came from the group of caves near St. Michel, the others were 
found in the crooked cave near the Atalaye plantation. 

Remarks. — The small Plagiodontia from the St. Michel caves differs 
conspicuously from the associated large P. cediiwi in size and in the 
longitudinally compressed cheekteeth. Its affinities are obviously with 
P. hylceum of the Samana Bay region, the only member of the genus 
known to be now living. At first sight the jaws of Plagiodontia 
spelceum might be mistaken for immature specimens of F. hylceum, 
but when comparison is made lietween individuals in corresponding 
stages of development (as indicated in immature individuals by the 
eruption of the second and third molars, and in young adults by the 
gradual disappearing of porousness and surface wrinkling of the bone 
on the lower side of the jaw beneath the roots of these teeth) the 
differences between the two species become obvious. 

HEXOLOBODON gen. nov. 

Plate 3, tigs. I, la, lb 

Type. — Hcxolobodon phcnax sp. nov. 

Characters. — So far as known most like Geocapromys, but differing 
as follows : cheekteeth with roots becoming closed at or soon after 
the stage when the crowns are worn flat ; root of lower incisor passing 
beneath root of m-^ and terminating, in fully adult individuals, on outer 
side of toothrow beneath the floor of the groove which separates the 
alveolus of 7W3 from the base of the coronoid process; pm^ (pi. 3, 
fig. la) with only two reentrant angles on inner side (as in Capromys) ; 



20 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 51 

all of the maxillary teeth with two about equally developed reentrant 
angles on each side, these imparting to the crowns an evenly six-lobed 
structure (pi. 3, fig. i). 

Remarks. — In the general structure of the palate and the relation- 
ship of the incisor roots to those of the premolars this genus is prac- 
tically identical with Gcocapromys. The roots of the premolars come 
close together in the median line, where they are overgrown by the 
maxillary exactly as in Gcocapromys. The roots of the premolars 
with their covering of bone fill up the lower part of the narial channel 
in the region between the incisor roots (pi. 3. fig, i^). A broken 
palate without teeth could be distinguished by this character alone 
from a similar fragment of a Caproiiiys or Plagiodontia skull, in both 
of which the anterior part of the narial channel is widely open between 
the roots of the premolars (pi. 3, fig. 2), but might be confused with 
a similar fragment pertaining to a member of the genera Gcocapromys, 
Isolohodon, or Apluetrcus. 

In Gcocapromys and Capromys (pi. 3, fig. 2) the roots of all four 
cheekteeth, when exposed by cutting or breaking away their bony 
covering, are seen to l)e about evenly spaced in the toothrow — at most 
the septum between the roots of pm* and m^ is slightly thicker than 
the septa between the molars. In Hc.volobodon, on the contrary (pi. 3, 
fig. lb), the root of the premolar is thrown conspicuously forward 
away from that of the first molar. 

The less si>ecialized condition of the roots of the cheekteeth and 
the extension of the lower incisor root to the outer side of the 
mandibular toothrow are characters which, like the enamel jjattern of 
the upper teeth, sharply difi^erentiate this genus from its Antillean 
relatives Capromys, Gcocapromys. Plagiodontia, Aphcctrctts, and 
Isolohodo}}. 

HEXOLOBODON PHENAX sp. nov. 

Plate 3, figs. I, la, ib 

Type. — Palate with complete dentition of immature individual {m^ 
with only anterior half of crown worn flat). No. 2531 18. U. S. Nat. 
Mus. Collected in the small cave near St. Michel, March, 1925, by 
Gerrit S. Miller, Jr. 

Characters. — An animal about the size of Capromys piloridcs, 
but skull i)robably ditfering from that of all species of Capromys and 
Gcocapromys in shorter rostrum and generally more robust form. 
With regard to features which are not obviously generic, such exact 
comparisons with Capromys piloridcs as the fragmentary remains of 



NO. 9 MAMMAI,S FROM CAVES IN HAITI MILLER 21 

the extinct animal will permit, are as follows : palate in region between 
pni* and maxillo-premaxillary suture much smaller relatively to grind- 
ing area of toothrow ( about 10x14 mm. as compared with 13x18 mm. 
in a specimen of C. piloridcs with grinding area of toothrow of essen- 
tially the same length and breadth as that of the type), its upward 
slope more abrupt ; no obvious pit for attachment of the maxillo-naso- 
labialis muscle in region between puii and incisive foramen (these 
pits are visible in all the living species of Capromys and Geocapromys; 
they are not developed in Isolohodon, Aphcctreus or Flagiodontia) ; 
posterior emargination of palate extending forward slightly beyond 
level of posterior border of in- instead of about to middle of m^ ; 
narrow inferior maxillary zygomatic root, its width through middle 
of specialized muscle-insertion area considerably less than width of 
grinding surface of molars instead of distinctly greater than width of 
this surface. The upper toothrows are more convergent than in 
Capromys piloridcs, so that the bony palate becomes reduced anteriorly 
to a width only about one-fifth that of the adjoining alveolus or of its 
own width posteriorly. In C. piloridcs the anterior width of palate is 
considerably more than half that of alveolus and almost exactly half 
of its own posterior width. Posterior emargination of palate extend- 
ing slightly beyond level of septum between alveoli of m^ and ur. All 
of the mandibles are broken immediately behind the toothrows. In 
the portion which remains there are several obvious peculiarities as 
compared with the corresponding region in Capromys piloridcs. The 
diastema is short and more abruptly concave when viewed from the 
side. The symphysis is conspicuously shorter than in C. piloridcs and 
its long axis is set at a higher angle to the plane of the grinding 
surface of the molars ; about 50° instead of about 35°. The anterior 
portion of the ridge which extends forward along the outer side of the 
mandible from the angular process is heavier and more evenly rounded 
than in the Cuban animal. The enamel pattern of the mandibular teeth 
appears to be not positively distinguishable from that of Capromys 
piloridcs. 

Measurements. — Type : distance from posterior surface of m^ to 
anterior border of maxillary directly in front of toothrow, 30.0 
(35.0) ; ^ distance from posterior margin of incisive foramen to poste- 
rior margin of palate, 24.6 (26.2) ; distance from alveolus of pm* to 
anterior edge of maxillary, 9.4 (13.2) ; width of bony palate through 



^ Measurements in parenthesis are those of a similarly broken palate of a 
slightly older individual of Capromys pUorldes from Sierra La Guira, Pinar del 
Rio, Cuba (No. 253232, U. S. Nat. Mus.). 



22 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

anterior edge of posterior emargination, 5.6 (8.2) ; least width of 
palate between toothrows, 1.2 (4.0) ; maxillary toothrow (alveoli) 22.0 
(22.4) ; alveolar width of pin^, 5.8 (5.2) ; height of ni^ from grinding 
surface to root, 15.0 (14.0). Mandible of an individual with teeth 
in same stage of wear as those of type: distance in alveolar line from 
posterior margin of m^ to anterior margin of incisor, 36.0 ; distance 
from tip of incisor to posterior edge of grinding surface of m-i, 38.0 ; 
diastema, lo.o; distance from tip of incisor to anterior margin of 
crown of pmt, 15.8; depth from inner margin of alveolus of piih to 
l)Osterior point of symphysis, 14.4; length of symphysis, 22.4; length 
of toothrow, grinding surface, 22.2, alveoli, 24.0; alveolar width of 
pMi, 5.8. Mandible of an individual with crown of m^ entirely worn 
flat : distance in alveolar line from posterior margin of m-i to anterior 
margin of incisor, 37 ± (46.6) ;^ diastema, ii± (18.8) ; depth from 
inner margin of alveolus of ptih to posterior point of symphysis, 17 ± 
( 19.0) ; length of symphysis, 23 ± (23.0) ; length of toothrow, grind- 
ing surface, 24.2 (22.0) ; alveoli, 25.0 (22.4) ; alveolar width of puii, 

54 (5-0). 

Specimens examined. — One palate, six mandibles and four isolated 
cheekteeth. A mandible and two of the isolated teeth were found in 
the caves near I'Atalaye, the rest of the material came from the large 
and small caves near St. Michel. 

QUEMISIA gen. nov. 

Plate 4, figs. 2, 2a 

Type. — Queinisia gravis sp. nov. 

Characters. — Size and general features probably as in the Porto 
Rican Elasmodontomys. Enamel pattern of mandibular cheekteeth 
(pi. 4, fig. 2a) like that of Elasmodontomys (pi. 4, fig. la) but reentrant 
folds less transverse to the axis of the toothrow, the axis of the folds 
slanting forward at an angle of only 21° instead of about 50°. 
Mandibular symphysis extending backward beyond level of middle 
of mi instead of barely to middle of pm^ ; shaft of lower incisor not 
extending behind symphysis, its base lying beneath anterior half of 
Wi (in Elasmodontomys the shaft of the incisor extends far beyond 
the symphysis to terminate beneath middle of W2) ; shaft of femur 
more flattened than in Elasmodontomys. 



^Measurements in parenthesis are those of an adult Caproinys pilorides (No. 
143150). 



NO. 9 MAMMALS FROM CAVES IN HAITI MII.LKR 23 

Remarks. — The genus Quemisia is a member of the group which is 
represented by Elasmodontoinys in Porto Rico and Ainhlyrhisa in 
Anguilla. The cheekteeth in all three of these genera are very hypso- 
dont but not ever-growing. The enamel pattern is pentamerous with 
the inner reentrant fold of the upper teeth (in Amblyrhisa and 
Elasmodontoinys, at least) and the outer fold of the lower teeth 
passing behind the posterior outer reentrant. All of the reentrant 
folds penetrate nearly or quite across to the opposite side of the crown, 
thus producing a grinding surface which consists of a series of essen- 
tially parallel transverse enamel ridges. 

The most striking known peculiarities of Quemisia are the long 
mandibular symphysis, short lower incisor, and the very unusual for- 
wardly-directed enamel folds in the lower teeth. I have chosen the 
name because of my belief that the animal is probably the " Quemi " 
of Oviedo (Hist. Gen. et Nat. de las Indias, Madrid, 1851, p. 389). 

QUEMISIA GRAVIS sp. nov. 
Plate 4, figs. 2, 2a 

Type. — Mandible of immature individual ( m-, with crown not yet 
in place). No. 253175. U. S. Nat. Mus. Collected in the crooked cave 
near the Atalaye plantation, March, 1925, by Gerrit S. Miller, Jr. 

Characters. — As compared with a mandible of Elasmodontomys 
obliquus in corresponding stage of tooth growth the type specimen 
of Quemisia gravis shows many peculiarities in addition to those which 
have already been described. The depth of the horizontal ramus at 
middle of m^ is greater in proportion to the length of the toothrow 
(21.5:33 instead of 18:34); the maximum width through the 
symphysis is greater (17.5 instead of ii ) a difference occasioned partly 
but not wholly by the more posterior point of termination of the 
symphysis in the Haitian animal. The anterior base of the angular 
process is laterally compressed in Quemisia, so that it forms about 
one-third of the transverse diameter of the mandible; in Elasmodon- 
tomys it is so thick that it forms considerably more than half of the 
entire transverse diameter. The roots of the third and fourth cheek- 
teeth extend down into this thickened area in Elasmodontomys. In 
Quemisia the roots of the three molars form a broadly curved ridge 
extending backward and upward from the symphysis and separated 
from the base of the angular process by a shallow groove; this ridge 
has, at first sight, something the appearance of the ridge which marks 
the course of the incisor root in Elasmodontomys. 



24 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

The cheekteeth are oj^en at the base, as in Elasmodoutoinys of the 
same age ; whether or not they eventually become closed as in adult 
Elasmodontoiuys cannot now be determined. The enamel pattern is 
fundamentally the same as in Elasiiiodoiifoiiiys, that is, a pentamerous 
pattern in which all the reentrant folds have been extended nearly or 
quite across the crown ( the outer fold passing behind the second inner 
fold). The posterior limb of each fold has been thickened to form a 
conspicuous enamel plate and the anterior limb of each fold except 
the first has been reduced to the vanishing stage. As compared with 
that of the Porto Rican animal the pattern in Queuiis'ia shows a 
mixture of excessive peculiarity and less high specialization. The 
forward turning of the enamel folds so that the anterior portion of 
each fold is approximately parallel with the main axis of the toothrow 
is a specialization of high degree and very peculiar kind. In 
lilasuiodoutomys there is an indication of this tendency at the front 
of the premolar, but the direction of the folds in the molars is normal 
and not essentially different from that seen in Plagiodontia, Isolobodon 
or Aphcutreus. On the other hand the process of plate specialization 
has not progressed so far in Qiiciiiisia as it has in Elasiiiodoiitomys. 
While the external reentrant fold has extended completely across the 
crown in all three of the used cheekteeth neither of the two internal 
folds has cjuite reached the enamel of the opposite side in pui^, and 
only the first has penetrated so deeply in iiii and uio. In each of the 
molars there is, therefore, one incomplete enamel plate, the second, 
while in the premolar there are two, the first and second. In 
Elasiiiodontoiiiys all the folds have crossed the crown in all the teeth, 
and there are, consequently, no incomplete plates. The peculiar twist- 
ing of the enamel pattern almost into the axis of the toothrow in 
Oucinisia throws the anterior loop of each tooth over on to the inner 
side of the crown out of contact with the tooth in front of it. The 
free face of each of these loops carries a fully developed enamel 
wall. In Elasmodontomys such an enamel wall occurs on the first loop 
of the premolar only. 

A fragment of incisor (apparently an upper tooth) 19 mm. in length 
has a width of 5 mm. and an antero-posterior diameter of 4.2 mm. at 
level immediately proximal to the terminal worn area. The anterior 
face is longitudinally fluted by six obscurely developed ridges and the 
faint intervening concavities. 

A broken femur which I refer without much doubt to this species 
differs from the corresponding bone in Elasmodoutoinys obliquus in 
the conspicuous flattening of its shaft. The greatest and least diameters 



I 



NO. 9 MAMMALS FROM CAVES IN HAITI MILLER 25 

of the shaft in its narrowest region are 12.2 and 8.2, while in one 
specimen from Porto Rico they are 10.8 and 8.8, and in another 13.0 
and 9.8. 

Specimens cxauiiued. — ]\Iandil)]e and piece of an incisor from the 
crooked cave near the Atalaye plantation ; hroken femur from the 
small cave of the same group. 

XENARTHRA 

The occurrence of ground sloths in Hispaniola was not known he- 
fore the discovery of a few hones in the St. Michel caves hy Mr. Brown 
and Mr. Burhank. On the basis of this scanty material — four vertebrae, 
three of them imi:)erfect, a piece of a limb bone of a young animal, 
and a fragment of a rib — I was unable to refer the species to 
any genus, and. at Doctor Matthew's suggestion, 1 recorded it ' as 
Megalocnus ? sp. ? 

On visiting the caves myself I secured teeth and a femur resembling 
the corresponding parts of the Porto Rican Acratociius and also a 
calcaneum so unlike that of Acratociius as to suggest the existence 
of two sloths differing generically from each other. The material 
collected by Mr. Poole now makes the definite separation of these 
animals possible. One is slender limbed, resembling Acratociius in 
size and general features ; the other is more heavy, its general build 
probably somewhat as in NotJirotJierium sJiastense. Its bulk, however, 
though considerably exceeding that of Acratocnus, is not likely to have 
been much more than one-fourth that of the Californian animal. 

That one or both of these sloths continued to exist on the island 
until after the advent of man I have no doul)t. The facts which have 
led me to this conclusion are as follows: (a) In the two caves near 
St. Michel most of the sloth remains were found within two feet of 
the surface ; and human l)ones and pottery occurred to the same depth 
without any indication that they had been dug in. (b) Near the en- 
trance to the smaller of the two main caves bones of ground sloths 
(certainly two and perhaps more individuals) were inextricably mixed 
with bones of man (adult and infant) and domestic pig. The remains 
were scattered among the small fragments of limestone which made 
up the greater part of the floor material, and I was unable to deter- 
mine any definite level-relationship among them, (c) Near the en- 
trance to the large cave I unearthed with a trowel, in fine, soft, undis- 
turbed material at the bottom of a trench two feet deeji, the femur 



' Smithsonian Misc. Coll., Vol. 74, No. 3, p. 6, October 16, 1922. 



26 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

of a ground sloth, and. about 18 inches from it, a fragment of coarse 
dark pottery. There was no evidence of previous digging that I could 
discover ; and the bone and pottery had every appearance of having 
been deposited on the former surface of the cave floor and subse- 
(juently covered by the gradual accumulation of detritus, (d) Both 
of these caves are situated on the side of a high ridge where the 
material composing their floors is entirely removed from the action 
of streams, (e) In general the ground sloth bones were, associated 
with the human remains in exactly the same manner as the bones of 
Isolohodon and Plagiodontia, rodents which are positively known to 
have been contemporary with man. 

ACRATOCNUS (?) COMES sp. nov. 
Plate 5, fig. 2; plate 6, fig. 2; plate 8, fig. r ; plate lo, fig. i 

Type. — Right femur (lacking distal extremity) of adult, No. 
253178, U. S. Nat. Mus. Collected in large cave near St. Michel, 
Haiti, March, 1925, by Gerrit S. Miller, Jr. 

Characters. — A small ground sloth agreeing in general size with the 
Porto Rican Acratocnus odonfrigonus Anthon} ; its weight probably 
not exceeding 50 pounds. Femur resembling that of the Porto Rican 
sloth, and, like it, with a well developed lesser trochanter and without 
noticeable antero-posterior compression of the shaft, but modified 
for more directly perpendicular weight-bearing. 

Femur. — The femur differs from the corresponding bone of Acra- 
tucnus odontrigoniis in at least two features which are important 
enough to indicate specific or, possibly, generic distinctness, (i) The 
intertrochanteric ridge is similar in position and development to the 
corresponding structure in A. odontrigoniis, but it is supplemented 
by a large and conspicuous tubercle situated at the middle of the 
shaft at a level slightly below that of the lesser trochanter. This 
tubercle, of which no obvious trace exists in the numerous Porto Rican 
femora with which I have compared the Haitian specimen, forms 
the culminating point of a general thickening of the bone which 
imparts to the upper fourth of the shaft, as viewed from the side, a 
strongly angular-convex profile very diff'erent from the flat or slightly 
concave profile of the same region in A. odonfrigonus (see pi. 6). 
(2) The neck is shorter than in Acratocnus odontrigonus and is less 
bent outward and forward from the axis of the upper half of the 
shaft; as a result, the head is set so as to diverge less noticeably 
from the general contour of the shaft. The differences in this respect 
between the Porto Rican and Haitian animals are of the same kind 



NO. 9 MAMMALS FROM CAVES IN HAITI MILLER 2'J 

as those which exist in greater degree between the femora of Cholospus 
and Bradypus. The less anterior directing of the neck in the Haitian 
femur is perhaps most readily made apparent by applying the proxi- 
mal extremity of the bone to a flat surface in such a way that it is 
supported by the tripod formed by the posterior surfaces of the head 
and the two trochanters. The shaft of the bone in Acratocnus ( ?) 
comes then takes a position essentially parallel with the flat surface. 
When the femur of A. odontrigonns is similarly placed the shaft rises 
above the flat surface at an angle ranging from about i8° to about 
23°. The same difference may be observed by tracing the direction 
of the low but usually evident ridge which crosses the neck from 
the head to the lesser trochanter. In Acratocnus odontrigonns this 
ridge extends so obliquely to the inner surface of the femur that its 
line, when continued downward, passes beyond the contour of the 
bone at a point situated near the mid portion of the head of the tro- 
chanter; in the Haitian specimen it passes out nearly 10 mm. farther 
down the shaft. The lesser inward bend of the neck is best appreciated 
by " sighting " down the anterior or posterior surface of the shaft of 
the bone ; it then becomes obvious that the head lies nearer to the 
main axis in the Haitian specimen than in any of those from Porto 
Rico. 

Remarks. — The femur on which this species is based resembles 
in all its general characters the corresponding bone of the Porto 
Rican ground sloths and of the Miocene South American Hapalops. 
The peculiarities which I have described as distinguishing it from the 
femur of Acratocnus odontrigonns separate it equally from the cor- 
responding bone of Hapalops, at least so far as can be determined 
from Scott's figures of three species {longiceps, pi. 32. elongatus. 
pi. 41, and ruetimeyeri, pi. 42). 

Other remains which I refer without much hesitation to Acratoc- 
nus ( ?) comes are as follows : (a) the proximal two-thirds of a right 
tibia (pi. 8, fig. i ) not certainly distinguishable from the corresponding 
part of the tibia of a Porto Rican ground sloth (No. 17711, Amer. 
Mus. Nat. Hist.) ; (b) an almost perfect atlas (pi. 10, fig. i) of the 
proper size to fit a skull of Acratocnus odontrigonus ; several canini- 
form teeth, both upper and lower, agreeing in a general way with 
those of the same animal; (c) foot bones and ungual phalanges 
resembling those of the Porto Rican species. 

On the basis of the femur and of the parts which appear to be 
almost certainly associated with it I do not now feel justified in separat- 
ing the small Haitian ground sloth more than specifically from Acratoc- 



28 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

iius odontrigonus. It would cause no surprise, however, if further 
material should indicate that the animals were generically distinct. 

The name comes alludes to the circumstance that the type specimen 
was found so closely associated with fragments of pottery as to lend 
strong support to the belief that the animal existed in Haiti as a 
contemporary of man. 

PAROCNUS gen. nov. 

Plate 7; plate 8, tig. _' ; ])late 9; plate 10, tigs. J. 3 

Type. — Parociius scnts sp. nov. 

Characters. — Femur dififering from that of Acrafocints in the 
absence of the lesser trochanter; in the conspicuous widening and 
flattening of the upper half of the shaft ; and in the more nearly 
vertical set of the head (as indicated by the line of the epiphyseal 
suture in an immature individual), a condition which appears to 
agree essentially with that present in N othr other ium as shown on plate 
12 of Stock's Gravigrade Cenozoic Edentates of Western North 
America. 

Remarks. — The genus Parocnus is readily distinguishable from 
AcratocHHS 1)y the structure of the femur alone. If I have correctly 
assembled the other parts which I believe to be associated with it 
there are many important differential characters. These parts are as 
follows: (a) a right humerus (pi. g), 200 mm. in greatest length, 
resembling that of NothrotJierium shastense as figured by Stock 
( Cenozoic Gravigrade Edentates of Western North America, pi. 8. 
fig. I, 1925) in general form but less heavily built, with relativel\ 
broader proximal extremity and without the entepicondylar foramen 
present in this sloth and in Acratocnus; (b) the proximal third of 
a left tibia (pi. 8, fig. 2) and an entire left fibula probably of the 
.same individual ; (c) a right astragalus (pi. 9, fig. 3) very different 
from that of Hapalops as figured by Scott (Rep. Princeton Exped. 
Patagonia, Pal., A'ol. 2, pi. t^t^, fig. 4) and Acratocnus as figured by 
.\nthony ( MeuL Amer. INIus. Nat. Hist., n. s., \o\. 2, pi. 73. fig. 7, 
1918) but resembling in a general way, particularly in its calcaneal 
aspect, the very much larger calcaneum of Mcgalonyx figured by 
Stock (p. 87, fig. 31, A, B, C, D) ; (d) three calcanea (2 left, 
I right) of a form (pi. 9, fig. 2) conspicuously different from that 
seen in Hapalops and Acratocnus but essentially similar in plantar 
and astragalar views to the calcaneum of Mylodon as figured by Stock 



NO. 9 MAMMALS FROM CAVES IN HAITI MILLER 2g 

(p. 175, fig. 96) ; (e) a fragment of an atlas much larger than the 
corresponding part in Acratocnus odontrigonns or O. ( ?) comes. The 
area of the superior articular process in this atlas is nearly four times 
as great as that of another specimen from the same cave (the large 
cave near St. Michel) which I refer without much hesitation to 0. ( ?) 
comes (pi. 10, fig. i) ; (f) several foot bones and ungual phalanges 
of more robust structure than any known in the Porto Rican Sloth. 

PAROCNUS SERUS sp. nov. 

Plate 7; plate 8, fig. 2; plate 9; plate 10, figs. 2, 3 

Type. — Right femur (lacking epiphyses) of immature individual, 
No. 253228, U. S. Nat. Mus. Collected in large cave near St. Michel. 
Haiti, January, 1928, by Arthur J. Poole. 

Characters. — An animal considerably larger and more heavily 
built than Acratocnus odontrigonns or A. ( ?) comes, its weight as 
roughly estimated by comparison of limb bones with those of pigs, 
probably 150 lbs. or more. 

Femur. — As compared with that of Acratocnus odontrigonns the 
femur of Parocnns serus (pi. 7) is immediately distinguishable by 
the absence of the lesser trochanter, as well as by its greater size 
and the much more noticeable antero-jwsterior flattening of the upper 
portion of the shaft. In a large femur of Acratocnus (No. 177 16. 
Amer. Mus. Nat. Hist.) the two diameters of the shaft at middle of 
its upper half, lateral and antero-posterior, are respectively, 26 mm. 
and 17 mm.; in the type of Parocnus tardus they are 38 mm. and 
14.5 mm. The ratio of antero-posterior to lateral diameters is there- 
fore about 65 in Acratocnus and only about 38 in Parocnus. At 
middle of shaft the discrepancy is slightly less : ratio of antero- 
posterior to lateral diameter about 61 in Acratocnus, about 45 in 
Parocnus. Below the middle of the shaft the diameters in the two 
femurs are essentially alike, with ratios of 58 and 59, a difference 
which is too slight to have any special significance. 

In addition to this striking peculiarity of general form the femur 
of Parocnus serus is further distinguished from that of the known 
species of Acratocnus by the absence of a lesser trochanter and the 
presence of a low ridge about 35 mm. in length extending obliquely 
downward and backward from the middle of the neck across the 
narrow inner aspect of the bone to its posterior margin ; by the more 
thickened gluteal ridge; and by the presence of a noticeable con- 



30 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

cavity on the posterior face of the shaft at the base of the great 
trochanter. 

Unfortunately no perfect skulls of ground sloths have yet been 
found in the Haitian caves. One specimen from the small cave near 
St. Michel includes the interorbital region and anterior part of the 
braincase. It is about the size of the corresponding part of the skull 
in a large Acratocnus odontrigonus, but is conspicuously different 
in form, owing to the absence of the deep postorbital constriction 
which is such a noticeable feature in the skull of Acratocnus. Whether 
this fragment pertains to a skull of Parocnus or of Acratocnus ( ?) 
conies is a question which cannot be answered. A fragment of a 
palate from the same cave appears to have come from a skull of 
much the same size. It indicates a palate twice as wide in proportion 
to the length of the toothrow as that of Acratocnus odontrigonus, 
and it further differs from the palate of the Porto Rican sloth in 
the presence of a median longitudinal ridge supplemented, on each 
side, by a shallow but well-defined longitudinal furrow. The toothrow 
in this individual was probably of almost exactly the same length 
as that of the Porto Rican specimen figured by Anthony on plate 69 
(fig. ic). 



I 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOL. 81, NO. 9, PL. 1 



a. - \ 




m^ 




^ 



1 







1 



^ 





^ 



(.\1I tigure.s natural size) 

1. XrsDphniitfs /^araiiiicnis Miller. Nos. 253062-233076, U. S. Nat. Mus. 

a. 2 skulls (the type at right) : b. 6 mandihles : c, three humeri ; d, 3 
femora ; c, innominate. 

2. ScsophonU-s hypomicrus Miller. Xos. 253077-253089, I'. S. Xat. Mus. 

Letters as in Hg. i. Type skull at right. 

3. Xcsnphpiitcs ::aiiiiinis Miller. Xos. 253090-253094, U. S. Nat. Mus. 

Letters as in hg. i. Type skull at left. 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOL. 81 , NO. 9, PL. 2 







3a 




4-< 



4i> 



(All figures natural size) 

1. Brotomys loratus Miller. Xn. j^T,(tgj. V. S. Xat. Mus. 

2. Brotomys ( ? ) contractus Miller. Type. 

3. Isolobodon Icvir (Miller). No. 2531 17, U. S. Nat. Mus. 
3a. Isolobodon Icvir Miller. No. 253102, U. S. Nat. Mus. 

4. .IphcctrcKs montanns Miller. No. 253133. U. S. Nat. Mus. 
4a. Apluctrcus montanus Miller. No. 253145, L'. S. Nat. Mus. 
4I). .If^hictrcus )nontaniis Miller. No. 253151, L'. S. Nat. Mus. 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOL. 81, 'NO. 9, PL. 3 



„WWJ«^. 



^^r 





a 



^ 





(All hgurcs natural size) 

I. Ilcxolobodou plu'iuix Milltr. Type specimen. Crowns of maxil- 
lary teeth. ^^ ^ ,, , , ^ 

la. Hexolobodon fhcmix Miller. No. 25312S. U. S. Nat. Mus. Crowns 
of mandibular teeth. . . 

il) Hevolobodon phcnax Miller. Type specimen, shownig alveolus ot 
left incisor, roots of maxillary teeth and mtervennig Hoor ot 
narial passage. tt c- \- . at 

^ Cohromxs pUorides Desmarest. No. 253^32, U. S. Nat. Mus. 
Palate broken away from rest of skull m the same manner as 
the tyne of Hexolobodon to show corresponding structures. 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOL. 81 , NO. 9, PL. 4 



^ 




N\'m^i«e"' 



\ 






'X.. 




s^ 




la 




ZCK 

( All figures natural size ) 

1. Hlasiiiodoiitoniys obliqiius Anthony. Immature, with third molar 

not yet above level of alveolar rim. Xo. 17137 h. .\mer. Mus. 
Xat.' Hist. 

2. Oiiciiiisia cjnn'is Miller. Type. Same stage of growth as hg. 1. 

In both specimens the alveolus of the incisor has been tapped 
at its base and a black thread pas^^ed through the tube. 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOL. 81, NO. 9, PL. 5 




(Both figures natural size) 

1. Right femur of Acratocnus odojilrif/onus .\ntliony, anterior aspect. 

No. 17711. Amer. Mus. Nat. Hist. 

2. Right femur of Acratncuus {'■!) comes Miller, anterior aspect, lype. 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOL. 81, NO. 9, PL. 6 




^i- 





( Rotb figures natural size) 

Right femur of .-!crafociius odontrigonus Antlmiiy, Duter 
aspect. No. i/Jii. Anier. AIus. Nat. Hist. 

Right femur of .livatocnus (?) comes Miller, outer 
aspect. Type. 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOL. 81, NO. 9, PL. 7 




( Natural size) 
Kis-Iit femur of rarornits scrus Miller, auterior aspect. Type. 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOL. 81 , NO. 9, PL. 8 





( Roth hiiures natural size ) 

1. Right til)ia (if . h-rati>cuiis (?) coiiuw. No. 253179, U. S. Nat. Mus 

2. Left tiljia of /'urocniis .wntx. No. J53230. U. S. Nat. Mus. 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOL. 81 , NO. 9, PL. 9 




(Both figures ^ natural size) 
I. Right humerus of Parocnus scrus Miller, anterior aspect. No. 233231. 

LJ. S. Nat. Mus. 
la. Rio-ht humerus of raroriius scrus Miller, outer aspect. No. 253231, 

U. S. Nat. Mus. 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOL. 81, NO. 9. PL. 10 







(All I'lgiires nrilural ^i^^■ ) 

Atlas (it . IcTiitdi litis ( ?) cuiiu-s MillcT, anterior aspect. 

L'. S. Xat. Mus. 
Left calcaneiiiii of Parnciius scnts ? (inter aspect. 

I'. S. Xat. Mus. 
Left calci.neimi of runiciiiis smis ? dorsal a.sjiect. 

L'. S. Nat. Mns. 
Ri<;ht astragalus of /'nnnitiis srnis ? outer asjjcct. 

'L'. S. Nat. Mns. 
Kitilit astragalus (if f'tiiuHUiis scnis '' inferior as|)ect. 

L. S. Xat. .\lus. 



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SMITHSONIAN MJSCELLANEOUS COLLECTIONS 

VOLUME 81, NUMBER 10 



TROPISMS AND SENSE ORGANS OF 
LEPIDOPTERA 



BY 
N. E. McINDOO 

Senior Entomologist, Deciduous-I'"i nit Insect Investigations, 
Bureau of Entomology, U. S. Department of Agriculture 





WMW 



(Publication 3013) 



CITY OF WASHINGTON 

PUBLISHED BY THE SMITHSONIAN INSTITUTION 

APRIL 4, 1929 



t APR5-k 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOLUME 81, NUMBER 10 



TROPISMS AND SENSE ORGANS OF 
LEPIDOPTERA 



BY 
N. E. McINDOO 

Senior Entomologist, Deciduous-Fruit Insect Investigations, 
Bureau of Entomology, U. S. Department of Agriculture 




(Publication 3013) 



CITY OF WASHINGTON 

PUBLISHED BY THE SMITHSONIAN INSTITUTION 

APRIL 4, 1929 



Z^c Bovb (^aPfttnorc (preee 

BALTIMORE, MD., O. 8. A, 






TROPISMS AND SENSE ORGANS OF LEPIDOPTERA 

By N. E. McIndoo 

senior entomologist, deciduous-fruit insect investigations, bureau of 
entomology, u. s. department of agriculture 

CONTENTS 

PAGE 

Introduction 2 

A. Tropisins 2 

I. Phototaxis 3 

1. Review of literature : 3 

(a) Definitions and problems in the study of light reactions... 3 

(b) Are light reactions adaptive ? 4 

(c) Is orientation accomplished by selection of trial movements? 5 

(d) How do light rays bring about orientation? 5 

(e) Do circus movements support Loeb's theory? 5 

(f ) What wave lengths stimulate insects most? 6 

(g) Light traps are not yet considered successful 9 

2. Phototactic experiments on codling-moth larvae 10 

II. Chemotaxis 14 

1. Review of literature 14 

2. Chemotactic experiments on codling-moth larvae 17 

III. Geotaxis 19 

1. Review of literature 19 

2. Geotactic experiments on codling-moth larvae 20 

IV. Thigmotaxis 21 

1. Review of literature 21 

2. Thigmotactic experiments on codling-moth larvae 22 

B. Tropic receptors 22 

I. Photoreceptors 23 

II. Chemoreceptors 24 

1. So-called olfactory organs 24 

(a) Antennal organs 24 

(b) Olfactory pores 27 

2. So-called taste organs 35 

III. Audireceptors 39 

1. Tympanic organs 41 

2. Chordotonal organs 41 

3. Johnston organs 42 

4. Auditory hairs 44 

IV. Thigmoreceptors 45 

I. Tactile organs 45 

V. Georeceptors 46 

I. Balancing organs 46 

VI. Other receptors 47 

C. Scent-producing organs 48 

Summary and discussion 51 

Literature cited 53 

Smithsonian Miscellaneous Collections, Vol. 81, No. 10 

I 



2 smithsonian miscellaneous collections vol. 8l 

Introduction 

Entomologists know considerable about the behavior of insects, but 
are still unable to explain many of their activities. Since insects are 
cold-blooded animals and their anatomical organization is entirely 
different from that of higher animals, their responses to environmental 
conditions are different. For this reason their activities are not so easily 
understood. Most of their reactions are tropic responses to external 
stimuli. We know considerable about some of our own external stimuli, 
such as light, sound, and heat, and how they affect us ; but we know 
very little about the external stimuli which cause responses in insects, 
and we know still less about the sensory impressions which are 
produced in them by these stimuli. 

When it is desired to control an insect, the first step is to study its- 
life history, which is largely a study of its behavior, and in turn 
behavior is largely a result of tropic responses. A study of tropisms 
is, therefore, a basic one, but economic entomologists in their haste to 
obtain practical results usually overlook this fact. The late Jacques 
Loeb was our greatest advocate of the study of tropisms, and as a 
result of his indefatigable efforts there has arisen a much broader 
and more important subject — general physiology. If entomologists 
would study tropisms more seriously, using the best equipment obtain- 
able, they would certainly obtain much information which could be 
used in insect control. 

The object of this paper is to bring together the available informa- 
tion on the tropisms and sense organs of Lepidoptera, hoping that this 
information will encourage a more serious study of tropic responses. 
At the suggestion of Dr. A. L. Quaintance, Associate Chief of the 
Bureau of Entomology, the writer began a series of studies dealing 
with the tropisms of various insects, particularly those of the codling 
moth. The results herein discussed include those obtained by the 
writer in his studies on Lepidoptera and a review of the literature, 
most of which pertains only to butterflies and moths. 

A. Tropisms 

The term tropism comes from the Greek word meaning " turn." 
According to Mast (56, p. 53) it was first used in 1832 by DeCandolle, 
who called the bending of plants toward light heliotropism. Later 
the word heliotropism came to signify both the bending and the ex- 
planation of the process. \^erworn and Loeb, in 1886 and 1887, as 
cited by Mast, using tropisms as a basis for investigation, were the 
first to study animal behavior from the physico-chemical point of 



NO. 10 TROPISMS OF LEPIDOPTERA — McINDOO 3 

view. Loeb attempted to show that the behavior in plants and animals 
is practically alike, and concluded that the behavior in animals is 
largely controlled by external agents, and is influenced by internal 
factors. He and his followers described reactions in animals in terms 
of tropisms. 

There has been a controversy among various classes of scientists 
in regard to the proper terminology to be used in connection with 
tropic responses. Couch (6) proposes that the generic name, tropism, 
be retained for all the classes, but that biologists and biochemists use 
the words phototaxis, geotaxis, chemotaxis, etc., leaving the " isms " 
to be used by chemists and physicists, and particularly the word 
phototropism by the photochemist. 

Mast (57) informs us that the term tropism has been defined in 
some 20 difl^erent senses. Since there is so much confusion about its 
meaning, he proposes that we cease using it altogether, using instead 
terms with more precise meanings as (p. 261) : " negative or positive 
orientation or reaction to light, gravity, etc. ; photo-, geo-, etc., negative 
or positive ; or merely negative or positive reactions to light, gravity, 
chemicals, etc." In the following discussions these suggestions will 
be frequently followed, and instead of saying that an insect is nega- 
tively or positively phototropic or phototactic, it will be said to respond 
or react negatively or positively to light, or to be photonegative or 
photopositive. 

I. PHOTOTAXIS 

I. REVIEW OF LITERATURE 

(a) Definitions and problems in the study of light reactions. — The 
terms heliotropism and phototropism have been generally used by 
both botanists and zoologists, but as already mentioned, Couch pro- 
poses that biologists use the word phototaxis, leaving the former terms 
for the photochemist. Botanists still insist on using them, but recom- 
mend that zoologists should say phototaxis and phototactic. According 
to Mast (56, p. 253) the botanists are correct, because 

Organisms which orient and move toward or from a source of light are usually 
termed phototactic, those which orient but do not move as phototropic, and those 
v/hich do not orient but still react have been termed photopathic. 

Loeb, discussing both plants and animals, used the word helio- 
tropism in his original German publications, in their English transla- 
tions, and even in his latest papers. For our purpose here Loeb's 
definition of phototaxis will suffice. He says (43, pp. 135, 139) : 

Heliotropism covers only those cases where the turning to the light is com- 
pulsory and irresistible, and is brought about automatically or mechanically by 



4 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

the light itself. ... If the current curves of radiating energy, e. g., light rays, 
strike an animal on one side only, or on one side more strongly than on the sym- 
metrical side, the velocity or the kind of chemical reactions in the symmetrical 
photosensitive points of both sides of the body will be different. The consequence 
will be in a positively heliotropic animal a stronger tension or tendency to con- 
tract in the muscles connected with the photosensitive points of the one side of 
the body than in those connected with the opposite side. 

Mast (56, pp. 57, 58) points out several problems in the study of 
light reactions which entomologists should carefully consider. They 
are discussed with others as follows : 

(b) Are light reactions adaptive f — No, according to Loeb's defini- 
tion. He says that animals go toward light neither because it is useful 
for them to do so nor because they enjoy it, but because they are 
photopositive. Mast strongly refutes this explanation by saying (56, 
pp. 298, 237) : 

Reactions to light are in general adaptive. There are, however, certain reac- 
tions which are clearly injurious and often fatal; as, for example, the flying of 
insects into a flame and the positive reactions of organisms which live in dark- 
ness. But the positive reactions of insects are ordinarily advantageous. It is 
only under artificial conditions that they prove fatal, and the ancestors of many 
animals which now live in darkness lived in the light. Positive reactions were 
probably advantageous to them, and the power to respond thus was probably 
inherited by the offspring, in which it is useless. . . . Negative response to light 
tends to keep these creatures [blowfly larvae] buried in cadavers where they find 
food. It is ordinarily only under artificial conditions that the reactions of organ- 
isms to light prove fatal. Positive reactions to candle, lamp and lighthouse de- 
stroy untold numbers of moths and flies and bees and beetles and birds, but who 
has seen such fatalities under natural conditions? Under such conditions the 
responses to light direct these animals to the advantage of their well-being. 

Loeb's (43, p. 160) explanation of the origin of adaptive light 
reactions follows : 

The fact that cases of tropism occur even where they are of no use, shows 
how the play of the blind forces of nature can result in purposeful mechanisms. 
There is only one way by which such purposeful mechanisms can originate in 
nature ; namely, by the existence in excess of the elements that must meet in 
order to bring them about. 

Mast (56, p. 368) adds that light reactions are variable, modifiable, 
and in general adaptive, and that regulation constitutes perhaps the 
greatest problem of life. Loeb (43, p. 125) believes there is a photo- 
tactic difiference between the sexes of Lepidoptera, for male moths are 
more apt to fly into candle flames than are the females. It is well 
known, however, that both sexes are attracted to strong electric lights. 
It was assumed long ago that moths fly into flames because they are 
fond of light, but Loeb assures us that this is a purely mechanical 



NO. 10 TROPISMS OF LEPIDOPTERA — McINDOO 5 

response, comparable to the turning of a plant toward light. In reply 
to the question as to why moths fly toward a candle at night and not 
toward the moon, Mast (p. 227) replies that in moonlight there are 
large illuminated areas all about, whereas in candle light the objects 
are so faintly lighted that moths do not react to light reflected from 
them. In reply as to why mourning-cloak butterflies fly toward a large 
illuminated patch of flowers rather than toward the sun which is much 
brighter, Parker (69) says it is because the patch of flowers makes a 
larger " spot on the retina," All of these responses Mast considers 
adaptive regardless of the explanations given. 

(c) Is orientation accomplished by selection of trial movements? — 
Loeb (42, p. 57) exposed blowfly larvae in front of a window. He 
found them to be photonegative and to crawl with mathematical 
precision. Other investigators have repeated these tests, but they 
failed to find that blowfly larvae, or in fact any other insects, respond 
to light with mathematical precision. Mast (56, p. 196) says that 
blowfly larvae are excellent examples of animals which are guided 
fairly directly on their courses by successive trial movements. 

Loeb (42, p. 24) tested caterpillars of Euproctis (Porthesia) 
chrysorrhoea and he found them to be strongly photopositive, creeping 
in a straight line toward the light. Lammert (40) in 1925 tested three 
other species of caterpillars which were also photopositive, but crawled 
in wavy lines. The present writer's results (p. 13) with codling-moth 
larvae agree with those of Lammert. 

(d) Hoiv do light rays bring about orientation? — Loeb in 1888, 
according to Mast (56, pp. 54, 57, 228-235), claimed that orientation 
in animals is controlled by the direction in which the rays pass through 
the tissue. In 1889 he further said that symmetrically located points 
on the photosensitive surface must be struck by light at the same angle. 
Later he abandoned the idea of the importance of the angle between 
the sensitive surface and the light rays and substituted the view that 
orientation is brought about by absolute difference of intensity of the 
light on symmetrically located points on the sensitive surface. 
Jennings, Mast, and others claim that orientation is accomplished by 
changes of intensity on the sensitive surface. Loeb believed that light 
acted constantly as a directive stimulation similar to the action of a 
constant current of electricity, while Jennings and Mast believe that 
it acts only when the animal turns out of its course so as to produce 
changes of intensity. 

(e) Do circus movements support Loeb's theory? — Mast (56, 
pp. 215-218) states that several workers have found that if one of 



6 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

two symmetrically located sense organs has been prevented from func- 
tioning, the animal no longer orients but turns toward one side when 
stimulated. Certain flies with one eye blackened turned toward the 
functioning eye. Parker (69) obtained similar results with a butterfly 
{Vanessa antiopa). Loeb (44, pp. 52-61) cites the results of several 
writers, who conducted similar tests on insects, as giving " direct proof 
of the muscle tension theory of heliotropism in motile animals." 
Dolley (10) experimented with Vanessa antiopa and concluded that 
his results contradicted Loeb's " continuous action theory." According 
to this view the tension of the muscles of the appendages on both 
sides of the body is controlled through direct reflex arcs by the photo- 
chemical changes produced by light in the two retinas. Dolley says 
that these butterflies with one eye blackened can orient and can turn 
under certain conditions toward either side, all of which indicates 
that orientation in them is not wholly dependent upon the relative 
intensity of light on the two eyes. The same author (11) determined 
that J\inessa antiopa moves faster in weak light than in strong light. 
This behavior is not in accord with the above theory. Dolley also 
determined that these butterflies move faster in intermittent light than 
in continuous light, which indicates that orientation in them is " due 
to the time rate of change of intensity." 

(f) What ivave lengths stimulate insects most? — The determining 
of this is perhaps the most difficult of all the problems encountered 
in a study of tropisms, and much confusion has arisen while trying 
to solve it. Many erroneous conclusions have been derived ; first, 
because the investigators, as a rule, have had a poor knowledge of the 
physics of color ; and second, because in most cases they have not been 
properly equipped with apparatus to study the effects of various wave 
lengths on insects. 

Loeb (42, p. 18) remarks that all authors who have studied the 
behavior of plants behind screens have usually concluded that only 
the more refrangible rays are heliotropically active. Using two colored 
screens (red and blue), he concluded that the more refrangible rays 
of the visible spectrum are more effective than the less refrangible 
rays in causing orientation in animals (p. 82). He tested the cater- 
pillars of Euproctis chrysorrhoea (pp. 29-31) with these screens, 
which had been examined spectroscopically, and determined that they 
reacted most decidedly to the shorter wave lengths. 

Mast (56, pp. 302-365) in 191 1 reviewed the entire subject of wave 
lengths or colors and discussed insects in particular (pp. 343-355)- 
He reviewed Loeb's work on animals and fails to understand how the 



/-'tik 



NO. lO TROPISMS OF LEPIDOPTERA McINDOO 7 

latter could have made such positive statements since only two colors 
were used. It is easy to ascertain that animals can distinguish wave 
lengths that we call colors, but it is difficult and perhaps impossible 
to determine whether the responses are brought about by the quality 
or quantity of the wave lengths, that is, by actual color or by bright- 
ness. Our only recourse is to test them and to judge their responses 
from the human point of view, which proves little or nothing in regard 
to insects. On this point Mast (p. 362) says: 

Bees and fishes can undoubtedly distinguish different regions in the spectrum. 
They can be trained to select any of the primary colors of the spectrum by asso- 
ciating these colors with food. That is, they are positive to (or select) one color 
at one time and. another at a different time. Just what mechanism is involved in 
this power of selection is unknown. Whether it is on the basis of brightness or 
on the basis of color vision or neither is a matter concerning which experimental 
evidence does not warrant a definite conclusion. Many organisms react to ultra- 
violet much as they do to visible rays. This is in harmony with the following 
quotation from Schafer referring to man (1898, p. 1055) : "The invisibility of 
the infra-red rays is probably due to insensitiveness of the retina, while the 
ultra-violet rays fail to be seen, partly, at any rate, owing to absorption by the 
ocular media." 

Washburn (90. pp. 144-159) discusses the problem of visual quali- 
ties in invertebrates. Certain authors believe that vision as far as 
color is concerned in the lower animals, particularly insects, is similar 
to that in totally color-blind people. On this point Washburn (pp. 145, 
147, 148, 157) says: 

It is therefore of some importance to the problem of color vision in the lower 
animals to find hoiv strongly the light rays of various wave-lengths affect them. 
But we must bear in mind that for the lower animals it is impossible to conclude 
color-blindness from the fact that the brightness values, that is, the effective 
intensities, of the different colors are what they would be for a color-blind human 
being. Just this unsafe inference is, however, drawn by certain authorities. . . . 
It is thus clear that when an animal discriminates between rays of different 
colors, the discrimination may be based merely on the intensity of the rays, 
either in themselves or in the effect which they have on the organism, rather than 
on their wave-length or color. . . . He [Hess] found that the yellow and green 
rays produce much more effect than the red and violet rays. Since this is true 
also of the color-blind human eye, he argues that the animals tested are totally 
color-blind. He holds, in fact, that all invertebrate animals are totally color- 
blind, on the same evidence. . . . But again we may remind ourselves that it 
does not follow that because a human being who finds the yellow-green, rather 
than the yellow, the brightest spectral region, is totally color-blind, therefore an 
animal, especially an invertebrate animal, the chemical substances in whose eye 
may have no resemblance to those in the human eye, is color-blind if it shows 
these reactions to the different regions of the spectrum. 

Mayer and Soule (59) in 1906 determined that the caterpillars of 
the milkweed butterfly are photopositive to ultraviolet rays, but barely 
respond to the rays which man sees in the spectrum. 



8 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

Lutz (46) in 1924 used colored filters as windows in a box and 
determined that insects can readily distinguish ultraviolet rays. Certain 
individuals, particularly Lepidoptera, stubbornly refused to respond 
to any condition of illumination, even clear sunshine, when they were 
placed in the box. Certain others responded only when urged to do so 
by jarring the box, but then their reactions were definite. The skipper 
Epargyreus titynis, when put in the box " went to sleep," but when 
touched it went to the ultraviolet filter and tried to get out. 

Other recent workers, whose apparatus and procedure are recom- 
mended to research students, have obtained results showing that insects 
respond to the color of certain wave lengths. Thus Abbott ( i ) deter- 
mined that a certain ant responds most readily to yellow, and Ber- 
tholf (3) ascertained that red does not stimulate honeybees as much 
as it does humans, but that violet stimulates them more. 

Besides consulting the references already cited students are advised 
to consult others, particularly Parsons (71) and Luckiesh (45). 

One of the most recent papers on this subject is by Peterson and 
Haeussler (74), who studied the responses of the oriental fruit moth 
(Laspeyresia molesta Busck) and the codling moth {Carpocapsa 
pomponella L.) in 1925, 1926, and 1927. Several thousand individuals 
of each species were tested after dusk at Riverton, N. J., where 
an abundance of material could be secured. Two types of apparatus 
were used, but the most satisfactory one is what they call a " four- 
way light apparatus." The colored screens and lights used were sub- 
mitted to Dr. P. A. van der Muelen of Rutgers University, who 
examined them spectroscopically. Their summary in part is as fol- 
lows : Oriental fruit moths and codling moths seek the light side of 
containers in which they are placed. This indicates that they are 
photopositive under ordinary conditions. When tested under labora- 
tory conditions in the four-way light apparatus, with the four compart- 
ments equally lighted with white lights, practically the same number 
of moths went into each compartment. When the compartments were 
unequally lighted, the largest number of moths went to the strongest 
light. When the moths were given the choice of lights varying in color 
from red to violet and the ratios of relative intensities of the colored 
lights were approximately equal, practically all of the motljs went 
to blue and violet lights. Few or none were attracted to the red light. 
Orange and yellow lights, when compared to bluish ones, were also 
unattractive. Green light, possessing no blue rays, was likewise un- 
attractive. Violet light was preferred to blue, and ultrapurple wave 
lengths appeared to be more attractive than violet. Ultraviolet light 



NO. 10 TROPISMS OF LEriDOPTERA — McINDOO 9 

was probably perceived by oriental fruit moths and they were probably 
attracted by it. Codling moths seemed to be more strongly photoposi- 
tive to blue and violet lights than were oriental fruit moths. The 
responses of males and females of both species to colored lights ap- 
peared to be similar. Experiments in which ordinary electric lights 
were installed in a peach orchard were unsuccessful, only a few of 
the oriental fruit moths being caught in traps. Codling moths were 
not tested in orchards. 

There is considerable difiference of opinion regarding the apparatus 
to be used in light experiments. Yerkes and Watson (91, p. 3) say 
that simpler and more conveniently manipulated apparatus may be 
used in preliminary work, but emphatically recommend that such 
apparatus be abandoned as soon as possible. They recommend a very 
complicated piece of apparatus for thoroughgoing, intensive, and 
quantitative work. 

(g) Light traps are not yet considered successful. — Dewitz (9) in 
1912 briefly discussed the practical side of phototaxis as applied in 
economic entomology, but regretted that this subject had never been 
seriously studied from a scientific point of view. To his knowledge 
only one investigator spectroscopically examined the various lights 
used. This man projected a large spectrum on a screen in a dark room 
and then observed certain moths collect on the different colors of the 
spectrum. He found that the less refractive colors (red to green) 
exercised by far the strongest attraction. It is also stated that experi- 
ments were conducted in vineyards in Germany in which lamps pro- 
vided with glass covers of various colors were used. The lamps with 
green glass attracted the largest number of moths. 

According to Dewitz, artificial light as a control measure was first 
used in 1787 for attracting vine moths to lighted candles on window 
sills and to wood fires in vineyards. Since that date light traps have 
been gradually developed and improved until to-day there are many 
types and varieties of kerosene, acetylene, and electric lamps used for 
this purpose. It seems that none, however, has given complete satis- 
faction as a control measure. The present writer does not know of a 
single authentic report that this method has been successful on a large 
scale, although he has a recent newspaper report stating that along 
the German-Polish frontier powerful searchlight traps have been used 
successfully against a nocturnal moth whose larvae ravage the pine 
forests. Millions of moths are said to have been cremated by being 
attracted to flames near the searchlights. 



lO 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 



At last an investigation on a large scale, in which up-to-date scientific 
methods are being used, has been started l)y the New York (Geneva) 
State Agricultural Experiment Station and the Empire State Gas and 
Electric Association. So far only a progress report of this work has 
been presented by Parrott (/O), who regards a study of tropic re- 
sponses of insects as one of the most promising fields of entomological 
inquiry, and who believes that when the more important facts about 
light attraction for insects are known we may, perhaps, be able to 
change some of our present practices on insect control. Experiments 
in orchards in which various kinds and colors of electric light bulbs 
were used gave a total catch of 65,000 insects, of which 29.6 per cent 
were Lepidoptera and 52.5 per cent were Diptera. All of the Lepi- 
doptera, most of the Coleoptera and Hemiptera, and a smaller per- 
centage of the Diptera and Hymenoptera caught were injurious 
species. Among the Lepidoptera were the codling moth, fruit-tree 
leaf-roller, cutworm moths, and several other species. This method 
was also found useful for trapping codling moths and other injurious 
insects in cold storage houses. In a dairy barn clear and white frosted 
bulbs attracted more flies than did the other colors, and red attracted 
the least of all. Tests in which colored glass filters were used with 
several species of moths including codling moths and European corn- 
borer moths showed that these insects did not respond to the red end 
of the visible spectrum, but the light yellow, light blue-green or day- 
light, red-purple, and blue-purple filters proved the most attractive. 

2. PHOTOTACTIC EXPERIMENTS ON CODLING-MOTH LARVAE 

The writer, like other observers, has found the adult codling moth 
an unfavorable insect on which to experiment in the laboratory. These 
moths are extremely erratic in behavior. They are very quiet and 
usually non-responsive during the daytime, but at dusk and later they 
are more active and readily respond the first time, although thereafter 
their responses are irregular and not fully reliable. Since the same 
individuals cannot be repeatedly tested with satisfaction and as the 
writer's supply of them was limited, he was not able to conduct the 
experiments as originallv planned. 

Having failed to obtain definite results by testing a small number 
of the adults, the writer spent much time in 1927 on the larvae, 
which proved to be more favorable material for tropic tests. In all 
154 larvae, belonging to the two broods at Silver Spring, Md., were 
tested in the laboratory under various conditions. Most of them 
had been reared from eggs in the laboratory. The wormy apples 



NO. lO TROPISMS OF LEPIDOPTERA — McINDOO II 

were kept in battery jars and drinking glasses, and an accurate record 
of the age, size, color, and behavior of the infesting larvae was 
recorded. The instars were determined by use of Dyar's (14) method 
of head measurements, the live larvae being rendered inactive by 
laying them upon a piece of ice on the microscope stage. Temperature 
and humidity records were obtained from centigrade thermometers 
and a h}grothermograph. Notes pertaining to the date, time of day, 
character of sky and wind, degree of brightness of sunshine, and 
rainfall were recorded, but unfortunately it was difficult and some- 
times impossible to correlate climatic conditions with the tropic re- 
sponses obtained. For this type of work more refined methods and 
apparatus are badly needed. 

Since it was not possible to carry on phototactic tests among the 
trees in orchards in the natural environment of these insects, the 
next best condition was to use daylight in the laboratory. Daylight, 
however, was unsatisfactory because the intensity varied daily and 
even from hour to hour, so that comparative quantitative results 
were impossible. Artificial light with a lOO-watt " daylite " bulb was 
tried. The larvae usually responded to it only after being touched 
and then very feebly. For these experiments a simple and quick 
method for determining daylight intensities was badly needed, but 
none seemed available. 

Relative to ecological photometry and means of measuring light, 
Klugli (39) presents a critical review of the entire subject and then 
describes a new instrument, called an ecological photometer. There 
are already three kinds of instruments of high precision for measuring 
radiation. Two of them, the pyrheliometer and spectrobolometer, are 
used by the astrophysicist and the third, the spectrophotometer, is 
employed by the physicist. The new instrument is said to meet the 
needs of the ecologist, but in order to operate it one should be con- 
siderably experienced in photography. Using the new instrument 
Klugh obtained very interesting results. As an example to show the 
great variations in daylight intensity, he selected an open habitat on a 
bright clear day, July 26. Letting the intensity at noon equal 100 per 
cent, he then determined the following percentages of intensities : At 
9 a. m., 90 per cent ; at 5 p. m., 83 per cent ; at 6 p. m., 66 per cent ; 
and at 7.45 p. m., 5.2 per cent. On another bright sunshiny day he 
found the intensity to be only 2 per cent in a woods while in the open 
it was 100 per cent, but on a cloudy day it was 10 per cent in the 
same woods as compared to 100 per cent in the open. The intensities 
on clear and cloudy days vary greatly. Filmy clouds over the sun 



12 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

reduce the intensity, whereas white clouds in the sky but not over the 
sun increase it by reflection from lo to 40 per cent over that of a 
cloudless day. 

In view of the varying light values and other conditions involved in 
phototactic experiments, the reader can appreciate the experimenter's 
difficulties and can understand why it is so difficult to interpret the 
results correctly. 

In bright light, although not direct sunshine, codling-moth larvae 
of the first instar were found to be weakly photopositive, and their 
reactions agreed in general principles with those described by other 
investigators. None was found, however, to orient and to move with 
mathematical precision as was stated by Loeb for certain insects. 

Larvae of the first instar, confined in an uncovered box in which 
most of the light was reflected from the ceiling, moved in all direc- 
tions. Recently hatched larvae placed on a table by a south window 
and six feet from an east window, instead of moving directly toward 
the south window, deviated toward the left (fig. i, A). This reaction 
agrees with those described by other writers, for example Dolley (12), 
when two sources of light at right angles are employed. 

In order to eliminate side lights a box, 18 inches long, 12 inches 
wide, 12 inches high, and lined with a dead-black cloth, was con- 
structed. One end and the top were left open. The open end faced 
the south window while the experimenter, from above, traced the 
tracks of the insect with a pencil. Since there was apparently no 
difference between white paper and black paper as to effects of reflected 
light on the insect, all tracings were made on white paper. The pencil 
was moved gently a few millimeters behind the insect and this usually 
did not affect the behavior of the larva, although in tracing the path 
of photonegative insects care had to be exercised not to allow shadows 
from the pencil to fall upon the insect. Recently hatched larvae, when 
put in this phototactic box on either bright sunshiny days or on cloudy 
days, oriented themselves and tended to move toward the direct rays 
of light as illustrated in figure i, B, in which those tested before 
noon deviated toward the left (No. p6) while those tested after noon 
deviated toward the right (Nos. p8, pp). Many exceptions to this 
tendency, which the writer cannot explain, were recorded, so no 
definite rules can be stated. In order to be reasonably certain about 
the light reactions of all the larvae tested, it was necessary to test each 
one two or more times before drawing conclusions. 

Larvae of the second, third, and fourth instars were found to be 
weakly photopositive to weak light (fig. i, C, Nos. 112a, lija, I2^a), 
but indift'erent to strong light (Nos. ii2h, iijb, 124b). 



NO. lO 



TROPISMS OF LEPIDOPTERA McINDOO 



13 



Larvae of the fifth instar sometimes acted indifferently to light 
(fig. I, D, No. 108) hut generally were weakly photonegative (Nos. 
102, 118, 126, I2p). Larvae of the sixth instar were either weakly 
(fig. I, E, No. 100) or strongly photonegative (Nos. 34, 68, 72, /j, 
78), the degree depending on their age. In all cases they oriented 
quickly and moved hurriedly from the light as illustrated in figure i, E. 




'/Ji /^ 


rx/ 


"*x ^ 


w 


/ifir / 


\. ) 


//JV__/ 


/ 





D F 

Fig. I. — Tracings of phototactic responses of codling-moth larvae (see p. 12 
for further explanation) . A, Movements of recently hatched larvae of first 
brood tested on table betv^-een an east and a south window at 3.45 P. M. B, Re- 
cently hatched larvae of second brood tested in phototactic box. C, Larvae of 
second brood ; Nos. 112 a and h, fourth instar ; Nos. lis « and h, third instar ; 
and Nos. 124 a and b, second instar. D, Larvae of second brood, fifth instar. 
E, Larvae of second brood, sixth instar, fully grown. F, Fully grown larva, 
No. IS4, ready to spin ; a and b, normal ; c to /, ocelli blackened. 

Normal larvae of the sixth instar, ready to spin cocoons, were 
strongly photonegative (fig. i, F, No. 154a and b), but when their 
ocelli were covered with a mixture of glue and lamp black they became 
indifferent to light as illustrated in figure i, F, c to /. 

One of Loeb's early observations indicated to him that lepidopterous 
larvae do not generally react to geotaxis, but that this tropism is 
replaced by phototaxis. According to Lammert (40), Schmitt- 
Auracher, after finding a migration of pigment in the ocelli of insects, 
supported this view and then assumed that the ocelli were capable of 



14 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

two adaptive conditions, which are distinguished morphologically by 
different pigment deposits and that phototaxis depends on these 
deposits ; that is, a dark deposit of pigment causes a dark adaptation 
and negative phototaxis, while a light deposit brings about a light 
adaptation and positive phototaxis. Lammert does not support this 
hypothesis because he failed to find a migration of pigment in the 
ocelli of certain insects, but his tests in which the ocelli were blackened 
caused him to believe that lepidopterous larvae have two kinds of 
photoreceptors — the ocelli and others lying in the body integument. 
He believes, therefore, that these larvae have a skin sensitive to light. 
The present writer's few experiments on this subject do not indicate 
that codling-moth larvae have photoreceptors in their integument, and' 
these larvae do not appear to be suitable material in which to search 
for a migration of pigment in their ocelli. 

II. CHEMOTAXIS 

I. REVIEW OF LITERATURE 

Much was learned about chemotaxis long before the term chemo- 
tropism was first applied to it. Among the earliest publications are 
those of Fabre (20, pp. 179-216) and Forel (21, p. 76), who estab- 
lished the fact that male moths are attracted from long distances to 
their mates apparently by means of odors emitted by the females. 
Mayer (58) in 1900 carried on tests with promethea moths and estab- 
lished the fact beyond doubt that the males are attracted by emana- 
tions from scent-producing organs of the females. Later Mayer and 
Soule (59), Kellogg (27), Freiling (23), and others corroborated the 
view that the emanations are emitted from scent-producing organs. 
Priiffer (75, 76) more recently has supported this view in regard to 
the gipsy moth. He assures us that the attraction between the sexes 
is accomplished by means of aromatic substances which are secreted 
by the females and the odors of which are perceived by the males. To 
determine whether or not the attraction is similar to the radiation from 
radioactive material, he confined the females in a lead cylinder which 
would reduce the supposed radiation to a minimum and then allowed 
the emanations from the cylinder to escape by means of a specially 
constructed column of mercury. Using this apparatus he soon deter- 
mined that the females thus confined attracted the males in the same 
manner as do the females in the open air, but that the males were not 
attracted when the females were confined in a hermetically sealed glass 
container. Dead females were also able to attract males, but to a 
lesser degree. Priiffer furthermore tells us that the radiation from a 



NO. lO TROPISMS OF LEPIDOPTERA MclNlXJO I5 

living insect, which when laid upon a photographic plate leaves an 
impression, plays no part in this attraction. 

Loeb (43, p. 155) in 1889 seems to have been the first one to use 
the term chemotropism in connection with the responses of Lepi- 
doptera that have just been discussed and with the attractiveness which 
meat has for blowflies and their larvae. 

As the writer (54, 55) has recently reviewed the literature dealing 
with chemotaxis in economic entomology, only a short discussion need 
be given here. 

Chemotaxis, like the other tropisms, has two divisions. Attrahents, 
usually called " attractants," induce positive chemotaxis and repellents 
induce negative chemotaxis. For our purpose here Tragardh's (85) 
definition will suffice. He says (p. 113) : 

By the term " chemotropism " is meant, as well known, the automatic orien- 
tation of the animals to any olfactory sensation in such a manner that both sides 
of the body are struck by the lines of diffusion at the same angle. Theoretically, 
when a substance diffuses an odour, fine particles are ejected in straight lines, 
but in reality the air currents cause the Ijnes to deviate from their straight track. 

In the control of Lepidoptera many practical applications of chemo- 
taxis have been made. Attractive poisoned bran baits are used as 
control measures against armyworms and cutworms. As early as 1896 
baited traps were used by collectors to catch large numbers of fer- 
tilized, egg-laying female moths. Many years ago the common control 
method against grapevine moths in Europe was the use of attractive 
baits ; but more recently the use of insecticides has supplanted this 
method as a control measure, so that now it seems to be used only as 
an indicator of the approximate number of moths present. With this 
information the grower knows when to apply the insecticides. 

A molasses-yeast bait was placed by Peterson {72) in a peach 
orchard in New Jersey, and it was observed that large numbers of the 
oriental fruit moth came to the bait pans. This observation was a 
stimulus for more extended work with attractive baits, but this par- 
ticular bait when fermenting proved to be the most attractive one 
tested. Frost (24) used weak acids, volatile oils or their constituents, 
sugars, and molasses as attractants. The fermenting sugar baits 
attracted the most moths. Peterson (73) tested about 250 aromatic 
chemicals as possible attractants for the oriental fruit moth. Terpineol 
and several essential oils were somewhat attractive, but not so attractive 
as several fermenting sugar-producing products. Fermenting fruits 
(dried fruit in water), particularly prunes, pears, and apricots, at- 
tracted large numbers of moths. By using dried fruits, sugars, and 



l6 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

sirups in Maryland peach orchards in 1926, Siegler and Brown ob- 
tained results similar to those of Peterson. Apricots were the most 
attractive of the dried fruits used. A late report about baits for the 
oriental fruit moth is by Frost (25), who discusses comparative tests 
with various baits, factors affecting the catches of moths, and the 
value of bait pails as a means of control. He believes that this method 
may find a definite place in the control of this moth. The latest report 
consulted on this subject is by Stear (83), who says that bait pans 
offer little hope in practical control. 

Supposing that the codling moth was attracted to fruit trees by 
odors, Yetter (92) conducted a large series of experiments in Colo- 
rado, using 35 aromatic chemicals. Of these only five attracted moths 
in sufficient numbers to give promising results. These five are isobutyl- 
phenyl acetate, diphenyl oxide, bromo styrol, benzyl benzoate, and 
safrol. He firmly believed that, if trapping were systematically carried 
out by all the growers in the Grand Valley and for the entire season, 
much could be accomplished in checking the damage done by this pest. 

Yetter and Yothers each seem to have begun testing baits in 1923, 
but the latter did not publish his results until 1927. Yothers' (93) 
summary follows in part : Cooked, fermented apple juice, containing 
some of the apple pulp, proved more attractive than did vinegar or 
cider. A molasses ferment proved much more effective than did apple 
ferment, honey ferment, or any one of two dozen essential oils. 
Of the essential oils only three — clove, citronella, and sassafras — 
proved attractive to codling moths. About 55 or 60 per cent of the 
moths caught were females, and 95 per cent of these were gravid. 
The baits gave a good indication of the beginning and end of the 
codling-moth season, the appearance of each brood, and the maximum 
abundance of each. This information may be used to advantage in 
arranging spray dates for moth control. In bait tests final counts of 
fruit showed an increase of from 12 to 16 per cent of fruit over similar 
plots without traps. Yothers believes than an attractive bait may yet 
be discovered which will be so attractive that this method may then be 
recommended as a satisfactory supplementary control measure. 

Yetter's first report encouraged others to try this supplementary 
control measure. Spuler (82) found codling moths to be attracted in 
large numbers to a fermented bait consisting of one gallon of apple 
cider, one-half pound of brown sugar, and one yeast cake. Approxi- 
mately 60 per cent of the moths caught were females. It was concluded 
that the bait traps will reduce the number of moths in an orchard, thus 
serving as an important supplement to spraying, and will furnish infor- 



NO. 10 TROPISMS OF LEPIDOPTERA — McINDOO I7 

mation as to the time of appearance of the moths. Other similar 
reports on this subject are by Headlee (30) and by List and 
Yetter (41). According to Fowler (22), baits are also being- used 
in South Australia as an aid in codling-moth control. This writer 
says that large numbers of moths can be caught in suitable traps 
properly baited, and that it is profitable to put out a number of 
traps from the last week in October until the end of November, and 
again from the end of January to the middle of February, which 
intervals cover the periods of maximum emergence and give the best 
results. Baits are likewise being used in South Africa. 

After experimenting with a large number of aromatic substances 
for several years at Clarksville, Tenn., Morgan and Lyon (67) have 
recently reported that amyl salicylate incites a decided feeding response 
in tobacco hornworm moths (PlilcgctJwntitis Carolina), inducing an 
attraction to artificial flowers. Sixteen species of Sphingidae were 
caught in traps baited with the chemical besides the two species 
frequenting tobacco. In field experiments a number of female moths 
sufficient to have deposited 8.1 eggs per tobacco plant were caught in 
traps. Amyl benzoate was also found very attractive. 

Attractants and repellents have been used in control measures 
against other species of moths, and a further discussion is perhaps 
not necessary to convince the reader that this new line of research 
merits further serious consideration. 

2. CHEMOTACTIC EXPERIMENTS ON CODLING-MOTH LARVAE 

The preliminary results which follow were obtained by testing 
codling-moth larvae with attractants and repellents. As an example 
of the procedure in the tests, a recently hatched larva was put in the 
phototactic box described on page 12 to be sure that it responded 
normally to light. After tracing its tracks (fig. 2, A, a) a sheet of 
white paper was laid on the table by the south window. Twelve cubes 
of green apple, each 4 or 5 millimeters in size, were placed an inch or 
more apart on the paper inside a circle having a diameter of 5 inches 
(fig. 2, A). The larva was then placed inside the circle and allowed to 
search for the pieces of apple while slowly moving toward the light. 
It was given 10 chances and each time it touched a piece of apple or 
the circle that particular chance ended. Pieces of cork of the same 
size as those of the apple and squares equally large, drawn with a 
pencil inside the circle, were used as controls. 

Several larvae recently hatched went to the pieces of apple, on an 
average, in 65 per cent of the chances ofifered to them ; several larvae 



l8 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

of the second instar in 50 per cent; one larva of the third instar in 
60 per cent ; and one larva of the sixth instar in 85 per cent. Several 
recently hatched larvae went to the pieces of cork in 40 per cent of 
the chances offered to them and others passed over the squares in 
30 per cent of the chances. 

These results indicate that smell and sight aid in locating objects, 
the former being the more important in perceiving odorous objects. 
Therefore, since larvae of the first instar have photopositive eyes, 
they remain in the open on apple-tree foliage and search freely for 
food, apparently not being aided by their senses until within a few 
millimeters of the food, because in these tests they wandered about 




Fig. 2. — Tracings of cliemotactic responses of recently hatched codling-moth 
larvae (see p. 17 for further explanation). A, Positive responses to small cubes 
of green apple ; B, negative responses to synthetic apple oil on small cubes of 
cork. 



aimlessly and did not perceive the pieces of apple and cork until near 
them, when they often turned and went directly to them. 

Two tests were conducted with a repellent. Pieces of cork, after 
being dipped into concentrated synthetic apple oil, were laid inside 
the circle, and within a few moments the oil had spread on the paper 
around the cork. A recently hatched larva was given 10 chances to 
touch the cork, but not once was it touched. When approaching a 
piece of cork the larva often circled around the margin of oil on 
the paper. The following day the same pieces of cork were tested 
with another recently hatched larva. To the writer the cork was 
highly scented, but it did not wet the paper. In 10 chances this larva 
was turned 12 times from its course by the repellent odor (fig. 2, B). 



NO. 10 TROPISMS OF LEPIDOPTERA — McINDOO I9 

III. GEOTAXIS 

I. REVIEW OF LITERATURE 

Frank in 1870, according to Mast (56, p. 12) , invented the term geo- 
tropism to designate the reactions of parts of plants to gravity. Loeb 
(42, p. 85 ; 43, p. 125) in 1888 claims to be the first to call attention 
to the influence of gravity on the orientation of animals. Caterpillars 
of Bomhyx neusfria were found to be geonegative, for, when confined 
in a wooden vessel with the opening at the bottom, they crept upward. 
Loeb says that " geotropism," like " heliotropism," is evident only at 
certain epochs in the life of an animal, for the result of the geotactic 
tests were not at all times consistent in the same animals. Loeb (42, 
pp. 33, 44) confined caterpillars of Euproctis chrysorrhoea in test 
tubes in a dark room and found them to be geonegative. He remarks 
that strongly negative geotaxis is no isolated phenomenon in insects 
at the hatching time and immediately after the adults have emerged 
from the pupa cases. Caterpillars of butterflies, like freshly emerged 
moths, are also geonegative, though not so markedly. Immediately 
after emerging geotaxis is much stronger than phototaxis in the butter- 
fly, but later these reactions are usually reversed. 

Mayer and Soule (59) found three species of caterpillars to be geo- 
negative. Geonegative and photopositive reactions serve to maintain 
the caterpillars of the milkweed butterfly near the upper part of their 
food and to lessen the risk of their wandering down the stem and 
starving before being able to find another milkweed. Two species of 
moth caterpillars were geonegative when about to pupate, but they 
always pupated head downward. 

Dewitz (9) remarks that geotaxis may frequently combine with 
phototaxis, thereby forcing the animals to locate themselves on the 
extreme ends of tree branches and on the crowns of trees (negative 
geotaxis), or to descend into the soil (positive geotaxis). 

Lammert (40) used an electric light beneath a special apparatus and 
found all the caterpillars tested to be geonegative with the light turned 
ofif. When the stimuli from light and gravity were simultaneously 
tested the light stimuli were the stronger. 

The latest paper known to the writer which deals with geotaxis in 
insects is by Crozier and Stier (7). Their tests were conducted in a 
ventilated dark room the temperature of which ranged from 21° to 
24° C. A weak nondirective red light was used and the observer's 
breathing currents were excluded by a screen. Tent caterpillars 
{Malacosoma mnericana) were tested and each was caused to creep 
diagonally across an inclined plane, which rested on a horizontal one. 



20 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

They call the acute angle between the two planes a and the acute one 
between the track of the caterpillar and the horizontal plane 0. The 
angle a was changed for each series of tests, and in order to have an 
average angle 6 a caterpillar was repeatedly tested, first with one side 
and then the other side downward. The results obtained are quantita- 
tively described in terms of trigonometry. The summary in part is 
about as follows : The geotactic orientation of tent caterpillars while 
creeping upon a surface inclined at angle a to the horizontal is such 
that the path makes an average angle 6 upward on the plane, of a 
magnitude proportional to log sin a. This is attributed to the fluctua- 
tion of the pull of the head region upon the lateral musculature of 
the upper side during the side-to-side swinging brought about in 
creeping. 

A review of the literature by Crozier and Stier (7) shows that 
neither the mechanical theory nor the statolith theory is sufficient to 
explain geotaxis, because neither accounts " for the quantitative rela- 
tionships between gravitational pull and the amplitude of orientation. 
There is left the appeal to the proprioceptive results of muscle ten- 
sions, already suggested to account for certain features of geotropism 
among insects and molluscs." 

2. GEOTACTIC EXPERIMENTS ON CODLING-MOTH LARVAE 

Recently hatched codling-moth larvae do not seem to be influenced 
by gravity either in the laboratory or on the foliage of apple trees. 
They avoid bright sunshine as much as possible, and if there are no 
interfering factors they crawl in all directions, as if hunting for food. 
Seventy-five larvae belonging to the fourth, fifth, and sixth instars 
were subjected to phototactic and geotactic tests in the laboratory. 
A branch of an apple tree, 30 inches long and bearing leaves, a small 
apple, and small twigs, was suspended from a chandelier. At the 
extreme top and bottom of the branch twine was wound loosely around 
the twigs to furnish a cocooning place for the larvae being tested. 
After receiving the phototactic test a larva was laid horizontally in 
one of the forks of the branch, and in such a position the light was not 
an interfering factor. The results obtained follow. 

The light reactions were found to be a crude index for judging 
the responses to gravity. Those individuals which were weakly photo- 
negative or were indififerent to light were generally not yet ready to 
make cocoons and consequently were not geopositive ; but when ready 
to spin, or later, they were nearly always strongly photonegative and 
geopositive. When larvae ready to spin were put on the branch, they 



NO. lO TROPISMS OF LEPIDOPTERA — McINDOO 21 

wandered up and down, but finally went as a rule to the bottom where 
many made cocoons in the twine, while a few dropped by threads to 
the floor. This shows that larvae of the sixth instar at cocooning 
time are strongly geopositive, but shortly before this they were usually 
indifferent to gravity. The younger instars were either indifferent or 
geonegative. Therefore, at cocooning time negative phototaxis and 
positive geotaxis are closely correlated, and when one is known the 
other can be correctly assumed. In a case of this kind why assume 
the presence of geotaxis ? Instead, why not say : " They go up owing 
to a hunger urge, and down because of a cocooning urge? " To the 
writer it seems that they " know " up from down at all times. 

While ascending the branch a few of the larvae seemed to perceive 
the small apple when within an inch of it. They stopped crawling 
and reached as far as possible in the direction of the apple. These 
and others after finally reaching it ceased to wander farther. 

IV. THIGMOTAXIS 

I. REVIEW OF LITERATURE 

Dewitz in 1885, according to Loeb (42, p. 23; 43, p. 156), first 
called attention to a contact-irritability exhibited by spermatozoa of 
a cockroach. Three years later Loeb noticed the same tropism in 
Infusoria and gave the name " stereotropism " to the peculiarity, 
which some animals have of orienting their bodies in a definite way 
toward the surfaces of solid bodies. Since this tropism in those ani- 
mals having tactile organs is brought about through the sense of touch, 
the term thigmotaxis (touch arranging) seems to be more appropriate. 

Loeb (43, p. 158; 44, p. 167) believes that positive thigmotaxis is 
second to chemotaxis in bringing about the union of the sexes. The 
holding of the female during mating is evidently a thigmotactic sense, 
and since only males and females of the same species mate, he believes 
that thigmotaxis plays a part in the selection of the proper species. 
The same author (42, pp. 22, no) found certain moths (Aviphipyra) 
to be thigmotactic because in tests they crept into crevices and in 
nature they remain in clefts in the bark of trees. He was able to 
show that light in such cases was not a factor, for the insects were 
forced to bring as much of their bodies as possible in contact with 
solid bodies. The friction and pressure produced by the solid bodies 
are considered by him to be the cause. 

Dewitz (9) says that thigmotaxis is widely distributed among the 
lower animals and that the mode of living and conduct of many species 
can be traced back to it. Insects fasten their bodies tightly to promi- 



22 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

nent objects or squeeze themselves between layers of folded dry 
goods. On these facts is based the employment of bands around 
fruit trees to catch codling-moth larvae and the caterpillars of the 
Tortricidse of the vine ; likewise the use of stones and boards in 
gardens for collecting beneath them earwigs and slugs, which can 
then be destroyed wholesale. Female grape-moths {Clysia am- 
biguella) , when laying eggs, are guided by the highly sensitive extrem- 
ity of the abdomen, and this sensitive part aids the females of many 
insects to lay eggs in fissures and folds of plants, soil, and elsewhere. 
Dewitz also believes that thigmotaxis is the chief means by which 
caterpillars and certain other insects are able to live gregarious lives. 
McCracken (47), while testing female silkworm moths, determined 
that eggs might be obtained by touching the sense hairs on the ovi- 
positor with a pencil or fibers of cotton. She says that each contact 
brings forth an egg, and under natural conditions the stimulus is 
brought about by means of the ovipositor coming in contact with the 
surface upon which the insect rests. 

2. TIIIGMOTACTIC EXPERIMENTS ON CODLING-MOTH LARVAE 

All instars of the codling moth seem to have a well-developed sense 
of touch, but the thigmotactic sense is most pronounced in the fully 
developed larvae at cocooning time. When ready to spin, these larvae 
prefer a tight and dark place in which to crawl, but if a dark one is not 
at hand they do not hesitate to spin in a well-lighted place. Years ago 
economic entomologists took advantage of this habit by placing 
" codling-moth sticks " in the rearing jars. The larvae readily spin in 
these sticks, which later may be transferred to other containers. 

Another practical application of the thigmopositive and photo- 
negative reactions of these larvae has been utilized for many years. 
When bands are placed around the trunks of apple trees to serve as a 
supplementary control method we are merely taking advantage of 
nature's laws. It therefore seems that so far as tropic responses are 
concerned the vulnerable period in the life history of codling-moth 
larvae is brought about by a change in tropisms. 

B. Tropic Receptors 

In discussions of tropisms, sensory receptors are usually implied 
as being the organs which receive the tropic stimuli, but in plants and 
the lowest invertebrates specific sense organs apparently do not exist. 
However, in the higher invertebrates and vertebrates specific sense 
organs do exist, but with regard to certain sense organs in insects 
we are still guessing at their functions and consequently cannot 
accurately connect them with any known tropism. 



NO. lO TROPISMS OF LEPIDOPTERA — McINDOO 23 

The following discussions pertain to what is generally described 
under sense organs and the senses, but no attempt is made to give 
all phases of this subject, and most of the information pertains to 
Lepidoptera. 

I. PHOTORECEPTORS 

The photoreceptors are the compound eyes and ocelli and there is 
no difficulty in connecting the compound eyes of adult moths and 
butterflies and the ocelli of their larvae with the phototactic responses 
obtained experimentally. The usual number of ocelli on an adult insect 
is three, but the sexes of the codling moth have only two each. Judging 
from sections through the eyes of both adult and larva of this moth, 
the photoreceptors seem to be normally developed, but since so much 
work already has been done on the morphology of insect eyes no 
special study was made on this subject. The reader is referred to the 
reviews by Schroder (80), Snodgrass (81), and Hering (32). 

So far as is known to the writer the only new idea on this subject 
is advanced by Lammert (40), who believes that lepidopterous larvae 
have two kinds of photoreceptors — the ocelli and others (probably 
pigment specks) in the body integument. Therefore, he believes that 
these larvae have a skin sensitive to light, which might be compared 
to that in the earthworm and other animals having photopigment 
widely distributed in the body wall. 

The results obtained by Durken (13) bear indirectly on the subject 
of body pigment used to direct the movements of larvae. He experi- 
mented five years to determine the efifects of colored lights on the 
developing stages of the cabbage butterfly. Glass panes of vivaria 
were painted white and the efifect of reflected light from green food- 
stuffs on the caterpillars was observed. Darkness produced some 
reduction of black pigment, while orange or red light produced much 
reduction of black and white pigments. Blue light caused a slight 
shifting in the direction of weaker pigmentation. Reaction to light 
occurred immediately before pupation. There was no effect previous 
to that time on the pigmentation of pupae. Pigmentation of imagoes 
was entirely unafifected by darkness or light, being absolutely inde- 
pendent of that of the pupae. 

In regard to whether sight or smell plays the greater role among 
flower-visiting insects, Clements and Long (5) present the best recent 
reviews of the literature. They conclude that phototaxis is more 
important than chemotaxis. Odors attract from a distance while sight 
attracts from nearby. Form and size of objects play a lesser part in 
attraction. 



24 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 



II. CHEMORECEPTORS 

Chemoreceptors include both olfactory and gustatory organs. Judg- 
ing from the anatomy and function of these organs in man and the 
higher animals, we are not absolutely sure that insects have true 
chemoreceptors, although their organs certainly belong to the same 
category. 

I. SO-CALLED OLFACTORY ORGANS 

(a) Antenna!. Organs. — Several investigators have studied the 
morphology of the antennal organs, but since Schenk's (79) paper 
is one of the latest and perhaps best, it will suffice for our purpose 
here. Schenk carefully studied the various types of antennal hairs 
in both sexes of the following moths: One geometrid {Fidonia 
piniaria), two bombycids (Orgyia antiqiia and Psyche unicolor), and 
one zygaenid {Ino pruni). He found five types of sense hairs as 
follows (see fig. 3 of codling moth) : (i) Pit pegs (Sensilla 
coeloconica), (2) end pegs (S. styloconica), (3) sense bristles 
(S. chaetica), (4) sense hairs (S. trichodea), and (5) pegs (S. basi- 
conica). Relative to the last named only five were found and these on 
a female of Fidonia. These five types of sense hairs were found on the 
pectinate or feathered antennae of males and on the filiform or non- 
feathered ones of the females, and not only on the shafts of both 
types of antennae but also on all the barbs of the male antennae. The 
total number of sense hairs found by Schenk in various species is 
included in table 2, which also gives the tabulated results of the present 
writer's observations on other species. 



Table 


I.— iV 


imber of so 


-called olfactory 


organs on codling-moth 


antennae 


Number 


on ma 


e antennae 




Number on female antennae 



2 


Left 
antenna 


Right 
antenna 


T 


otal 




2 


Left 
antenna 


Right 
antenna 


Total 


n! 














CO 














3 




03 




m 




tfi 


n 




w 




ui 






•0 


* 


60 




io 




60 


"O 




bo 




bo 














ID 




















.:; 








c 




0. 






G 




D- 





0. 


-o 


>» 




>. 




>. 






>. 




>, 




































►— < 


c« 


Ph 


Ui 


Oh 


m 


Ph 




tn 


s 


m 


Ph 


t/3 


fc 


I 


36 


308 


41 


319 


77 


627 


I 


46 


331 


35 


345 


81 


676 


2 


38 


268 


36 


277 


74 


545 


2 


40 


330 


40 


360 


80 


690 


3 


36 


366 


33 


373 


69 


739 


3 


36 


386 


35 


368 


71 


754 


4 


27 


296 


34 


294 


71 


590 


4 


35 


354 


35 


347 


70 


701 


5 


36 


284 


31 


244 


67 


528 


5 


47 


257 


43 


260 


90 


517 


Average f 


or rr 


lale 








Average for female 






antennae 






72 


606 




antennae 




78 


668 





















■ A few styles on each antennae do not bear end pegs. 



NO. 10 



TROPISMS OF LEPIDOPTERA — McINDOO 



25 



-J 



6 O 



c c . c - 
gEo S = S 



a> 03 



u :; : : :: 






>-, 


^ >> 


^ c. . 


, . ^ C 


oj rt ' " 


* "* oj rt 




HH P 



O r^ ^ O 

00 ^ o 






E o i^ 



000000 



m^ 








> 




> 








(D 








. . . (U - 


, 


loE-- 


, 


, 


: 




U-l 


















Tl 





















i, o 



&. , 



00000 



&- - 



000000 



V) nJ 



P^ O 



^ c p & e O 



O 'O c O o o o 



o o 

in o 



0! : 


>.o3 

c p ^ 

03 *" 11 


08 


p 


p 




" 


>, 


^>r 


>> 


u - 


(1 


■u " 


u 


(U 


> 


> 


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CO oj 



;2 03 5r 



'^0<-''~P^^Ort 
P ?, P Cl. t 

I- u a, p^ 03 o - 

03-p.- E p p - 
"! =3 § S " 

•5.2 -2 S^ 

oe&s^'B-" 



o 

a- — 

o! OJ X 



O Dh 



V-, CI. 
u _, 

u r:^ 

^ a.' 

'p ° 

P u? 



X '"=: o 



a o ^ CL 

O C 08 03 

.-H.So^: 

^P •: a 
^ p -P 1- 

JP rS y 03 



i; 'b t> j3' c 






., "= cT! t; 

•- oj *- 
C en _, o 
P t«.S;j= 

>, '^ -^rn 

!3;0 P P Q< 
u OS O rt 



HH cv| ro -t ""i>0 txOO C^ O ^ ^ <^ "1" I 



o3 

-a 



o 



1J . 

o! 

■ JS "" 
"* 5"o 

03-- p 

Oi =" 5 

.- 03 O 



OJ o3 

£ <u 
pS 
5 o 

03 I' 



1^ 03 <U -S 
"•0 oi P 


(U -O 


chic 
erii 
alid 
lire 


tl 

P 03 


>, M I- (u 


bO 


Ol <u >,„ 


O4 >. 


i:m<DhO 


>HtSJ 



•O;^ 






26 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 



The antennal organs of five male and five female codling moths 
were carefully examined by the present writer. Little or no sexual 
dift"erences were observed in the antennae or their organs. The 
antennae of both male and female are filiform and bear the same kinds 
and practically the same number of organs (tables i and 2). The 
number of segments in the antennae of males ranges from 55 to 61 
with 58 as an average ; those in the antennae of females from 59 to 
63 with 62 as an average. Each antenna bears one Johnston organ 




Fig. 3. — Antennal organs of female codling moth, No. 3. A and B, External 
views, X 125. C to G, Sections ; C to F, X 500 ; G, X 320. A, Second and third 
antennal segments ; B, two segments from middle of antenna ; C, pit peg ; D, 
style and end peg; E, sense hair and its innervation; F, non-innervated scalelike 
hair ; and G, cross section through distal end of segment near middle of antenna. 

Abbreviations: /, Johnston organ; A'', nerve; P, olfactory pore; S, style; 
Sc, sense cell; Sea, sense bristles (Sensilla chaetica) ; Sco, pit peg- (S. coelo- 
conica) ; SJi. non-innervated scalelike hair; ^'.y, end pegs (S. styloconica) ; St, 
sense hairs (S. trichodea) ; Tc, trichogenous cell; and Tr, trachea. 

(fig. 3, A, /), 2 or 3 olfactory pores (P), numerous pit pegs (fig. 3, 
B, Sco), end pegs {Ss) on styles (S), sense bristles {Sea), sense 
hairs {St), and scalelike hairs {Sh). Each of these, except the last 
named, is supposed to be a sense organ, and Freiling (23) has even 
pictured a slender scalelike hair of another moth as connected with a 
sense cell. Of these seven structures only the olfactory pores, pit pegs, 
and end pegs are supposed to be olfactory in function. 

Pit pegs may be found on all segments, except the first, second, 
and the last one or two, of codling-moth antennae. If odors can pass 



NO. lO TROPISMS OF LEPIDOPTERA McINDOO 2/ 

quickly through chitinous structures, pit pegs (fig. 3, C, Sco) would 
be excellent olfactory organs. Styles, usually terminating in end pegs, 
may be found on all segments except the first and second. A style 
(fig. 3, B, S) is nothing more than a prolongation of the distal outer 
edge of the segment and it is supposed to be innervated, but in codling- 
moth antennae it (fig. 3, D) has no nerve and consequently cannot 
be a sense organ. The writer has failed to find a drawing by any 
author showing a nerve connected with this structure. 

The antennae of 21 other species (table 2) examined by the writer 
varied much in respect to barbs, from typical filiform antennae to 
fully feathered ones. The sense organs, as a rule, were widely dis- 
tributed on both the shaft and barbs. In Argynnis cybele the pit pegs 
lie only on the club part of the antenna. Some of them are large and 
irregular in shape, and perhaps a pit bears more than one peg. In 
II of the specimens pit pegs were totally absent and in 12 no end 
pegs were observed on the comparatively few styles, and even styles 
were absent in one moth (No. 23) and in all the butterflies (Nos. 31 
to 34) examined. 

From the preceding it is evident that pore plates (S. placodea), 
common to three orders of insects (aphids, beetles, and bees and 
wasps), are totally absent in Lepidoptera, while the pegs (S. basi- 
conica) are practically wanting. These two types are the ones gen- 
erally considered as olfactory receptors in most insects. It is said that 
the end pegs and pit pegs of Lepidoptera replace the pegs and pore 
plates of other orders, but there is no proof whatever for this assump- 
tion, and furthermore it is doubtful whether the end pegs are ever 
innervated. 

Granting that the pit pegs and end pegs are the only olfactory 
organs of Lepidoptera and drawing conclusions from the observations 
of Schenk and the present writer, eight individuals (table 2, nos. i to 
4, 17, 18, 23, 24) of the 34 specimens examined cannot smell at all, 
while four other individuals (nos. 10, 19, 20, 25) have comparatively 
few end pegs as olfactory receptors. 

(b) Olfactory pores. — At the suggestion of his reviewers the 
writer (48) in 1914 called the sense organs herein discussed " olfactory 
pores." Guenther {2y) in 1901 seems to have been the first to describe 
the internal structure of these organs in Lepidoptera. He called those 
in the wings " Sinneskuppeln " and found their structure to be similar 
to that described by the present writer, although he did not see the 
pore aperture passing to the exterior. Vogel (88) made a more ex- 
tended studv of them in the wings of. many Lepidoptera. He con- 



28 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOL. 8l 



sidered them as chordotonal organs. The present writer (50, 51) 
made a thorough study of the disposition and structure of them in 
many Lepidoptera and their larvae. Priiffer {^j) has most recently 
described these pores on the wings of certain moths in connection with 
the antennal organs. 

The olfactory pores on five male and five female codling moths 
were counted. Female no. 3 was examined most carefully and conse- 
quently the greatest number of pores was found on it. In figures 4 
and 5 they are represented by black dots. The groups are numbered 
from I to 12. The isolated pores which are constant in position are 
designated by a to c, the others not being thus marked. Groups i to 6 
and pores a and h lie on the wings (fig. 4) ; groups 7 to 11 and 




Fig. 4. — Semidiagrammatic drawings of wings of female codling moth, No. 3, 
showing location of olfactor)' pores (7 to 6, a and h, and other dots), sense 
scales {Ssq^, and sense hairs {St), X 5- A, Dorsal side, and B, ventral side of 
front wing; and C, dorsal side, and D, ventral side of hind wing. Vogel (88) 
shows " Sinneskuppeln " or olfactory pores similarly located on wings of Scoria 
lineata. 



pores c and d on the legs (fig. 5, A) ; group 12 on the base of the 
labial palpus (fig. 5, E) ; and pores e (fig. 5, D) on the maxilla (one- 
half of proboscis). The number of pores in the groups follows: 
No. I, 91 ; No. 2, 70; No. 3, 52; No. 4, 12; No. 5, 129; No. 6, 52; 
No. 7, 4; No. 8, 4; No. 9. 5; No. 10, 4; No. 11, 7; and No. 12, 8. 
The total number counted on female No. 3 follows : Legs, 191 ; front 
wings, 462; hind wings, 417; proboscis, 28; labial palpi, 16; and 
second segments of antennae, 4; making 1,118 in all. The total 
number of pores on males range from 933 to 1,049, with 986 as an 
average ; and on females from 960 to 1,118, with 1,029 ^^ an average. 
Figures 6 to 8 represent the internal structure and innervation of 
the pores and sense hairs, and also the internal anatomy of the wings 
and legs where the pores are found on them. 



NO. 10 



TROPISMS OF LEPIDOPTERA McINDOO 



29 




Fig. 5. — Legs, maxilla, and labial palpus of female codling moth, No. 3, show- 
ing location and structure of sense organs on these appendages. A, Inner and 
outer surfaces of hind leg; B, same of middle leg; and C, same of front leg, 
showing location of olfactory pores (7 to //, c and d, and other dots), sense 
bristles (Sea), and sense hairs (St) ; X 5- D, Maxilla or one-half of proboscis, 
and E, labial palpus, showing location of olfactory pores (e and 12), pegs (Pg), 
sense bristles (Sea), sense hairs (St), and labial-palpus organ (Bo); X 32. 
F to M, Structure and comparative sizes of sense organs on proboscis ; X 500. 
F, External view of peg; G. looking down on its tip end; H, cross section of 
peg; and I, longitudinal section of peg. showing trichogenous cell (Tc), sense 
cell (Se), and nerve (N). J and K, External and internal structure of smallest 
sense hair. L, External view of sense bristle. M, External view of two olfactory 
pores. 



30 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 



Lepidopterous larvae can smell, but they do not have the so-called 
olfactory organs such as pegs, pore plates, pit pegs, or end pegs like 
or even similar to those of adult insects. Therefore, it is onlv reason- 




^*^«;^^' 



c 



Fig. 6. — Cross sections of wings and proboscis of Lepidoptera, showing in- 
ternal anatomy of wings and olfactory pores. A, Semidiagraminatic drawing 
from an oblique section through front wing of cabbage butterfly, showing 
groups 2, s, and 4, of pores, sense cells (Sc), nerve (A^), and trachea {Tr) ; 
X 100. B, Pores from wing of codling moth; X 500. C, A pore from proboscis 
of codling moth ; X 500. 




Fig. 7. — Schematic drawing of wing of a male Satuniia pyri L., showing 
innervation of olfactory pores (P) and other sense organs, including scattered 
pores and various types of sense hairs. The black dots represent those on the 
dorsal surface, and the circles, those on the ventral side. (Copied from 
Priiffer (77).) 



able to suppose that the pores, called olfactory by the writer, act as 
smelling organs. 

The olfactory pores of five specimens of each larval instar were 
counted. Little or no difference in position and number of the pores 



NO. 10 



TROPISMS OF LEPIDOPTERA — McINDOO 



31 



was observed in the six instars. They are found widely distributed 
(figs. 9 and 10) as isolated pores or " punctures " on the following 
parts: Head capsule, 24; maxillae, 16; mandibles, 4; labrum, 2; 
labium, 6 ; antennae, 2 ; legs, 30 ; first thoracic segment, 4 ; and anal 
prolegs, 4 ; making 92 in all. Some of those on the head capsule were 
incorrectly named in 1919 by the writer (51), but in figure 9 they are 
correctly named according to Heinrich's (31) first paper and later 
ones on this subject. 

In regard to experimental results concerning olfactory receptors, 
two papers will be briefly reviewed. The first and most important 




Fig. 8. — Semidiagrammatic drawing of an oblique section through femur, tro- 
chanter, and coxa of a silkworm moth, showing muscles (Mu), trachea (Tr), 
nerves (iV), sense cells (Sc), sense hairs (St), and groups 8, 10, and 11 of 
olfactory pores. No. 10 being shown partially from a superficial view; X 100. 

experimental work to decide the function of the olfactory pores was 
done by the writer (48) on honeybees. Of the six sources of odors 
used three were essential oils. The writer's critics have apparently 
overlooked the fact that the results obtained by using the other three 
odors are reported in such a manner that they can easily be considered 
alone. Since the odors from the oils might have been irritant, let us 
consider the other results, which, when expressed in percentages, 
clearly show how closely the percentage of pores supposed to function 
corresponds to the percentage of response obtained. On the average, a 
worker honeybee has about 2,800 olfactory pores. On the bases of 
the four wings lie 54 per cent of them; the legs possess 2^ per cent; 



32 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 




Fig. 9. — Disposition of olfactory pores or punctures on head and first thoracic 
segment of a fully grown codling-moth larva, X 20 ; A, dorsal view; and B, 
ventral view. 

Abbreviations: Frontal pore (Fa); adfrontal pore (Adfa) ; ocellar pore 
(Ob) ; anterior pore (Aa) ; posterior pores a (Pa) and b (Pb) ; lateral pore 
(La) ; ultraposterior pore (UPa) ; subocellar pores a (SOa), b (SOb), and c 
(SOc) ; genal pore (Ga) ; mandibular pores a (Mda) and b (Mdb) ; maxil- 
lary pores a (Mxa), c (Mxc), d (Mxd), c (Mxe), and / to / (Mxf-i) ; labia] 
pores a to c (Lba-c) ; labral pore (Lr) ; antennal pore (Ant) ; and thoracic 
pores a (TIa) and b (Tib). 





Fig. 10. — Disposition of olfactory pores or punctures on legs of fully grown 
codling-moth larva, X 30. A, Anterior and posterior surfaces of prothoracic 
leg, and B, dorsal and ventral surfaces of anal proleg. 

Abbreviations: Femoral pores a (Fca), b (Feb), and c (Fee); tibial pore 
(Tba) ; tarsal pore (Ta) : and anal-proleg pores a (Apa) and b (Apb). 



F 



NO. lO 



TROPISMS OF LEPIDOPTERA McINDOO 



33 



while the others He on the sting, head, and head appendages. The indi- 
viduals were allowed 60 seconds in which to respond. All of the pores 
on 31 unmutilated bees responded to the odors from honey, pollen, and 
leaves of pennyroyal in four seconds (48, pp. 283, 284) ; that is, in 
one-fifteenth of the entire maximum time allowed for the response. 
Twenty bees with their legs covered with a mixture of beeswax and 
vaseline, leaving supposedly yy per cent of the pores elsewhere to 




Fig. II. — Diagrams of Minnich's apparatus used in testing insects to olfactory 
and gustatory stimuli. A, Section of an odor chamber made of a rectangular 
museum jar, showing a butterfly, held by a wire («') and a spring clothes pin 
(j), responding with extended proboscis (/>) to apple juice (a). (After Min- 
nich.) B, Perspective view of apparatus used to show that butterflies "taste" 
with their tarsi ; a and h, two small rectangular tin pans, a containing a cheese- 
cloth pack wet with apple juice and h containing a similar cloth wet with dis- 
^tilled water; and d. a Petri dish nearly full of apple juice in which stand the 
'tin pans just beneath two openings in a wire screen {$') . The arrows, /, 3, and j, 
represent the positions in which the butterflies were tested, the position of the 
walking legs being indicated by the cross-bars. (Redrawn from Minnich's two 
figures.) 



function, responded 2. 5 times more slowly (p. 336) or gave a response 
of 83.3 per cent. Twenty-eight bees with their wings pulled off, 
leaving 46 per cent of the pores elsewhere to function, responded eight 
times more slowly (p. 335) or gave a response of 46.7 per cent. And 
finally, 20 bees with their legs covered with the beeswax-vaseline 
mixture and their wings ]nilled off, leaving supposedly only 23 per 
cent of the pores located elsewhere to function, responded 11 times 
more slowly (p. I'Sl) oi' g^ve a response of 26.7 per cent. 



34 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

Cabbage butterflies (Pontia (Picris) rapco L.) were confined by 
Minnich (63) in an odor chamber (fig. 11, A). Since they are fond 
of apple juice its odor was used to stimulate the smelling organs, and 
the responses to it were then measured by the extent to which the 
proboscis was uncoiled for the purpose of partaking of the apple 
juice, although the insects could not reach it. The antennae were 
mutilated in three ways: (i) Covered with vaseline; (2) covered 
with a mixture of paraffin and vaseline; and (3) cut ofif at the base 
with fine scissors. When the organs on only one antenna were pre- 
vented from functioning, the olfactory response was reduced only 
6 per cent ; when those on both antennae were eliminated or prevented 
from functioning, the response was reduced 58 per cent. Thus accord- 
ing to these results nearly half of the olfactory receptors must be 
located elsewhere than on the antennae. In his own words Minnich 
(P- 354) says: 

After the antennae are eliminated the animals were still 42 per cent responsive. 
Considering the variety of methods employed and the similarity of results ob- 
tained, this figure is much too large to be attributed to a failure to eliminate the 
antehnal organs completely. It must, therefore, mean that there are olfactory or- 
gans on other parts of the body as well as on the antennae. ... I cannot, there- 
fore, concur with Mclndoo in the view tliat the antennae of adult insects in gen- 
eral lack olfactory organs. Certainly, such is not the case with Pieris. Nor can 
I agree with the opposing viewpoint, that the olfactory organs of adult insects 
in general are confined to the antennae. In this respect the results on Pieris 
differ from those obtained by v. Frisch in his ingenious experiments on bees. 
The results of the present experiments show that a viewpoint intermediate be- 
tween these two is correct for Pieris, and that while the antennae constitute a 
very important, probably the most important, olfactory region of the body, they 
do not constitute the sole olfactory region. 

Regardless of the results obtained by testing insects with mutilated 
antennae, it has never seemed reasonable to the writer to suppose 
that odorous air can pass quickly through the hard and dry chitin 
covering the antennal organs. If it can, why not grant the same 
privilege to all sense organs covered with thin chitin, including all 
kinds of sense hairs and even the olfactory pores whose sense fibers, 
according to other authors, are separated from the outside air by a 
thin layer of chitin? In the higher animals the olfactory organs 
(fig. 12) are separated from the outside air by only a thin watery 
layer of mucus, and the latest results show that the free ends of the 
olfactory cilia actually come in contact with the air. Eidmann (18) 
erroneously supposed that the chitinous intima of insect intestines is 
similar to the coverings of the so-called olfactory and taste organs of 
insects. He proved chemically that aqueous solutions can pass slowly 



NO. 10 



TROPISMS OF LEPIDOPTERA — McINDOO 



35 



through the intima when the latter is wet on both sides. From this 
result he concluded that the olfactory organs of insects need no 
openings through which the nerve endings can come in contact with 
the odorous air outside. The present writer cannot see any connection 
between his findings and the chemical sense receptors of insects. 




Fig. 12. — Olfactory and gustatory organs of higher animals. A, Diagram of a 
block from olfactory mucous membrane of a kitten, showing in section and per- 
spective the following: Basal cells (b), olfactory cilia (c), nerve fibers (/), 
limiting membrane (/), olfactory cells (o), supporting cells (s), olfactory 
vesicles (v), and walls (w) of the five- and six-sided supporting cells from a 
surface view. The olfactory vesicles and cilia, which are embedded in and sup- 
ported by an outer semifluid (not shown in drawing), are the true receptors of 
smell. (Redrawn from van der Stricht's (84) photomicrographs and figure 36, 
the latter in Herrick's book (33).) B, A single taste-bud from human tongue, 
showing nerve fibers (/) indirectly innervating the surrounding epithelium (e), 
supporting cells (s), and taste cells (t), whose outer ends project into and 
sometimes beyond the pore (/>). (From Herrick (33), after Markel-Henle.) 



2. SO-CALLED TASTE ORGANS 

The so-called taste organs of Lepidoptera, according to Deegener's 
review (see Schroder (80) p. 149), consist of two round groups of 
sense hairs on the under side of the pharynx. The proboscides of 
Rhopalocera, Noctuidae, Geometridae, and Bombycidae bear at their 
tips more or less numerous peg-shaped structures of varied lengths 
and shapes in different species. In Sphingidae and Zygaenidae these 
pegs are distributed over the entire proboscides. These peculiar 



36 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8I 

Structures have been considered both tactile and gustatory in function. 
Lepidopterous larvae bear on their antennae and mouth parts variously 
shaped sense hairs, some of which have been called taste organs, some 
touch organs, and others smelling organs. 

Each maxilla on the codling moth bears about 50 pegs or about 100 
for the entire proboscis. Female No. 3 had 93 of them (fig. 5, D, Pg). 
They are always found on the distal half of the maxilla and are 
usually six-sided (fig. 5, F to H) but a few are five-sided. Each one 
(fig. 5, I) arises from the proboscis as a fluted column and terminates 
in five or six sharp pinnacles, which surround the innervated hair. 
If aqueous liquids, or odors, in order to stimulate the nerves inside 
the hairs, can pass cjuickly through the chitinous walls, we can then 
safely call them taste organs, or smelling organs ; if such a condi- 
tion is not true, they are certainly nothing more than touch receptors. 
The writer has repeatedly objected to the chemical-sense assumption, 
but believes that smell and taste in insects are inseparal)le and that 
the olfactory pores are their only receptors. Figure 12 shows the 
similarity of olfactory and gustatory organs in the higher animals and 
that the stimuli do not pass through any membrane in order to reach 
the nerves. 

Let us now consider the chemoreceptors found by Minnich on the 
tarsi of Initterflies and flies. The two species of butterflies used by 
Minnich (Co) may often be seen to alight on injured tree trunks or 
on decaying fruit in orchards, apparently for the purpose of feeding 
on the exuding sap of the tree or on the juice of the fallen fruit. In 
the presence of food it was further observed that the proboscis 
would uncoil and then coil up again in a definite manner. Minnich 
called this reaction of the proboscis a proboscis response, and later 
made use of it solely in measuring or weighing the responses of 
butterflies to various liquids. In order to determine the responses of 
the tarsal chemoreceptors, and at the same time to control the olfactory 
responses, maaiy experiments with butterflies in confinement were 
conducted by using an ingenious and specially constructed apparatus. 
Briefly stated, the apparatus consisted of a shallow dish (fig. 11, B, d) 
covered with wire screen {s), in the center of which are two small 
rectangular openings, which lie just above two small rectangular 
tin pans (a and h) inside the dish, each containing several layers 
of cheesecloth. The cheesecloth in one pan (a) was wet with apple 
juice and that in the other pan {b) with distilled water; and the 
shallow dish was also full of apple juice. A butterfly to be tested was 
held Ijy the wings with a spring clothes-j^in in position / ; that is, 



NO. TO TROPISMS OF LEPIDOPTERA McINDOO 37 

with the four feet of the middle and hind legs touching the wire 
screen and with the antennae extending directly over the cheesecloth 
wet with apple juice. Since the front legs are rudimentary and not 
used for walking, they were not considered in these tests. If the insect 
responded at all in this position, the response was a truly olfactory one. 
The hutterfly was next held in position 2 ; that is, with the head 
and antennae just ahove the cheesecloth wet with distilled water and 
with the feet of the middle legs resting on this wet cloth. If the insect 
responded at all in this position, the response was either an olfactory 
one or one hrought about by contact with the feet on the cloth, or the 
response was a combination of both olfactory and contact stimuli. 
The butterfly was finally held in position j ; that is, exactly like posi- 
tion 2 except over the cheesecloth wet with apple juice. In this position 
the insect always responded, and the responses were of the same kind 
but differed in degree from those in position 2. As an average for 
all the responses obtained in the three positions, position i gave 29 
per cent ; position 2, ij per cent ; and position j, 100 per cent ; clearly 
showing that these butterflies can distinguish apple juice from distilled 
water merely by bringing their feet in contact with these liquids. 

In other series of tests Minnich used solutions of common sugar, 
table salt, hydrochloric acid, quinine, and distilled water. In order 
to compare closely the results obtained, the first four substances were 
used on the basis of their molecular weights. Butterflies were able, 
by means of their feet alone, to distinguish the sugar solution from 
those of the hydrochloric acid and quinine, or from distilled water ; 
and the salt solution from either sugar solution or distilled water. 

Now the question naturally arises : Are there special sense organs in 
the tarsi of butterflies, which act as contact chemoreceptors ? Minnich 
gives us definite information about their function, but leaves us in 
the dark concerning their exact location and structure. Experimentally 
he located them on the four tarsi of the middle and hind legs. Each 
tarsus is five-jointed, the first joint being about as long as the other 
four combined. Alinnich believes that these organs lie in the distal 
end of the first joint, and particularly in the other four joints. He 
further believes that they are not temperature organs, touch organs, 
or organs to register the penetrating powers of liquids, but are chemi- 
cal sense organs, perhaps somewhat similar to taste organs in man. 

Excepting tactile hairs, there are no other known sense organs in 
the tarsi of butterflies, although no one apparently has looked for 
other sense organs at this place. In 1917 the present writer (50) 
reported finding olfactory pores on the legs of butterflies, but found 



38 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 81 

none on the tarsi. Recently he has more carefully examined the tarsi 
of six species of butterflies. Xo chemoreceptors were seen on the 
dark and hair}- tarsi of three species, but on most of the light colored 
ones of Pontia rapce, Papilio polyxencs, and P. troilus a row of 
supposedly olfacton.^ pores were observed on each tarsus. They are 
ver\' plain on the tarsi of the cabbage butterfly (Pontia). A few 
pores were also seen on the tarsi of the codling moth (fig. 5). If 
these pores are the only chemoreceptors on the tarsi, it is not con- 
ceivable how they can detect differences between liquids except by 
the odors which might be emitted. If the tarsi of butterflies, which 
are covered with a thick and hard chitin, contain contact chemo- 
receptors, the mouth parts of insects in general should be provided 
with such receptors. 

In other series of tests ^^linnich (61 j repeated his former ones 
and obtained similar results. According to his scheme of measurement, 
the total response of all the butterflies tested was 100 per cent to the 
sugar solution used, 84.7 per cent to the quinine solution, and 51.6 per 
cent to the salt solution. 

In his third report on this subject ^Minnich (62) says that the tarsal 
sensitivit}- of the butterflies tested to sugar solution may be as much 
as 256 times that of the human tongue. It is scarcely conceivable, 
although his carefully planned and admirably controlled experiments 
firmly convinced him that the feet of butterflies contain sense organs, 
which, when properly stimulated, are 256 times as sensitive as are 
the taste organs in our mouths. 

A fourth paper on this subject by Alinnich (65J deals with three 
species of flies. It was similarly determined that these flies can dis- 
tinguish water from paraffin oil, or from sugar solution, by use of the 
chemoreceptors in the tarsi. Chemical sense organs were also located 
in parts of the proboscis. These organs are more sensitive than those 
in the tarsi to sugar solution. ^linnich believes that all of these 
receptors serve as taste organs. Thus, according to these results, taste 
organs, at last, seem to have. been located on the mouth parts of insects. 

In regard to the so-called taste organs of insects, the writer has 
repeatedly stated that no one has demonstrated that they actually 
receive taste stimuli. Minnich ( 66 j says that the proboscis of a 
certain blowfly is clothed with hairs, some of which are long and 
curved, and that these have been proven to be taste organs by the 
following test : A fly, abundantly supplied with water but otherwise 
starved, does not extend its proboscis when these hairs are touched 
with a tiny brush wet with distilled water ; but when they are touched 



NO. 10 TROPISMS OF LEPIDOPTERA — McINDOO 39 

with another brush wet with sugar sohition the proboscis is quickly- 
extended. These hairs are so sensitive that a single one, when touched, 
may produce the response. According to the accepted definition of 
taste, these hairs are true taste organs provided the sugar solution 
must actually touch them; if only a close proximity is required, then 
the sense of smell is involved. When asked this question, Minnich 
was not sure that he had totally eliminated smell. If these hairs are 
true taste organs, the present writer cannot understand how an aque- 
ous solution can pass instantaneously through their walls in order to 
stimulate the nerves inside. 

III. AUDIRECEPTORS 

The common belief that insects can hear is based on three facts : 
(i) Many of the experimental results obtained indicate that they 
can perceive sound stimuli, although perhaps they do not hear as we 
do; (2) many have special sound-producing organs; and (3) many 
have so-called auditory organs. 

The first report on the auditory sense of Lepidoptera was probably 
made in 1876. Since that date much has been published, but critics 
are still inclined to doubt whether any insect can really hear. 
Turner (86) and Turner and Schwarz (87) in 1914 produced good 
experimental evidence to show that Catocala and giant silkworm moths 
really hear. They used an adjustable organ pipe, an adjustable pitch 
pipe, and a Galton whistle. Their field experiments demonstrated that 
most of the moths tested can hear high-pitched notes, but usually 
low-pitched ones did not produce responses. They believe that re- 
sponses of moths to sounds are expressions of emotion and that a 
response depends upon whether the sound has a life significance to the 
insect tested. 

For many years it has been known that both adult and larval Lepi- 
doptera are able to produce sounds and some of the sound-producing 
organs have been described. For example, the death's-head moths 
(Acherontia) make shrill chirping sounds, probably by forcing air 
through certain parts of the anatomy. Their larvae produce " crack- 
ling " notes. A hissing noise is made by several species of Vanessa and 
more pronounced sounds are produced by other Lepidoptera. Stridu- 
lating organs on the wings have been described by several, including 
Hampson (28) and Jordan (35). In certain Agaristidae and Geo- 
metridae the sound is made by pressing the tarsi against the ribbed 
areas on the wings. This subject is reviewed by Schroder (80, pp. 61- 
74) and Hering (32, pp. 190-193). 



40 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 




Fig. 13. — So-called auditory organs of Lepidoptera. A, Diagram from longi- 
tudinal section through portions of thorax and abdomen of a noctuid moth, 
showing following parts of tympanic organ: Gu Tympanic pit at whose base 
is found the drum head (T) and G2, tympanic cavity with drum head (GT). 
The two tympanic cavities are very deep, dorsolateral invaginations of the in- 
tegument which touch one another at the median line where they form a com- 
mon division wall (MS). In Catocala they do not touch one another. Tb, 
Tympanic chamber; A'^, tympanic nerve; Ch, chordotonal bundle; L, ligament 
of same; Td, tympanic cover; and Lni, chitinous lamella, separating the true 
drum head (T) from the other drum head (GT) and serving for the insertion 
of the chordotonal bundle (after Egger (17)). B, Chordotonal bundle of a 
notodontid (Phalcra buccphala L.), showing drum head (T), ligament (L) of 
chordotonal bundle, tympanic nerve (A''), sense cell (Sc), sense rod or " Stift " 
(Sr), and cap cell (Cc), (after Egger (15))- C, Portion of drawing from 
longitudinal section through base of front wing of Lycacna icarus, showing 
chordotonal organ (Ch) and " Sinncskuppeln " (P) or olfactory pores. D, 
Single chordotonal element from front wing of Chimabacchc fac/, showing sense 
cell (Sc), vacuole (Va), enveloping cell (Ec), axial fiber (-^.r), sense rod 
(Sr), and cap cell (Cc). C and D after Vogel (89). 



NO. lO TROPISMS OF LEPIDOPTERA McINDOO 4I 

I. TYMPANIC ORGANS 

According to Eltringham's (19) review, tympanic organs in Lepi- 
doptera were first recorded in 1889 in Uraniidae. Since that date 
several other writers have described these sense organs in Lepidoptera, 
which are similar in strncture and probably in function to those in 
Orthoptera. As Eggers (15) has presented the most comprehensive 
paper on this subject, his results are here briefly summarized. In all 
he examined 150 species of moths and 5 species of butterflies, repre- 
senting over 40 families. No tympanic organs were found in 39 
species of moths and in the five species of butterflies. They were 
found, however, in various stages of development in the thorax of 
95 species and in the abdomen of 16 species of the moths. Thus 
71.6 per cent of all had tympanic organs. Judging from this study 
butterflies and many moths, including Sphingidae, Saturniidae, and 
Bombycidae, apparently have no tympanic organs, and none was found 
in the codling moth by the present writer. The location and structure 
of the organs found by Eggers are represented by figure 13, A and B. 

Eggers (17) next determined that the tympanic organs in noctuid 
moths are auditory in function. Noctuids, when in an excited condi- 
tion, reacted to difl:'erent sounds by flying or by raising the wings. 
They were tested under glass funnels to loud, sharp sounds such as 
those made by hand clapping, and to soft ones, as the twisting of a 
glass stopper in a bottle. When the drum heads (fig. 13, A, T) of 
both of the tympanic organs were destroyed the moths no longer 
reacted to sounds. When the drum head in one organ was destroyed 
the moths reacted to sounds in seven-tenths of the cases by flying. 
Moths with intact tympanic organs but with wings removed reacted 
to sounds in one-half the cases by running; in the other cases, by 
quick movements of the leg or antennae. Moths with intact tympanic 
organs but with antennae removed, reacted to sounds by flying. He 
concluded that these organs are sound receptors, analogous to the ears 
of mammals. 

2. CHORDOTONAL ORGANS 

The name chordotonal means a chord, or string, which is sensitive 
to tones. Graber (26) in 1882 presented the first comprehensive paper 
on the chordotonal organs, and much of our present information on 
this subject is based solely on his report. He apparently found these 
organs in a wide range of adult and larval insects, but he evidently 
included other sense organs too. Excluding the olfactory pores on 
insect wings, he did not find chordotonal organs in adult Lepidoptera, 



42 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL, 8l 

but found them in the larvae of the codHng moth and of Tortrix 
scrophulariana. 

According to the review by Turner and Schwarz (87), chordotonal 
organs are not found in Myriapoda and Arachnida. They are found, 
however, in some insects which do not need a sense of hearing. They 
are well developed in caterpillars, even in those of Tortricidae, which 
spend their entire larval period inside of fruit. Eggers (16) remarks 
that chordotonal organs have been found in the first antennal segment 
(scape) of Apterygota, Orthoptera, and Hemiptera; in the second 
antennal segment (pedicel) of Neuroptera ; and in the third antennal 
segment (first segment of funiculus) of Orthoptera. Some of these 
are called the Johnston organs, which are discussed later. 

In the bases of lepidopterous wings Vogel (89) distinguished two 
types of sense receptors — chordotonal organs (fig. 13, C, Ch) and 
" Sinneskuppeln " (P) or olfactory pores. The former (fig. 13, D) 
seem to be true chordotonal organs, but the present writer did not 
see them in codling-moth wings or in those of other Lepidoptera. 

Nothing definite is known about the function of the chordotonal 
organs, but they are usually considered as sound receptors. Since 
most of the movements of insects result in rhythms, as pointed out 
by Eggers, Snodgrass (81) suggests that these organs be regarded 
as rhythmometers. 

3. JOHNSTON ORGANS 

Tympanic organs, chordotonal organs, and Johnston organs are all 
chordotonal organs, because each sense element is chordlike in shape 
and has a sense rod, scolopala, or " Stiff " according to the Germans. 
A tympanic organ is quite dififerent from the other two types owing 
to the presence of a drum head or tympanum, A chordontonal organ 
and a Johnston organ usually differ little; if found in the pedicel, 
it is generally considered the latter ; if found elsewhere, it is called the 
former ; but in many insects both occur in the pedicel, A good review 
on this subject is by Snodgrass (81). The paper by Eggers (16) is 
the most comprehensive on this subject. He studied the Johnston 
organs in the pedicels of most of the insect orders and concluded that 
they are true '' Stift " organs and are common to all insects, including 
Apterygota. In regard to the antennae of larvae he found them in 
hemimetabolous forms, but absent in holometabolous ones. Therefore, 
caterpillars do not have the Johnston organs. 

In both sexes of the codling moth the present writer found the 
Johnston organs (fig. 14) to be highly developed, and the sense rod 



NO. 10 



TROPISMS OF LEPIDOPTERA — McINDOO 



43 



or " Stift " (Sr) is only slightly different from that pictured in the 
Lepidoptera examined by Eggers. The writer also saw external marks 
of these organs in many other Lepidoptera. 

Eggers informs us that their structure is not correlated with that 
of the tympanic organs. Formerly they were assumed to be auditory 
in function, but more recently they have been called muscular receptors 



.S^cc'^y Sefm^ff 




Fig. 14. — Johnston organs of codling moth, X 500. A, Semidiagrammatic 
drawing, showing one olfactory pore (f) and Johnston organ whose distal end 
is attached to articular membrane (Am). This membrane consists of three con- 
centric bands of chitin; two tiiin and flexible ones (represented by lines) and a 
thick, rigid, and much wider one (soHd black) between them. Therefore, it 
sHghtly resembles a drum head and apparently may be vibrated by jars or by 
movements of the flagellum. B, Detailed structure of a single chordotonal ele- 
ment drawn from two sections. All parts, except the nuclei of the enveloping 
cell (Ec) and cap cell (Cc), were distinctly seen. Other authors have seen these 
nuclei in other Lepidoptera. The terminal fiber (Tf) of each element is 
fastened at the bottom of a pit (p) which usually lies in the rigid and thick 
band of the articular membrane. The other abbreviations are the same as those 
in figure 13, D. 



or statical-dynamic organs to register the movements of the antennae. 
Eggers believes that they probably perceive the movements of the 
articular membrane to which they were attached. These movements 
are caused by the antennae being used as tactile organs, or by the wind 
vibrating these appendages. In the males of Culicidae and Chirono- 
midae, however, they may be special auditory organs. The present 
writer (52) in 1922 studied the Johnston organs in the honey-bee in 



44 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

which the articular membrane, to which the sense fibers are attached, 
resembles the head of a drum. It was then suggested that these organs 
might receive stimuli from gusts of wind, weak air currents, or from 
jars, but the most reasonable function considered was that they regis- 
rered the movements of the flagellum. 

4. AUDITORY HAIRS 

Years ago there was a controversy as to whether spiders possessed 
auditory hairs. When a. dead spider was put under a microscope and 
certain musical tones were produced, some of the hairs on the spider 
were seen to vibrate. This observation alone is no more proof for an 
auditory sense in spiders than to say that one stringed musical instru- 
ment can hear another if a certain cord of the first vibrates when a 
cord of the second is struck. Recently Minnich (64) has revived the 
subject of auditory hairs and shows definitely that certain hairs are the 
sound recej)tors in larvae of the mourning-cloak butterfly. When a 
test such as was given with a dead spider was repeated, no hairs on 
a freshly killed larva were seen to respond to the same tones to which 
larvae normally react. 

Minnich's review shows that certain caterpillars in all instars react 
to a variety of sounds, including those made by slamming a door, 
clapping the hands, the human voice, a violin, and a shrill whistle, but 
the earlier observers did not locate the sound receptors. Minnich used 
sounds produced by the human voice, piano, organ, violin, dish pan, 
Galton whistle, tone modulator, and tuning forks. The larvae re- 
sponded to all of these, except the whistle and modulator, usually b}' 
throwing the anterior third of the body dorsally or dorsolaterally. The 
extent of the response to sounds varied with the intensity of the tone. 
For full-grown larvae the upper limit of response was probably not 
far from C" (1,024 complete vibrations per second). Responses were 
obtained from ^2 to 1,024 vibrations per second. Responses to sounds 
increased greatly with age, being least in the first and greatest in the 
last two instars. The responsiveness was correlated with the numlDcr 
of body hairs, which were fewest on the first instar and most abundant 
on the last instar. Responses to ordinary mechanical stimulation de- 
creased with age, being greatest in the first and least in the last instar. 
Headless larvae and fragments of bodies responded to sounds, but the 
auditory hairs were found to lie chiefly on the anterior two-thirds of 
the insect. These hairs are probably some of the ordinary tactile ones 
(Sensilla trichodea) studied by Hilton (34), who claimed that most of 
the body hairs of caterpillars are innervated. Minnich believes that the 



NO. lO TROPISMS OF LEPIDOPTERA McINDOO 45 

body hairs act as sound receptors for three reasons : ( i ) Singeing 
the hairs greatly reduced or abolished the responses ; (2) hairs bearing 
water droplets or flour did not respond; and (3) during the molting 
periods when the hairs were disconnected with their nerves there was 
little or no response. 

Abbott (2) observed that normal Datana larvae gave definite re- 
sponses to air currents and sudden jars, but to only two notes — C" 
(512 vibrations) and F sharp (728 vibrations) — by elevating the 
anterior and posterior parts of the body. These notes were made by 
using a closed pipe with a movable plunger, a piano, and a mandolin. 
He assured us that he believed the normal larvae actually responded to 
the foregoing musical instruments for four reasons : ( i ) They were 
protected from air currents when tested; (2) they were several feet 
from the instruments; (3) vil)rations from the substratum were 
eliminated ; and (4) no responses were observed when the body hairs 
were covered with water or shellac, or when the body surface was 
anaesthetized with a 2 per cent solution of procain. Since these 
caterpillars responded to only two notes, which are not experienced in 
nature. Abbott believed that these responses were not adaptive, but 
perhaps secondary, resulting from an " adaptation of certain organs 
to more significant stimuli." 

IV. THIGMORECEPTORS 

I. TACTILE ORGANS 

It seems that no one has made a thorough stud)- of the tactile organs 
of Lepidoptera, but those in certain beetles have been carefully studied. 
The writer (53) found tactile hairs on the cotton boU weevil as fol- 
lows : Sense hairs (Sensilla trichodea). on the head capsule, antennae, 
mouth parts, thorax, legs, wings, and abdomen ; sense bristles 
(S. chaetica), on nearly the same parts; and sense pegs (S. basi- 
conica), on the head capsule, mouth parts, and genitalia. Besides these 
three types Lepidoptera have a fourth, the sense scales (S. squami- 
formia) ; however, it seems that only the small, narrow scales are 
innervated, while the large, broad ones (fig. 3, B, Sh) have no nerve 
connection. If the end pegs (S. styloconica) are really innervated, 
we should add a fifth type of tactile organs. 

Sense scales on the wings of Lepidoptera have been described b>- 
Guenther (27), Freiling (23), Vogel (88), and Priiflfer {yy). Vogel 
states that innervated scales are found on the wings of all Lepidoptera, 
occurring on both sides, mostly on the veins and particularly on the 
marginal ones, but they may be found also on the basal parts of the 



46 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

wings. Quenther believes that the sense scales are wind tactile organs, 
used in orientation. With the aid of them Freiling believes that night- 
flying Lepidoptera in their rapid movements are able to avoid obstacles. 
In regard to tactile hairs on the codling moth, all parts of the 
integument were not searched for them and in most cases where found 
they were identified from external appearances. Most of the tactile 
hairs on the wings seem to be ordinary sense hairs (fig. 4, A, St), but 
a few sense scales (Ssq) were seen. On the legs, maxillae, and labial 
palpi sense hairs (fig. 5, A and D, St) and sense bristles (Sea) are 
more or less numerous. On the antennae are found numerous sense 
hairs (fig. 3, St), sense bristles (Sea), and end pegs (Ss). The large 
non-innervated scales (fig. 3, G, SJi) overlap one another like shingles 
on a roof and on some segments they cover nearly all the sense organs. 
The peculiarly shaped pegs found on the maxillae (fig. 5, D, Pg and I) 
are also to be classified as tactile organs. Some of the tactile hairs 
on the antennae and mouth parts of codling-moth larvae are shown in 
figures 9 and 10. 

V. GEORECEPTORS 
I. BALANCING ORGANS 

When an animal responds to gravity a special static or balancing 
organ is not necessarily involved, but such organs are known in four 
Phyla — Ccelenterata, Mollusca, Arthropoda, and Vertebrata. Semi- 
circular canals occur in the vertebrates, while otocysts or statocysts 
are found in certain medusae, molluscs, and crustaceans. A statocyst 
may be an open or closed cavity, lined with sense hairs. In the center 
of the cavity may be one or more concretions of carbonate or phosphate 
of lime, called otoliths or statoliths. In the shrimp a statocyst is found 
in a segment of the claw. It is an open sac in which the shrimp 
places grains of sand. As the animal moves about in all directions, 
the grains of sand fall against the sense hairs thus enabling the shrimp 
to keep its equilibrium. A statocyst, therefore, is nothing more than a 
special touch organ, and the same may be said about the semicircular 
canals in which the liquid in them takes the place of the statoliths. 
A good review on this subject is by Dahlgren and Kepner (8, pp. 207- 

215)- 

Insects so far as we know do not have organs similar in function 
to the semicircular canals and statocysts ; nevertheless, they certainly 
have great balancing powers. The only case in which such organs 
have been surmised is in the Diptera. The so-called balancers or 
halteres were formerly considered organs of equilibrium, but flies can 
fly just as well without them. 



NO. 10 



TROPISMS OF LEPIDOPTERA — McINDOO 



47 



Vom Rath (78) first described a flask-shaped structure in the distal 
segment of the labial palpus of the cabbage butterfly. The structure 
is lined with innervated hairs which he considered olfactory in func- 
tion. He imagined this structure to be a special olfactory organ for 
detecting the presence of food. This structure, whose shape varies 
considerably, seems to be common to all Lepidoptera. It was seen in 
practically all of the specimens examined by the present writer. It is 
present in the labial palpi (fig. 5, E, Bo) of both sexes of the codling 
moth, in which it is sac-shaped, opening to the exterior by a wide mouth 
(fig. 15, A). The innervated hairs (fig. 15, B, Hr), instead of being 
narrow and hollow as figured by vom Rath, are wide, heavy, and club- 




FiG. 15. — Sense organ in labial palpus of codling moth. It is probably a static 
or balancing receptor. A, Diagram of a longitudinal section through terminal 
segment, showing organ made up of sense hairs (Hr), sense cells (Sc), and a 
large nerve (A'') ; B, drawing from an oblique section, showing same parts, 
X750. 

shaped. They certainly cannot be olfactory in function. Since their 
slender bases arise from very delicate chitin, their clubbed ends prob- 
ably swing in various directions as the insect moves about. This organ 
reminds the writer of the statocysts, especially those of the shrimp and 
crayfish, and it probably has a similar function. If it does not contain 
statoliths, the hairs may operate sufficiently without the use of them. 

VI. OTHER RECEPTORS 
Among the general sensations of Lepidoptera might be mentioned 
those of temperature, humidity, direction, hunger, fear, and pain, but 
they are probably not connected with special sense receptors. 



48 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 81 

Much experimental work on various temperatures, particularly as 
control measures, has been done on Lepicloptera, but little or none of 
it can be discussed from the tropic point of view. The sense of 
temperature is probably well developed, although in insects, as in our- 
selves, there are probably no special thermoreceptors. The subhypo- 
dermal nerve plexus, if present in adult Lepidoptera as found in 
caterpillars by Hilton (34), could easily perform this function. 
Humidity, which is closely related to temperature, also has much to 
do with the behavior of Lepidoptera. Hering (32, p. 201) remarked 
that butterflies have a barometric sense, because sultriness and low 
barometric pressure have a characteristic effect on both the adults and 
larvae. He imagined that some of the antennal organs are the recep- 
tors. Guenther (2/) hazarded the opinion that the " Sinneskuppeln " 
(olfactory pores) were barometric receptors. 

Prijffer (y/) states that his results and those of Patijaud demon- 
strate that female moths cannot lure the males from long distances, 
in spite of evidence shown years ago by Forel, Fabre, and others. 
He says that the females of Satuniia pyri L., as an example, can 
attract the males from a distance of not over 50 meters. Noel (68) 
concluded that neither sight nor smell is sufficient to explain the attrac- 
tion from long distances. As a hypothesis, he suggested that certain 
insects emit special waves or rays, resembling X-rays, or the Hertzian 
waves, or even the N-rays of Dr. Blondlot. He firmly believed that 
these rays, which have not yet been isolated or verified, really exist 
and that they are used in distant communication. It has also been 
suggested that the bushy antennae of certain moths support this theory. 

C. Scent-Producing Organs 

The study of scent-producing organs follows as a corollary to that 
of tropisms and tropic receptors. Since chemotaxis is such an impor- 
tant means of communication among insects, it is probably true that 
all insects have structures for producing odors. In fact these structures 
have already been described in numerous species belonging to most 
of the insect orders. 

Several years ago the writer (49) reviewed the literature on this 
subject. A brief summary of that review concerning Lepidoptera 
follows : Scent scales on the wings constitute the almost universal 
type of scent-producing organs in male butterflies. Clark (4) has 
recently reviewed this subject and added much new information. A 
pair of invaginated sacs located at the ventro-posterior end of the 
abdomen has been found in certain male butterflies. These sacs are 



m 



NO. lO TROPISMS OF LEPIDOPTER^V McINDOO 49 

partially lined with scent hairs at the hases of which lie unicellular 
glands. In a certain female hutterfly the same organ is present, but 
there is also a circle of scalelike scent hairs around the anus. In 
another female butterfly there is a single invaginated sac, similarly 
located. In the females of the maracuja butterflies, a pair of styled 
knobs at the posterior end of the abdomen serves as a scent-producing 
organ. 

The most common type of scent organ in male moths is a tuft of 
scent hairs on the tibiae of the third pair of legs. Occasionally there 
are also tufts of hair on the tibiae of the first and second pairs of legs. 
Another common type in certain male moths is a pair of tufts of 
scalelike scent hairs at the base of the abdomen. In the males of other 
moths a pair of invaginated sacs, lined with scent hairs, lies in the 
ventro-posterior end of the abdomen. In the females of certain moths 
a paired tuft of scent hairs lies near the anus. The scent-producing 
organ of the female silkworm moth {Bombyx mori) is the most highly 
developed of any found in a female lepidopteron. This organ is a 
pair of invaginated and greatly folded sacs in the posterior end of 
the abdomen. The female attracts the male by evaginating and turning 
these sacs inside out, thus fully exposing the inside which is moist 
with an aromatic substance. In all cases where scent hairs are present, 
each hair is connected with a unicellular gland. 

The only scent-producing organ found by the writer in codling 
moths is a pair of invaginated sacs (fig. i6, A) in the ventro-posterior 
end of the abdomens of males. The mouth of the sac seems to be a 
long slit along the ventral median line. Muscles (Mii), which nearly 
surround the sac, apparently change the slit into a wide opening, 
forcing the 90 scent hairs (//) to the exterior between two abdominal 
segments. Each hair (fig. 16, B) is long and its base is connected with 
a single gland cell (Gc) at the anterior end of the sac. In cross section 
(fig. 16, C) the hairs are round or oblong, are transparent, and have 
a spongy texture. The outer wall is rough and a pore (/>) can 
occasionally be seen in it. When greatly magnified the gland cells 
(fig. 16, D) are large and typical for scent-producing organs. Judg- 
ing from this structure alone male codling moths attract the females 
by means of emitting odors from an aromatic substance which passes 
through pores in the scent hairs to the exterior. 

No one seems to have described a scent-producing organ like the 
one in the codling moth, but Freiling (23) has described a similar 
one in a male butterfly (Daiiais scptcntrionalis). In this case the 
mouths of the paired sacs lie on either side of the anus. Most of the 



50 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 



scent hairs are attached to the anterior portion of the sac. When the 
sac is evag'inated and the tuft of hair is expanded, this organ resembles 
a cyHndrical fan whose contents are turned inside out to form the 
circular part of the fan. The scent hairs are filled with a matrix 
substance and the secretion passes through tiny pores in the walls of 
the hairs to the exterior. 

Jordan (36) discovered in a number of Notodontidae a flap, which 
he called a cteniophore. It is movable and partlv covers a cavity in 




Fk;. 16. — Scent-producing organ of a male codling moth. A, Cross section 
through tip end of abdomen, showing location of a pair of invaginated sacs, which 
are evaginated by muscles (Mti) thereby exposing the hairs (H) to the ex- 
terior, X 53 ; B, longitudinal section through tip end of abdomen, showing 
muscles (Mu) attached to invaginated sac filled with scent hairs (H) to which 
are attached unicellular scent glands (Gc), X 53 ; C, cross section of scent hairs, 
showing their spongy texture and pores (p) in outer wall, X 500; D, longitudinal 
section through bases of two scent hairs (H) and their gland cells (Gc), X 500. 

the pleurum of the fourth abdominal segment. It is a special male 
apparatus developed in connection with scent organs. He believed 
that the hind tibia and hind wing were rubbed across the cteniophore 
to receive an odorous substance, probably from glands in the cavity. 
A remarkable combination of tympanic organ and cteniophore was 
earlier discovered by Jordan and more recently pictured by Hering 
(32, p. 195). In codling moths, a projection, probably a cteniophore, 
lies on either side of the abdomen of the males, but no cavity is present. 



no. lo tropisms of lepidoptera — mcindoo 5i 

Summary and Discussion 

In order to throw light on the biology of the codling moth, a 
thorough investigation of the tropisms of this insect was begun in the 
spring of 1927. Definite results were obtained only by using the larvae. 
In all 154 larvae, belonging to the two broods at Silver Spring, Md., 
were tested individually in the laboratory under various conditions. 
In bright light, although not direct sunshine, larvae of the first instar 
were weakly photopositive. Certain tests indicated that objects are 
perceived and located by the senses of smell and sight, and by mere 
' chance. Chance alone seemed to be only 30 per cent efficient ; sight 
and chance combined, 40 per cent efficient ; whereas smell, sight, and 
chance combined were 65 per cent effective. Therefore, since larvae of 
the first instar have photopositive eyes, they remain in the open on 
apple-tree foliage and search freely for food, apparently not being 
aided by their senses until within a few millimeters of the food. The 
larvae were found to be easily repelled by odorous substances, but 
attracted with difficulty. 

Larvae of the second, third, and fourth instars were weakly photo- 
positive to weak light, but indifferent to strong light. Larvae of the 
fifth instar sometimes acted indifferently to light but generally were 
weakly photonegative. Larvae of the sixth instar were either weakly 
or strongly photonegative, the degree depending on their age ; and 
those with blackened ocelli did not respond to light. At cocooning time 
the larvae were strongly photonegative, geopositive, and thigmoposi- 
tive, whereas during their earlier instars they either behaved indiffer- 
ently to light, gravity, and touch, or were photopositive, geonegative, 
and thigmonegative. Consequently, when the larvae are ready to spin 
cocoons they avoid bright light as much as possible, usually move 
toward the ground and hunt for dark and tight places in which to 
pupate. When bands are placed around the trunks of apple trees to 
serve as a supplementary control method, we are merely taking ad- 
vantage of nature's laws. It therefore seems that so far as tropic 
responses are concerned the vulnerable period in the life history of 
codling-moth larvae is brought about by a change in tropisms. 

It is well known that certain varieties of apples are more susceptible 
to codling moth injury than are other varieties ; why, no one knows, 
but several factors, including thickness, toughness, and waxiness of 
apple peel, and the odorousness and acidity of apples, might be con- 
sidered. Owing to one or more of these factors the larvae probably 
gain entrance to the more susceptible varieties with less difficulty ; or 
the female moths perhaps distinguish differences between apple trees. 



52 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

and if so, they probably lay more eggs on the preferred varieties. 
No attempt was made in the present investigation to determine which 
was true, but it is certain that the larvae can distinguish apples by 
smell and touch, and the moths are certainly guided by tropic stimuli 
to the proper places for depositing eggs. A study of this kind raises 
more cjuestions than it answers, yet there is no other way to make 
progress. Not l)eing able to throw light on this question, a thorough 
study of the morphology of the sense organs of the codling moth and 
its larvae was made, hoping that a little light might finally be had. 

Since the moths are nocturnal fliers, their eyes cannot be their 
chief sensory receptors for locating the proper host plant. As already 
stated, the eyes of the larvae change slowly from photopositive ones 
in the first instar to strongly photonegative eyes in the last instar. 
This change may be caused by a migration of pigment, as found in 
certain other larvae, and it seems to be in harmony with the habits of 
these larvae, which spend most of their time inside of fruit. Before 
entering apples, photopositive eyes are needed ; but after emerging for 
the purpose of pupating, photonegative eyes are required. 

Two kinds of smelling organs — certain hairs on the antennae, and 
the pores, called olfactory by the writer — are fully described. It seems 
doubtful whether these hairs, called pit pegs and end pegs, can serve 
as olfactory organs owing to their hard covering of chitin. Granting 
that these hairs are the only olfactory receptors of Lepidoptera, eight 
of the 34 individuals discussed in table 2 cannot smell at all, while 
four others can smell only slightly. The codling moth, however, has 
a good supply of them. Larvae do not have these so-called olfactory 
organs, yet they can smell. The olfactory pores are common to both 
adult Lepidoptera and their larvae. In the adult they are found on the 
wings, legs, mouth parts, and second segment of the antennae. In 
the larvae they occur on the head, mouth parts, antennae, legs, first 
thoracic segment, and anal prolegs. 

There are supposedly two types of taste organs. The first type 
consists of certain hairs on the mouth parts, but since these are covered 
with hard chitin the writer does not believe that aqueous liquids can 
pass quickly through them in order to stimulate the nerves inside. The 
second type is Minnich's tarsal chemoreceptors, which, when properly 
stimulated, are 256 times as sensitive as are the taste organs in the 
human mouth. We know nothing about the structure of these recep- 
tors, and the present writer so far has found only two kinds of sense 
organs — sense hairs and olfactory pores — in the tarsi of insects. 



NO. 10 TROPISMS OF LEPIDOPTERA — McINDOO 53 

We now have good evidence that both adult Lepidoptera and their 
larvae can hear, although probably not as we do. Four kinds of so- 
called auditory organs have been described. They are tympanic organs, 
chordotonal organs, Johnston organs, and auditory hairs. The first 
three have been found in adult Lepidoptera, while the second and 
fourth occur in caterpillars. Of these four the writer found only the 
Johnston organs in the adult codling moth, but Graber in 1882 saw 
chordotonal organs in the codling-moth larva. It has been shown 
experimentally that tympanic organs and auditory hairs are affected 
by sound waves, but we know nothing definite about the functions of 
the chordotonal and Johnston organs. 

Other special sensory receptors of the codling moth include certain 
innervated hairs serviceable as tactile organs and a well-developed 
structure in the labial palpus. The latter might function as a balancing 
organ. The general senses to temperature, humidity, etc., are not 
supposedly connected with special sense organs, although these senses 
seem to be well developed in Lepidoptera. In connection with the 
olfactory organs the scent-producing organs were studied. The only 
one found in the codling moth is a pair of invaginated sacs in the 
abdomen of males ; thus it seems that the males attract the females 
and not the reverse. 

In conclusion it has been shown that considerable information is 
now available on the tropisms and sense organs of Lepidoptera, but 
there is much yet to be learned, and the problem should be attacked 
from all angles, using the best equipment obtainable. A recent review 
by Kennedy (38) helps to clarify certain phases of insect behavior. 
He remarks that while sensitivity is a function of the nervous system, 
it is conditioned by other structural features, such as small size and 
chitinous exoskeleton. Hase (29) has recently described his physio- 
logical laboratory and equipment at Berlin-Dahlem, which should be 
emulated by other scientists doing similar work. Much of his appa- 
ratus is used for testing the tropisms of insects. 

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1922. The auditory sense of the honey-bee. Journ. Comp. Neur. 34: 
173-199, 26 figs. 



1927. Smell and taste and their applications. Sci. Monthly, Dec. 25:481- 
503, 14 figs. 



1926. Senses of the cotton boll weevil — An attempt to explain how 
plants attract insects by smell. Journ. Agr. Research 33: 
1095-1141, 16 figs. 

(54) 

(55) 

1928. Responses of insects to smell and taste and their value in control. 
Journ. Econ. Ent. 21:903-913. 

(56) Mast, S. O. 

191 1. Light and the behavior of organisms. New York, 410 pp.. illus. 

(57) 

1915. What are tropisms? Arch. f. Entw. Mech. der Organismen 41: 
251-263. 

(58) M.^VER, A. G. 

1900. On the mating instinct in moths. Psyche 9:15-20. 

(59) AND SouLE, C. G. 

1906. Some reactions of caterpillars and moths. Journ. Exp. Zool. 3: 
415-433. 

(60) MiNNICH, D. E. 

1921. An experimental study of the tarsal chemoreceptors of two 

nymphalid butterflies. Journ. Exp. Zool. 33:173-203, 6 figs. 

(61) 

1922. The chemical sensitivity of the tarsi of the red admiral butterfly. 

Pyrameis afalaiita Linn. Journ. Exp. Zool. 35:57-81, 3 figs. 

(62) 

1922. A quantitative study of tarsal sensitivity to solutions of sac- 
charose, in the red admiral butterfly, Pyrameis atalanta Linn. 
Journ. Exp. Zool. 36:445-457, i fig- 

(63) 

1924. The olfactory sense of the cabbage butterfly, Pieris rapac Linn., 

an experimental study. Journ. Exp. Zool. 39:339-356, i fig- 

(64) 

1925. The reactions of the larvae of Vanessa antiopa Linn, to sounds. 

Journ. Exp. Zool. 42:443-469, 2 figs. 

(65) 

1926. The chemical sensitivity of the tarsi of certain muscid flies. Biol. 

Bull. Mar. Biol. Lab. Woods Hole 51:166-178, 2 figs. 



\ 



58 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8 1 

(66) MiNNICH, D. E. 

1926. The organs of taste on the proboscis of the blowfly, Phormia 

regina Meigen. Anat. Record 34:126. 
(6y) Morgan, A. C, and Lyon, S. C. 

1928. Notes on amyl salicylate as an attrahent to the tobacco hornworm 
moth. Journ. Econ. Ent. 21:189-191. 

(68) Noel, P. 

1915. L'attirance des males par les femelles. Bull. Trim. Lab. Ent. 
Agr., Seine-Inferieure, Rouen, 16 pp. 

(69) Parker, G. H. 

1903. The phototropism of the mourning-cloak butterfly, Vanessa an- 
tiopa Linn. Mark Anniversary Volume, 453-469, i pi. 

(70) Parrott, p. J, 

1927. Progress report on light traps for insect control. N. Y. Agr. Exp. 

Sta. paper presented at Ann. Convention of Empire State Gas 
and Electric Assoc. Oct. 7, 1927. 

(71) Parsons, J. H. 

1924. An introduction to the study of colour vision. 2d ed., Cambridge 

Univ. Press, illus. 

(72) Peterson, A. 

1925. A bait which attracts the oriental peach moth (Laspeyresia 

molesta Busck). Journ. Econ. Ent. 18:181-190, 2 figs. 

(.72,) 

1927. Some baits more attractive to the oriental peach moth than black- 

strap molasses. Journ. Econ. Ent. 20:174-185. 

(74) AND HaeUSSLER, G. J. 

1928. Response of the oriental peach moth and codling moth to colored 

lights. Ann. Ent. Soc. Amer. 21:353-379, 4 pis. 

(75) Pruffer, J. 

1923. Observations et experiences sur les phenomenes de la vie se.xuelle 

de Lymantria dispar L. Bull. Acad. Polonaise Sci. et Lettres, 
Serie B. Extrait, 1-9. 

(76) 

1924. La phenomene d'allechement des males par les femelles chez la 

Lymantria dispar L. Trav. Soc. Sci. et Lettres de Vilno 1(5): 
1-12, 2 figs., I pi. (In Polish.) 

{77) 

1927. On sense organs and the innervation of the antennae and the wings 
of Saturnia payri L. and their relation to the phenomenon of 
the luring of males by females. Trav. Soc. Sci. et Lettres de 
Vilno 3 (8) : 1-84, 7 pis. (In Polish with title and summary in 
English.) 

(78) Rath, O, vom 

1888. Ueber die Hautsinnesorgane der Insekten. Zeitschr. Wiss. Zool. 
46:413-454, 2 pis. 

(79) SCHENK, O. 

1903. Die antennalen Hautsinnesorgane einiger Lepidopteren und 
Hymenopteren mit besonderer Beriickrichtigung der sexuellen 
Unterschiede. Zool. Jahrb. Anat. 17:373-618, 4 figs., 2 pis. 



NO. lO TROPISMS OF LEPIDOPTERA McINDOO 59 

(80) Schroder, Chr. 

1912. Handbuch der Entomologie. Jena. 

(81) Snodgrass, R. E. 

1926. The morphology of insect sense organs and the sensory nervous 

system. Smithsonian Misc. Coll. 77 (8) : 1-80, 32 figs. 

(82) Spuler, a. 

1927. Codling moth traps. Wash. Coll. Sta. Bull. 214, 12 pp., 4 figs. 

(83) Stear, J. R. 

1928. Some results with bait pans against the oriental moth, L. molcsta, 

Busck. Journ. Econ. Ent. 21:565-571. 

(84) Stricht, O. van der 

1909. Le neuro-epithelium olfactif et sa membrane limitante interne. 
Mem. Acad. Roy. de Med. de Belgique 20 (2) : 1-45, 2 pis. 

(85) Tragardh, I. 

1913. Oil the chemotropism of insects and its significance for economic 

entomology. Bull. Ent. Research 4:113-117. 

(86) Turner, C. H. 

1914. An experimental study of the auditory powers of the giant silk- 

worm moths (Saturniidae). Biol. Bull. Mar. Biol. Lab. Woods 
Hole 27:325-332. 

(87) and Schwarz, E. 

1914. Auditory powers of the Catocala moths; an experimental field 
study. Biol. Bull. Mar. Biol. Lab. Woods Hole 27:275-293. 

(88) VOGEL, R. 

191 1. Ueber die Innervierung der Schmetterlingsfliigel und iiber den 

Bau die Verbreitung der Sinnesorgane auf denselben. Zeit- 
schr. Wiss. Zool. 98:68-134, 14 figs., 3 pis. 

(89) 

1912. Ueber die Chordotonalorgane in der Wurzel der Schmetterlings- 

fliigel. H Zeitschr. Wiss. Zool. 100:210-244, 8 figs., 2 pis. 

(90) Washburn, M. F. 

[1923]. The animal mind. New York. 386 pp., illus. 

(91) Yerkes, R. M., and Watson, J. B. 

191 1. Methods of studying vision in animals. The Behavior Mono- 
graphs X (2) : IV -f 90, 13 figs. 

(92) Yetter, W. p., Jr. 

1925. Codling moth work in Mesa County. i6th Ann. Rep. Coll. Sta. 
for 1924, Circ. 47:32-40. 

(93) Yothers, M. a. 

1927. Summary of three years' tests of trap baits for capturing the 
codling moth. Journ. Econ. Ent. 20:567-575, i fig. 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOLUME 81, NUMBER 11 



Kobol^i»s jFunb 



ATMOSPHERIC OZONE: ITS RELATION TO 

SOME SOLAR AND TERRESTRIAL 

PHENOMENA 



BY 
FREDERICK E. FOWLE 




(Publication 3014) 



CITY OF WASHINGTON 

PUBLISHED BY THE SMITHSONIAN INSTITUTION 

MARCH 18, 1929 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOLUME 81, NUMBER 11 



IHobokins jFunb 



ATMOSPHERIC OZONE: ITS RELATION TO 

SOME SOLAR AND TERRESTRIAL 

PHENOMENA 



BY 
FREDERICK E. FOWLE 






(Publication 3014] 



CITY OF WASHINGTON 

PUBLISHED BY THE SMITHSONIAN INSTITUTION 

MARCH 18, 1929 



Z-^c Bovb (§aitimoxt (pteee 

BALTIMORE, HD., V. 8. k. 






ATMOSPHERIC OZONE: ITS RELATION TO SOME 
SOLAR AND TERRESTRIAL PHENOMENA 

By FREDERICK E. FOWLE' 

The reduction of the measurements of the output of radiation from 
the sun obtained at the Smithsonian station on Table Mountain, 
California (altitude 2.300 m.), encountered some difficulty which did 
not seem to be present at the station at Montezuma, Chile (altitude 
2.900 m.), in the southern hemisphere. Preliminary reductions showed 
the presence of a direct relationship between the values obtained at 
Table Mountain for the radiation from the sim and the amount of 
ozone above that station. A yearly march present in the Table Moun- 
tain solar results, together with other irregularities, were eliminated 
when proper allowance was made for the amount of ozone al)ovc that 
station. 

That ozone plays an important part in the interception of radiation 
coming to us from the sun, especially at the violet end of the spectrum, 
has been known for some time. It exerts absorption in the following 
places in the spectrum : ' 

(1) A very strong band in the ultra-violet, 0.2300 to 0.3 lOO//. 
with its maximum at 0.2550/x (the Hartley band). 

(2) A complicated group, extending roughly from 0.3100 to 
0.3500JU. (the Huggins band). 

(3) A group in the yellow and red. 0.4500 to 0.6500/x (the 
Chappuis band). 

(4) A band in the infra-red between 9 and i i//. 



* A preliminary report of this research was read at the 9th annual meeting 
of the American Geophysical Union, April, 1928 (Ozone in the Northern and 
Southern Hemispheres, Journ. Terr. Magn. and Atm. Electr. 33, 151, 1928). 

* Adapted, with alterations in the wave-lengths of the infra-red band, from 
" The absorption of radiation in the ui)i)er atmosphere," C. Fabry, Proc. Phys. 
.Soc. 39, I, 1926. 

Smithsonian Miscellaneous Collections, Vol. 81. No. 11 



2 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

The longer wave-length portion of the Hartley band ( i) has been 
used by Fabry and Buisson ' and others to measure the amount of 
ozone in the atmosphere. On June /, 1920, they found an equivalent 
layer of a little more than 3 mm. at normal temperature and pressure 
(ntp). They estimated that at 0.2800/X the ozone absorption would 
reduce the incident solar energy to lO"^'' of its entering value. Ozone, 
therefore, by its absorption in this band, limits the solar spectrum 
at its violet end as observable at the surface of the earth. Dr. 
Dobson ^ uses this band for measures both of the amount and the 















MountWilson 




^ 








1910-1911 




^y"^^ 






z 



CL 
X 


CD 
< 




x^ 










I 
a. 
./I 


2 

5 


0^ — 
^^ 












i^ 1 z 


3 


4 


15-4 
5*10 X 


0.5623^ 4729/^. 


4273/x 


.3976/. 


.3760/x 



Fig. I. — Atmosplieric absorption coefficients showing ozone band (Fowle). 



height of atmospheric ozone. He found a height of 30 to 40 km. 
above sea-level. 

The Huggins band (2) was used by Cal^annes and Dufay ' for 
measures of the altitude of the ozone layer by light reflected from 
the zenith at the time of the setting sun. They foimd an altitude of 
40 to 50 km. above the earth's surface. 

The Chappuis band (3) is used in the present research. The band 
in the infra-red (4) is of importance because of its location at a 
wave-length where otherwise the atmosphere would be nearly trans- 



^Journ. de Phys. 2, 197, 1921. 

' Proc. Roy. Soc. iioA, 660, 1926; 120A, 251. 1928. 

"Jonrn. de Phys. ct le Rad. 8, 125. 1927. 



NO. II 



ATM OS I' H K R 1 C (Y/A) N E FO WLE 



parent to radiatiuii out-going from the earth. It was ol).serve(l in the 
laboratory by Ladenburg and Lehman,' and bv the writer in the 
solar spectrum." 

A set of atmospheric transmission coefficients, freed as carefully 
as was possible from the effects of non-selective absorptions due to 
water vapor, dry dust, and particles associated with water vapor and 
called wet dust, was published by the writer in earlier i:)apers.' The 
observations are .shown in figure i, redrawn from Fabry's article 
{loc. cit.). Cabannes and Dufay* used this data to .show that the 




I'lc. 2. — Almosplicric ab.sorption in Chappuis yellow ozone band (Colanse). 



departures from the straight line of the points at wave-lengths greater 
than 0.4729/i were caused Iw ozone present in the atmosphere. Mak- 
ing the assumption that the atmospheric ozone amounts to 0.32 cm. 
ntp., they used the differences of ordinates between the observed 
jjoints and the straight line, in the region of ligiu'e i, just indicated, 
to calculate values of the absorption coefificients of ozone for a 
standard dei)th of 1 cm. ntp. Figure 2 shows the 7 resulting values 
plotted as circles and also a curve showing transmission coefificients 



' Ann. d. Phys. 21, 305, 1906. 

'' Smithsonian Misc. Coll. 68, i, 1917. 

^ Astrophys. Journ. 38, 392, 1913 ; 40, 43.=^. iQM- 

* Journ. de Phys. et le Rad. Sept. 1926. 



4 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

for I cm. ozone as obtained in the lalioratory by Colange.' The 
agreement is remarkable. The layer of ozone used by Colange was 
1 8 cm. ntp., and from this the above curve was computed for 
I cm. ntp., by Bouguer's formula. 

The same authors," using a somewhat similar process, later utilized 
published observations, made by Smithsonian observers at their various 
stations, for further determinations of the ozone above these stations. 
These data had not been corrected for water vapor; also the values 
were taken from somewhat smoothed curves drawn through the 
plotted observed points. Further, because of gradually progressive 
changes in the transparency of the sky, comparatively few days furnish 
observations which are good enough for the above treatment. On 
these several accounts the investigation just cited is not fully satis- 
factory. In the following discussion only the original observations 
are used and they are treated by a method probably nearly independent 
of sky changes. 

The results presently to be considered are to a considerable extent 
a by-product of spectro-bolometric observations originally made for 
the determination of the radiation emitted from the sun. X'alues 
from about i,ooo days have been utilized. In the ordinary reductions 
of this work, the ordinates of the solar energy curves (generally 
6 curves per day) obtained with a 6o° u. v. glass prism had already 
been read for about half of the days used. It has been the custom 
to read them on our plates at abscissae, among others, of i8, 20, 22, 
24, 26, 28, and 30 cm. towards the violet from the infra-red band, wi, 
at 2/t. These places correspond to wave-lengths of 0.764, 0.686, 0.624, 
0.574, 0.535, 0.503, and 0.475/i., respectively- This spectrum region 
includes the yellow Chappuis band due to ozone. 

A preliminary futile attempt was made to use these ordinates to 
determine directly the depth of the ozone band. The liand is masked 
by the numerous solar lines in that part of the spectrum. Indeed 
Fabry says : " The Chappuis bands have never been observed directly 
in the solar spectrum. I have often looked for them in the spectrum 
of the setting sun, but have never found them." 

However, if the several observations of any day, made at each 
place in the spectrum at different zenith distances, are used to deter- 
mine atmospheric transmission coefficients, and the resulting values are 
plotted against the corresponding deviations, the band is strongly 



' Journ. de Phys. et le Rad. 8, 257, 1927. 

' Journ. de Phys. et le Rad. 7, 257, 1926; 8, 353, 1927. 



NO. II ATMOSPHERIC OZONE — FOWLE 5 

brought out as may be noted in figure 3. This figure shows results 
for days of great, medium, and neghgible absorption in this band. 
The abscissae are prismatic deviations, the ordinates, atmospheric 
transmission coefficients for zenith sun. As the quantity of atmos- 
pheric ozone may be correlated to the amount of energy cut out by 
this band from the radiation coming to us from the sun, the area of 



30 28 26 24 22 20 30 28 


26 24 22 20 


Q^ Deviations Prismatic 




? 

« 




94 s 


/ 


5r / / 


• 




• 
/ 


z / ; / / 


1 

1 

/ 

/• 


' ! / ^ 


/ 


Mean Yearly /„^ , / / 


/ 


88 5unSpotNo*^/80\' / /44 


/ ^^ 


' / '/ 


/ 


' ''/ 


1 


' f f 


/ 


.86 / ,,-• // 


f 


f 




•84 




/' 




' ' ,• 




• / / 




•S^ /MARl5(TaUleMt) /Feb28 (MonTezuma) /May 15 


I^HarquaHala) 


/ 1928 / 1925 / 1921 




.80/ •' 30 28 26 24 22 




• 





Fig. 3. — The Chappuis yellow ozoiio hand. 

this band, reduced to the proper energy units, has l)een utilized as a 
measure of the amount of ozone in the atmosphere. 

A smooth curve is first drawn over the top of the band as indicated 
in figure 3. At any particular abscissa, let o,, represent the ordinate 
on the smooth curve drawn across the band, or, in other words, the 
transmission of the air for zenith sun with no ozone present; Oo is 
the corresponding transmission coefficient for ozone, and a the ob- 
served transmission. Then 

a = aaa^ or ao — a/Oa. 



SMITHSONIAN MISCEIJ-ANEOUS COLLECTIONS 



VOL 



Calling c the corresponding energy at the selected place in the sun's 
spectrum, it may be assumed that approximately the amount of 
energy absorbed from the sun's rays by ozone is 

{— .e) summed for spectrum places 22, 24, and 26. 

The accuracy of these measurements, depending, at the greatest, on 
differences of the order of (0.890—0.860), cannot exceed i part in 30, 
assuming no accidental errors. Further, the measurements extend 
over times of from one to three hours. It is presumptuous to assume 
always a negligible change in the amount of ozone during such 
considerable times. Any change in the general transparency of the 
sky is probably negligible, since it would alfect both the numerator and 
the denominator of the above expression. It takes only 30 seconds 
for the run through the part of the spectrum used, so that the time 
is short to produce differential errors within this band. 

Because the results presently to be given differ so considerably in 
magnitude and range from the values of Dr. Dobson and those asso- 
ciated with him, it has been thought advisable to devote considerable 
time and study to the indications of the Chappuis band. 

Is the discrepancy due to the presence of other atmospheric lines 
within the Chappuis ozone band? A count of the number of atmos- 
pheric lines, designated as such in St. John's recent revision of 
Rowland's Solar Spectrum Table, ^ leads to the following table : 



Spectrum 
range 



Wave-length 
range 



Number of lines 



HoO 



27-29 


o.490-.520/^ 











25-27 


0.52(^.555 


i(> 


I 





23-25 


o.555--'^oo 


311 


244 


43 


21-23 


0.O00-.O53 


81 


104 


42 



In figure 4 the area of that part of the ozone band under trial 
corresponding to the region of the first three lines of the above table 
is plotted against the corresponding precipitable water vapor in the 
atmosphere ; in figure 5, is similarly plotted that corresponding to the 
lower line. No connection with water vapor can be certainly inferred 
from these two plots. What little dependence there seems to be is in 
the wrong direction ; that is, the greater the water vapor, the smaller, 
on the average, seems to be the area of the band. This apparently 
inverse effect probably results because the season of greatest water 



' Carnegie Institution Pulilicatinns, 306, 1928. 



NO. II 



ATMOSPIIKKIC 0Z0X1-: FUVVLE 




Fig. 4. — Abscissae, ppt. 1-hO ; ordinates O,; ; 0.47 to o.6o/^. 




Fic. 5. — Abscissae, ppt. HijO ; ordinates O;; ; 0.60 to o.^O^t. 



8 SMITHSOXIAX MlSCELLANliOUS COLLECTIONS NOL. 8l 

vapor conies considerably later in the year than that for the area- 
maximum of the band, yet before the time for its maximum. 

A far more detailed study of the transmission coefficients in the 
region of this band has been made than was possible with the some- 
what separated measurements in the spectrum made for the solar- 
radiation work. Plates for two days were reread and coefficients 
determined for each maximum and each minimum of the solar lines 
visible in the observed energy curves (tig. 6, curve a). Unfor- 
tunately, between deviations 20 and 22, and 27 and 28, such a process 
was impossible because of instrumental contingencies. The resulting 
coefificients determined independently for the two days of observations 
are plotted in curves b and c. This is a useful transformation, result- 
ing, as it does, in a spectrum, b or c, showing only atmos])heric 
lines, from an energy curve like a where the solar lines are domi- 
nant practically to the exclusion of any indication of atmospheric 
absorptions. 

Assuming for the time being the validity of Bouguer's formula, a 
further step was taken. Entering figure 2 for the corresponding wave- 
length wath the transmission coef^cient determined at place 24 from 
the curve c of figure 6, the amount of ozone was determined. 
With this amount of ozone, and the transmission coefficients at all 
the maxima and minima of the curve in figure 2, an ozone band 
was computed, using the line across the top of the band in curve c 
of figure 6 as the basis. The result is plotted in curve d of figure 6. 
The agreement between c and d is better than could be expected and 
is indeed remarkable. Apparently because the writer is using a purer 
spectrum than Colange, the deflections in curves b and r are more 
marked than in curve d, but the agreement in position is satisfactory. 
Between deviations 26 and 30, the coefficients are too small to expect 
any accuracy. It seems therefore highly probable that practically all 
of this band as observed is due to ozone. 

The writer, as already stated, prefers to express the results which 
follow in terms of a quantity <fairly directly coming from the observa- 
tions, namely, the amount of energy cut out from the incoming 
solar energy by this yellow Chappuis band. These results may be 
approximately reduced to amounts of ozone (ntp.) by using Bouguer's 
formula Avith the constant determined by Colange (loc. cif.) as 
indicated by the following table : 



Band area 30 40 1 50 1 60 70 80 [ 90 100 1 cal. X lO" 

Ozone . 90 I . 160 ! . 200 . 230 . 260 I . 290 ! . 320 ! . 350 I cm. ntp. 



NO. II 



ATMOSPHERIC OZONE — FOWLE 




30 28 



.76V 



26 24 2,2 

PRISMATIC DEVIATIONS^ 



20 18 



Fig. 6. 



lO 



SMITHSONIAN' MISCELLANEOUS COLLEGTIONS 



VOL. 8 1 



The use of Bouguer's formula is unsafe for banded absorptions, 
except possibly for a very pure spectrum, and as an interpolation 
formula. Langley ' long ago showed its inapplicability in a region 
where quite different coefificients of absorption occur, and his logic is 
even more applicable in the present case where these occur in close 
juxtaposition, and in banded spectra where the resolving power is 
comparatively poor. Safer substitutes for Bouguer's formula may 
be employed. For instance, in estimating atmospheric precipitable 
water the writer always uses an absorption curve calibrated as far 
as possible in the laboratory. A curve approximately of the shai)c 



V 



c 



M 
o 



^ AUsorbenl: "thickness 



iMCi. 7- 

indicatetl in figure 7 would be expected. \\'here lines of strong 
absorption occur alternately with those of high transmission, the 
curve of figure 7 does not tend to approach a zero value of / with 
increasing absorbent, but to l)ecome horizontal for a finite value of /. 
Assuming Bouguer's fornnila to hold we should have a straight line, 
tangent to some portion of this curve. In view of the state of affairs 
indicated in figure 7, we should hesitate to use Bouguer's formula 
for computing the amounts of ozone, unless for data requiring very 
little extrapolation from the amounts of ozone used in the laboratory 
to determine the constant of the formula. It may be that these con- 
siderations explain certain discrepancies l)etween Dr. DobstMi's results 



' Ann. Astroplij's. Observ. Smithsonian Tnst. 2, lO, 1908. 



j^O. II ATMOSPHERIC OZONE FOWLE II 

and mine at the same stations. He is working at a spectrum place 
where the coefficient a in the formula, 

/ = /„io-"^' 

is very large, ranging from about i to 4. He is therefore probably 
working far down on the nearly horizontal portion of a curve such 
as is indicated in figure 7 where a large change in ozone makes a 
comparatively small change in the observed spectrum intensity values. 
On the other hand, in the Chappuis band used by the writer, the 
coefficient a is so small, about 0.04, that the band is very difficult to 
observe visually. Therefore we may assume that the writer is measur- 
ing in a band where a small change in ozone produces a great change 
in the observed quantity. In other words, for the amount of ozone 
present in the atmosphere, the Chappuis band is a more sensitive 
indicator of changes in atmospheric ozone than that employed by 
Dr. Dobson. 

With these preliminary remarks, attention may be drawn to figure 8, 
in which recent observations made at Table Mountain with Dobson's 
apparatus, and reduced by him to cm. ozone ntp. are compared with 
the writer's results as expressed in areas of the Chappuis band. The 
average amount of ozone for this interval of time as computed by the 
preceding table from the writer's results is about 0.23 cm. ntp., while 
Dobson finds about 0.22 cm. The range of the variation found by 
the writer much exceeds that found by Dobson, but nevertheless a 
marked correlation exists between the two series. 

The writer cannot leave Dr. Dobson's work without one further 
remark about his method. He states,^ " It has been shown that there 
is a close connection between the amount of ozone in the upper 
atmosphere and the pressure conditions in the upper part of the 
troposphere and the lower part of the atmosphere," and states that. 
" it is remarkable that the ozone situated at so great a height " (40 
to 50 km., as indicated by the results of Cabannes and Dufay, 30 to 
40 km. by Dobson himself) should be so closely connected with 
variations of pressure much lower down." 

Dr Dobson^ uses two methods in his evaluation of the amount 
of atmospheric ozone. In the first he takes as the general atmospheric 
transmission coefficient 



' Proc. Roy. Soc. 120A, 251, 1928. 

" Mp^Not. R. A. S. 86, 259, 1926. Proc. Roy. Soc. iioA, 660. 1926. 



12 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 



■ 1 1 — 

.o 


-1 1 r— 1 1— 

« 


.00 












.O 
xo 





T P 



/ 




O 



H 



o 



fO <v — 



fc 



NO. II 



ATMOSPHERIC OZONE FOWLE 



13 




[ 192 



e 2 

1 1928 

O-0.n f1 Mkr Apr May Ju'n J^l Aafe Sep oit wiv Dec-O-Oan FeU M^ A,ir Wky dJn Jl Aug S^p Oit Niv Dec ^ 
B HarquaHala. Arizona, o Montezuma.Chile. *TaUle Mt.Caiifornia. 

^JtMtiBrukkaros.A-frica 

Fig. 9. 



H 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOL. 8l 



where A' = /? + 8 + ax 

[i is the absorption coefficient (kie to small particles, 
8 is the absorption coefficient dne to large particles, 
a is the absorption coefficient due to i cm. ozone ntp., 
X is the thickness of ozone atmospheric in cm. ntp. 

Now it seems to the writer that the very variations with atmos- 
pheric pressure which Dr. Dol)Son throws into x, belong fully as 





^ 








,L^ 








_ -^-T" 






^J'— " 






6- ''^ 




- 




OZONt--N. HEMISPHERE ' 








S. '' H / 








^ SUN SPOTS ^r- / 




( 


) ^ 


/ ?k 




/ 


8 




/ 


/ 




( / 


V / 






1 / 


>< 






4- // 


Ty 


- 


7 


/ / 








1 / 








1/ 








3- J 




- 


6 


''\ / 








"^ v 








"^v V 








^0^ ^ // 




- 


5 








1— ^^^-«N^ iv- / 








o ^Giv x"/ 








^ ^v^v ^ f/ m 








^1- xn .^y^ /N 




- 


4 




>3 








1 




•2 


1921 1922 1923 1924 1925 1926 


1927 


1928 



Fig. 10. 



legitimately, and very probably, to both ^ and 8. All this relates to 
what Dr. Dobson calls his " long method," dependent upon several 
observations during the day. In his second or " short method " he 
uses the expression 

(log Jo-log I'o) - (log /-log r) - (13- ft') sec ^ 
(a — a) sec ^ 

In the determinations by this " short method " he assumes that 8 
does not vary with A and uses a value for ft obtained from the formula 



X- 



NO. II 



ATMOSPHERIC OZONE FOVVI.E 



15 



of Rayleigli. Although both these assumptions may he allowable up 
to a certain accuracy it seems likely that from either of them a 
variation dependent upon the atmospheric pressure or water vapor 
may have been introduced. 

Let us now turn to the results of observations made at Hanjua 
Hala (altitude 1,770 m.) and Table Mountain (2,300 m.) in the 
United States of America, Montezuma (2,900 m.) in Chile, and 
Mt. Brukkaros (1,600 m.) in Africa, embodied in the following 
table and figures 9, 10, and 11. The table gives only the monthly and 




Fig. II. 



yearly mean^; hence the plotted points, especially in the plots of yearly 
means, figures 10 and 11, depend upon a considerable number of day's 
observations but not always every successive day. The Wolfer spot 
numbers and the magnetic character values here given are computed 
employing only the days of radiation observations. In my preliminary 
paper, already referred to, the plots related to daily values, and even 
with the few values there utilized from the 1926 and 1927 observa- 
tions at Table Mountain, showed a distinct correlation between the 
ozone, the spot numbers, the magnetic character and the flocculi for 
the corresponding days. 



i6 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 



THE OBSERVATIONS 



Month 




Ilarqua Hala, 



Ozone 
area 



Wolfer 
spots 



Magn. 
ch. 



34 


II 


0.7 


47 


2.1 


T.O 


50 


8l 


■ y 


56 


15 


I.O 


55 


8 


•7 


45 


4 


•7 


52 


i8 


•4 


49 


II 


.2 


46 


6 


.8 


34 ! 


4 


.8 


27 


4 


.1 


31 


10 ; 


.2 




Month 



Jan. 

Feb. 

Mar. 

Apr. 

May 

June 

July 

Aug. 

Sept. 



Harqua Hala, 1923 

Ozone I Wolfer I Magn, 



No. 
obs. 



21 

23 
27 
48 
52 
33 
21 

31 
37 



7 

2 

10 



3 
10 



uct. 
Nov. 
Dec. 


3 
I 


27 
43 
38 


12 

7 



Year 


37 


34 


6 



3 
2 

73 



Ozone Wolfer 
area | spots 




Montezuma, 1923 



2 


24 


10 


4 


34 


2 


10 


26 


3 


i 12 


28 


7 1 


7 


37 


3 


14 


36 


13 1 


6 


32 


2 \ 


4 


35 


2 ! 


5 


41 


10 ' 


4 


36 


8 



35 
19 

32 



Magn. 
ch. 



0.9 

.6 
•4 
■4 
•5 
•4 
•4 
•4 
•4 
•5 



0.6 



NO. II 



ATMOSPHERIC OZONE — FOWLE 



17 





Harqua Hala, 


19^ 






3 


Montezuma, 


1924 




Kn. 
h. 


Alonth 


1 No. 
obs. 


Ozone 
area 


Wolfer 
spots 


Magn. 
ch. 


Month 


No. 
obs. 


Ozone 
area 


Wolfer 
spots 


Ma 

c 


Jan. 


4 


48 


2 


0.9 


Jan. 


4 


35 





0.5 


Feb. 


3 


49 


7 




2 


Feb. 












Mar. 


2 


28 







5 


Mar. 


4 


30 







8 


Apr. 


1 


61 







2 


1 Apr. 


4 


32 


10 




3 


May 


3 


26 


14 




8 


i May 


4 • 


32 


22 




7 


June 


/ 


39 


18 




7 


June 


4 


34 


22 




4 


J Illy 


4 


39 


9 




8 


July 


4 


40 


25 




6 


Aug. 


I 


22. 


II 




I 


1 Aug. 


5 


40 


II 




I 


Sept. 


3 


47 


19 




6 


Sept. 


4 


33 


22 




5 


Oct. 


5 


48 


25 




6 


Oct. 


4 


40 


26 




6 


Nov. 


3 


iz 


31 




7 


Nov. 


5 


26 


22 




6 


Dec. 












Dec. 

1 


14 


25 


21 




4 


Year 


36 


41 


15 


0.6 


Year 


56 


33 


17 


o.S 





Montezuma, 1925 






Table 


Mountain, 1926 






No. 


Ozone 


Wolfer M 


agn. 




No. 


Ozone 


Wolfer 1 Mc 


»!fn. 




obs. 


area 


spots 


:h. 




obs. 


area 


spots 1 c 


h. 


Jan. 


ID 


29 


6 


5 


Jan. 


16 


88 69 


9 


Feb. 


3 28 


15 


5 


Feb. 


II 


84 68 


6 


Mar. 


17 i 42 


22 


4 


Alar. 


15 


84 50 


8 


Apr. 


13 


44 


29 


5 


Apr. 


14 


90 


38 


8 


May 


13 


44 


38 


4 


May 


24 


90 


68 , 


6 


June 


14 


49 


24 


8 


June 


18 


81 


74 


5 


July 


7 


43 


37 


3 


July 


23 


'J2 


57 


5 


Aug. 


2 


42 


19 


8 


Aug. 


22 


88 


62 


5 


Sept. 


4 48 


63 


9 


Sept. 


28 


(>7 


62 


7 


Oct. 


3 


38 


43 


7 


Oct. 


24 


62 


66 


6 


Nov. 


2 


51 


54 


8 


Nov. 


9 


63 


50 


5 


Dec. 


2 


38 


76 


4 


Dec. 


7 


71 


80 


4 


Year 


90 


42 


29 


•5 


Year 


211 


78 


62 


7 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOL. 8i 



Montezuma, 1926 



Month 



No. I Ozone VVolfer j Magn 
ODS. I area ' ' 



Table Mountain, 1927 



Jan. 


I 


34 


Feb. 


I 


^9 


Mar. 


2 


30 


Apr. 


4 


28 


May 


'2. 


27 


.hine 






J lily 


3 


?>7 


Aug. 


2 


42 


Sept. 






Oct. 


3 


?>7 


Nov. 


2 


40 


Dec. 







84 

162 

38 

43 
38 

34 
61 



7i 



Jan. 

Feb. 

Mar. 

Apr. 

May 

June 

July 

Aug. 

Sept. 

Oct. 

Nov. 

Dec. 



4 
4 
5 
5 
4 
3 
12 
6 

5 
6 



Ozone I Mas-n. I Wolfer 
area ch. | spots 



72 

78 

76 

80 

79 

63 

67 

66 

66 

59 



80 

87 

87 

79 

65 

40 

SI 

60 

60 

66 




0.4 
.8 

■5 
.8 

•4 
•3 
. I 
.8 
.8 
•7 
•4 
i.o 

0.6 



Table .Mountain, 1928 



Month 



Jan. 

Feb. 

Mar. 

Apr. 

May 

June 

July 

Aug. 

Sept. 

Oct. 

Nov. 

Dec. 



Year 




3 


45 


61 


2 


24 


65 


28 


38 


75 



NO. II ATMOSPHERIC OZONIi FOWLE I9 

From the data of the i)receding- tahic and the corresponding figures 
several phenomena are notable : 

(i) There is a very decided yearly march, as lias hcen noted l)y 
other observers. 

(a) In the northern hemisphere we may take the maximum and 
minimum of this march as follows : 

Maximvim Miiiiimun 

1 92 1 March' Sept. 

1922 March Nov. 

1923 April-May Aug. ? 

1924 April Aug. ? 

1925 (April, Dobson) (Oct., Dul)son) 

1926 April-May Oct. 

1927 April-May (Ai)ri], lUiisson) Nov. (Nov.. r)nisson)'' 

1928 May Sept. 

( 1) ) and in the southern hemisphere as follows : 

Maximum Minimum 

1923 Sept. March 

1924 Aug.-Sept. March 

1925 ? Feb. 

1926 Aug. April ? 

1927 not definite not definite. 

whence : 

(2) In the 3'early march the maxima and minima occur at nearly 
the same seasons of the year in the northern and southern hemi- 
spheres, though of course not in months of the same name. The 
maxima occur between April and May, the minima between August 
and November in the northern hemisphere and vice versa approxi- 
mately in the southern. 

(3) A marked correlation exists between the ozone and the W'olfer 
sun-spot numbers for the observations of the northern-hemisphere 
stations, as indicated in figures lo and ii The range of the yearly 
means for the area of the yellow band is from 20 to 100 (see fig. 9). 



' The writer is inclined to discount the appearance of the low value in May. 
1921, as abnormal, possibly due to erroneous observing, and to consider the 
general march of the curve as indicating the minimum in September. Somewhat 
similar judgments occur later in the table. 

■ C. R. 186, 1229, 1918. 



20 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 8l 

(4) 111 the southern hemisphere no such strong correlation is appar- 
ent between the spot numbers and the ozone. The corresponding 
range is only from 20 to 30. However the errors of the readings 
of the area when this is small are comparatively great ; indeed the 
observations do hint a slight relationship. 

The writer suggests that the following considerations point to a 
fifth deduction from the observations. 

The ozone present in the upper air has been generally considered 
as formed from the oxygen there present by the action of ultra-violet 
light from the sun. Radiation of very short wave-length (less than 
0.1850/X,) acts upon oxygen, transforming it into ozone. It is not 
improbable that radiation of this wave-length reaches the earth from 
the sun. If so, it must produce ozone in the earth's atmosphere, but 
only in the highest levels, because it cannot reach the lower strata. 
Radiation of wave-length 0.1850/i. is completely absorbed by 10 m. of 
air at ntp., and could scarcely penetrate lower than a stratum 40 km. 
above the earth. On the other hand, radiation lying between 0.2000 
and 0.3000/X decomposes ozone, and between these two opposite 
actions a state of equilibrium would be established. Since the ozone- 
destroying wave lengths penetrate deeper into the atmosphere, this 
naturally limits the ozone layer to a high altitude. 

It is possible though that another agency than ultra-violet light 
works to produce ozone. The investigations of Milne ^ and Pike ' 
indicate the great probability that electrified particles gain such 
velocities on the sun that they are projected outwards into space from 
that body. Mme. Curie ' has shown that the a-particles emitted from 
radium salts ozonize oxygen. Electrons with a velocity of 1.80 X 10* 
cm./sec.^ are capable of producing ozone from oxygen. It is also 
produced by the silent electrical discharge. 

Suppo