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SMITHSONIAN
]. J-
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
;?cv\i
ixl
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
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7.-.i
y
-N
Caniliriau l'"us>il> frdin iht- .Muhavf Desert.
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
^^^B
w^^^
I^^H
,^_:3^,,.
^Bl
f J
' J
1^/
, :ii:
' V 'C " ■
Lainlinaii Fossils from the Mohave Desert.
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:
w.
'o^P^
ik7l Zl
(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
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o
\
\
8
00
o
\
V A
o
UJ
—1
iL.
UJ
o
\
>
-J
<
CD
e
6
4
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-4-
v
2 +
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6 -^
6
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-12
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-le
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-2C
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DE
.GREE5
C.-2.
}
~^
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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.
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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.
Xo
2.-.3i'^i.
No.
-'.-.U'-^').
No.
-'.x?-'-'().
X(i.
-\=;.i-'-''J.
X,,
-'.^.V-'O.
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
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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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