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Poe hie * ana are pra ep Bere i“ ap inenay hpes' or7t Price neta irencn lec ate esse gt toe esac arene wepran oe Spates weet POM Liairaled shade pee pevaaye: BIW Fi beeen ie ay eaary) ene Arun Ie A od o SrA eta Blau eet team aati Sarto dee herd Pipes reise pense es! fits 7 eno ®, PN YGED a pee ie ea Cate ei Bs epee ‘ Reuxict aw Craue) egy Pe S34 Var ~ % SCY KD OMS OT Uy = mS fo) eras oe eS “ fo) Nove rrr a \ 3 Sa = cae =" ae <| zm ay Poy z TUTION NOILNLILSNINVINOSHLINS ,S31YVNGIT” LIBRARIES SMITHSONIAN” INSTITUTION NOl o ay One ro) - 5 gb = 5 = o = o = oO = 6 = a =) cad = a =a 7 = a a = a eX ep) m 22) ae no” = oO q = o < @) z o = vudgl ee SMITHSONIAN RATION NOILNLILSNI NVINOSHLINS Saluveai LIE z ” z o = o z yy, < = < = < = = mm =I x As ar 9.5 Nw 3 2 Ne 2 = “ Ye. \ASSQy, 2 On: . 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SS oe _ {o) = oO = a Zz -! z = a = V¥di7 LIBRARIES SMITHSONIAN INSTITUTION NOILNLILSNI NVINOSHLINS S31¥VuaIT LIE fz ~ z w z 5 o 2 “0 pd wo ° elles io] >. es) Le 7 [= a [=z > Fee > = > 2 > (2 2 rahi = — = 2X = 5 = r = = = 4 cA oatih Nor Z 7 wie D TUTION,,, NOILALILSNI_ NVINOSHLINS, Sa1uvua ou BRARIES SMITHSONIAN _ INSTITUTION, NO! i. ao Pe 4\ Y) ty) oy NE a a Ne = LMR - WN ey re, ~, Ne “dd pn ‘yy J Lf, ww ty” it SJ Ql 5 “uy 9 “oes” 5 OURO Ni og Nae G8 4 I = x = a NOSHLIWS _S31YVYdIT LIBRARIES SMITHSONIAN” INSTITUTION | NOILOLILSNINVINOSHLINS _ f S = Np ne: S = S be E be = me) za 2) = > 4 is > = > = = 2 E, 2 F = F zZ m 2 m zZ a z INSTITUTION NOILMLILSNI_ NVINOSHLINS, Sa PAV Mie eS RARTES | SMITHSONIAN <4 = ; z = ) aa = < z= Os a z Si z = = ro) N\ = c O x 9 N; x re} 2 2 NW 8 2 g Z XN § 2 E vez z 2 eE NY 2 E ee z = Se 5 INOSHLINS S31YVYGI7 LIBRARIES SMITHSONIAN (NS TInUgteN ese! Skool NYINOS NS 2 uw A Mt 2 WwW = WwW <= nn w = = « = x ae in =o oc < = < 2] < = kt cc c cc Cc oc =| oc = 3 cm. = rl S oO a = am} S 3 =z = ITHSONIAN INSTITUTION NOILNLILSNI NVINOSHLINS S31YVYdIT LIBRARIES SMITHSONIAN = z G z ie = = ac) 2 o ° ow 2 “0 ) = 2 & 2 =. Fs) 2 = =. E 2 = 2 = - a = = = = , m ” m ” m a” mi INOSHLIWS Sa 1uyvua Tul BRARIES, SMITHSONIAN NGIEATITSN| NVINCS BUNS = = Ke = = g = = = P= NS OS > = z = ze 5 OO WSs ™ pa (e) ae (eo) Se a an - Cea mp) an n a [oye ia) \. [e) ac [o) 25 (2) z = LY: Zz E z = = > ° = > Ss > ¢ = > 2 wo tS eed a a 7) = ITHSONIAN INSTITUTION NOILMLILSNI_NVINOSHLINS Salavagiq_ LIBRARIES SMITHSONIAN _ 15 7 a ea 5 Bsa ye eaneaar = 4a NS fz = x. i fy = = = : = = = Ne = = Se] Lin 5 —_ AYA —— @ = Be : B =a WY Gg = a) z a) z 7) : z INSTITUTION NOLLMLILSNI _NVINOSHLINS,S3 | uVYGIT_ LIBRARIES SMITHSONIAN an z < = “ae = E = \ = = =] me =| 2 oO Se : O ae {e) Se (e w” = —. Ww m wn . Ww” y n Y = x ~ SO BS fo) E 8 ro) I E Avy 2 = é = » = : Se 5 . Ph Ale: 3 INOSHLINS S3IYVYGIT_ LIBRARIES SMITHSONIAN INSTITUTION NOILALILSNI_ NVINOSHLIWS | ul = ws = tl 5 u aX = o | a = a s 4 =) < | < =A ie Re Na a c food Cc o c a SS \ oO = a. = fee] a a SS - oO ae fo) ex je) = 4 = say z = 2 - ‘ITHSONIAN INSTITUTION NOJLMLILSNI NVINOSHLINS S3I1y¥vYgIT LIBRARIES SMITHSONIAN cs z is z - z Z “0 a o ° o = “9 es) E 2 B D = 2 > Fa 4 = > = % > ee) — — [= pe) —? 2 = - ae rs = = = Saye 2 2 a2 ; ao oe INOSHLINS, S31YVYAIT_LIBRARIES, SMITHSONIAN INSTITUTION NOILALILSNI NVINOSHLIWS | se: = ee 7) Sem) = es Xs = SY =< §\ = SS SEL 3 ‘Ss ON =| ad fi i . = oS a ‘ \S =r x > (% wNe = RO 5 ust Zy' % A . 2+ Kamm 2 SG f= ui f= FAM | coy UNIVERSITY OF CALIFORNIA PUBLICATIONS IN ZOOLOGY Vol. 13, No. 11, pp. 243-446, pl. 13-37, 7 text figs. April 17, 1916 A STUDY OF THE STRUCTURE OF FEATHERS, WITH REFERENCE TO THEIR TAXONOMIC SIGNIFICANCE WBY Oey (tee Oe ASA C. 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A Study of a Collection of Geese of the Branta canadensis group from the San Joaquin Valley, California, by Harry 8. Swarth. Pp. 1-24, plates 1-2, 8 text figs. November, 1913.20.20 80 2. Nocturnal Wanderings of the California Pocket. Gopher, by Harold C. Bryant. Pp. 25-29, 1 text fig. November, 1913... 05 3. The Reptiles of the San Jacinto Area of Southern California, by Sarah Rogers Atsatt. Pp. 31-50. November, 1913.02.20. -20 4. An Account of the Mammals and Birds of the Lower Colorado Val- ley, with Especial Reference to the Distributional Problems Pre- sented, by Joseph Grinnell. Pp. 51-294, plates 3-13, 9 text figs. DE BrChn ys BOTS yes aT a Sa ee 2.40 5. Aplodontia chryseola, a New Mountain Beaver from the Trinity Region of Northern California, by Louise Kellogg. Pp. 295-296. 6. A Previously Undescribed Aplodontia from the Middle North Coast of California, by Walter P, Taylor. Pp. 297-300. Nos. 5 and 6 in one cover, April, 1914 .....2.2.. cece cccceee ce eleceeeeeeee 05 7. A Second Species of the Mammalian Genus Microdipodops from California, by Joseph Grinnell. Pp. 301-804, April, 1914............ .05 8. Distribution of River Otters in Oalifornia, with Description of a New Subspecies, by Joseph Grinnell. Pp. 305-310, plate 14. Octo- hy ret he Seana cits csaes As” Ol Re EMR ena SON NCAR MMR a aN -05 9, Four New Pocket Gophers from California, by Joseph Grinnell. Pp. 311-316;2' November, 19248 i ie ee .05 10. Three New Races of Vespertilionid Bats from California, by Hilda Wood Grinnell. Pp. 317-321. December, 1914.20.22... cece ceeeee .05 11. Eutamias sonomae, a New Chipmunk from the Inner Northern Coast Belt of California, by Joseph Grinnell. Pp. 321-325, 1 text figttre.:: January, LOLB ese as ee or ea .05 12. Batrachoseps major and Bufo cognatus californicus, New Amphibia from Southern California, by Charles Lewis Oamp. Pp. 327-334, YS) | Rae 0: hs oe A eae AB: Geen os CoA CL Ue See Mes Rs Wool CET AIMED eek poe 10 UNIVERSITY OF CALIFORNIA PUBLICATIONS IN ZOOLOGY Vol. 13, No. 11, pp. 243-446, pls. 13-37, 7 text figures April 17, 1916 A STUDY OF THE STRUCTURE OF FEATHERS/ WITH REFERENCE TO THEIR TAXO- NOMIC SIGNIFICANCE Whe ray y v7, ASA C. CHANDLER ' CONTENTS EDSSATERTG CO CLIT ET Tams ea ere er reece ora, hr on een ee ee 5 Ac arene ee Objecisands scope Of pap Cie rete ee econ cess ee cars seth eecoe oes eee ENCVS ION Ara UTES af Sy ee ee eee ee TSS) 0) 0) La ae a a ea ee a eee ele ee =n es ee ne a ee Oe MRP onee oa PINOT GT CLEVE ULL Ce ye eens ee eee ec ee Se aad cee ceeds ess Seance JW SN AL 6 ES Se ne oe eee re Am ete Ge TET Ul IVE OT: NOLO Si yieresee ee este eters aera eee eh a es oe oe ae PESTA CS gemeseec eee tee sale bene cats une ae eee sen AAG ets Dae ae oe ch 55 ed ae eae 2 IDES rea Oey apel Cop go Gb Bean bY Kee) ke Rea ae ae ee Se et eee ORV EET CLO Vy Ny ee torent ae toe ne Aes ng ene LS RENE) Pee a eee (Oni efat Wave UN SEsi HOS) oie ele ee Mente’ eee Narn nee See Re NA E RES Ren one toe oe Ae Eevee Sean ee ae 259 IN CS CUI S wile AUTO TS ype escent eres a sak a eS ee ice re ee ak et 259 PSU CTRL T1t1y © Ser ee ee eet Cree ee cS en Ne EE ee a eet 260 COP REN ORM : aiCSEEY INS) CTS eee he eter ec SO ne es ae ee 263 HERCTIUIS OS seco seeccn coe ee ses se ces ee Coe ee ens aS eee eewe ccs eae apesasecooetlc det caeleachedattee tmas 263 HEV WIGS ese ec ee a a se Sag Sec ce seem ea tat eee es ee cece 268 Unspecialized contour feathers 269 Ornamental plumes ..................... 2 PARRA Ba (COV CRUS) (roe ocasoee seen ne eeeneanaeenes = PANES Haciniwbristles andmeyelashesa-. cts. e ne eee 273 VER EENGVECTIN WS eh df Set a a ee, Se ee ce 274 WOLOT TOUCH ON eee ae secs bee sean cete eee cece ce cov eee lone osecian2 MM oncoclsuec: seslcsbereudenozsceuenees 274 TSOCEliye i De PLOCGUCTIOMM OS COLOLS pes ccene ee osc e scscc cmc c ce eeare oe open cece one-star 274 Effect of albinism on structural color modifications —..............2........ 279 Teertre te, US © OS INAH nH 00 EH) ee oe 280 TAF St eG AEG CO Oe eR A ee a NER ee 280 Intraspecific and phylogenetic modifications —......0. 222 eeeeeeee ee 280 WhASSIN GALTON COD CEC ence erent sarees ate ee eee te en emerson 282 IMETINO GS Ot "COMIPATATLV.C St Uy ercere ooo os on ome tatn See ccaeercanoeeeees dasncacsacbacte eeseaces 283 BRT UTM aoe ls ean ne a aeons ee eS RU At ss eR Sn aE Nate ee ee ESE 284 Ongers Str wthiOnifOrmesy covcee.-ceqcerssscee sc cme nen ns nnn seus Sese cena ce seams atc ney cecaseeeec eves 285 244 University of California Publications in Zoology [Vou. 18 Order Rheiformes ...... Order Casuariiformes Order: Aptery eiformes; 22-25 enter ee a 293 Carimaitare ek A oe ee oe se ene ee eee 296 Order Sphemisciformes: 2c ence eee coer arcane eee eee eens 296 Order Colymbiformes cee ese ae ee 298 Order Procellariiform Gs ieee ee eee 302 Order (Cicomiiformes: Soccer een as sect e oe ease 307 Stborder STeSanOMOdes Seis ceeeeceesses ese ccendepscenccteesceweceessoneeceacecs. deearnanceee 307 Suborder GC icomdaey cece ceexe ese coe ae eee are ee ee 318 Suborder Ardeae: .ecesckio Stes ee eee ee 321 Suborder BEWOCMICOPLREN sees as crenata reece cea eee 325 Order VAMSer TRONS | Sewer ee ee 327 Suborder -Anseres: 2253.) ee ee oes Se eee 327 Suborder’ Palamed caer a2 2c.- tse scccssecerccsevecst cate weecewcucccncceescesese see eee 330 Order Wale omihorw es) eae eras c asc ne eae caee e e Stubord ers Cathet @ re cese ace secesceeeececeeceeecee eaene ecec cee eeeenee Suborder Gypogerani Suborder Accipitres - Order Galliformes ... Suborder Galli -... Suborder Turnices Order Crypturiformes ................ ORdernG ruil form cscs eee Order Charadriiformes ...................-------- Suborder Laro-limicolae -.................- 354 Suborder Pteroclo-columbae ............--..---------.------- . 358 (Oyo Vey CORO UU DIPS CONES) ee ener nee emer ese ee ceenen-eensmeneeeee ee anne BES Order GoraciiFOrmes; <2cccecccsccese cess ne sense eee cen wese mene enee enc cme rc ee eae eeeneencetencneee 368 OTST ME ASSCTUEOTIINCS) Scat eee eee ee ee cee ae 380 General conclusions 385 Taxonomic value of the structure of feathers.................-..------------------ 385 Principal modifications of structure useful in taxonomy.................... 386 Relationships of groups suggested or corroborated................-.------- 387 The phylogenesis of birds as modified by morphology of feathers... 390 Bibliography ~........---------------------seeeceeeceeneececeec ee ceseeeecennnenneneennenneeneeannaeescessnesnenenceeaees INTRODUCTION I. OssEect AND SCOPE OF PAPER Although as a class birds have received more attention from nearly all classes of zoologists than any other group of vertebrate animals, their natural classification presents a great many problems diffieult of solution, and no satisfactory phylogenetic arrangement has yet been devised for them. It was with the hope of throwing light on some of the dark places in the taxonomy of birds that the writer attempted the work, the results of which are presented in this 1916] Chandler: Structure of Feathers 245 paper, since it was believed that the comparative morphology of feathers would almost certainly be of some taxonomic value in estab- lishing the relationships of various groups of birds. Since feathers are external and in constant contact with the environment, they would naturally be expected to be among the first structures of the body to feel the influence of environmental changes and shocks, and would still be as liable to change by hybridization, orthogenesis or any other method of evolution, as any of the other structures. There are numerous groups of birds, the taxonomic position and phylogenetic relationships of which have been in very great doubt. As far as possible the feathers of these groups have been studied with the hope that the structure of the feathers would reveal relationships that the structure of the other organs would not, on account of parallel adaptations in the latter. Instances in which the morphology of feathers has been found in this study to throw light on doubtful relationships are numerous, for example, in the case of the Phoeni- copteri, Tinamidae, and Pici. Provided that birds were found to possess constant and peculiar characters in the structure of their feathers, the results of such work would be of high economic importance in the identification of feathers used commercially, and for the confiscation of feathers illegally used in commerce. This belief, in the course of the work, has been amply justified, and already successful diagnoses of unknown feathers have been made for the United States Customs officers in the port of San Francisco. Before undertaking a study of the phylogenetic modifications in feathers, a careful study was made of the structural modifications of feathers in the different parts of the plumage of a single repre- sentative bird, namely, Circus hudsonius (Chandler, 1914). It was discovered that certain general modifications found in this bird in the structure, not only of different feathers, but of different parts of the same feather, occur almost uniformly throughout the class. A diseussion of the typical structure of various kinds of feathers, with a consideration of the more important modifications of struc- ture correlated with color production, constitutes the first part of this paper, while the second part deals with special group characters, modifications and peculiarities, arranged in systematic order. No attempt has been made to make a systematic study of the morphology of any feathers except those of adult birds—i. e., of teleoptiles. 246 University of California Publications in Zoology Vou. 138 II. AcKNOWLEDGMENTS To Professor C. A. Kofoid, of the University of California, under whose direct supervision this work was carried on, the writer is especially grateful for his very valuable advice and suggestions, and for his aid in the preparation of this paper. The writer is indebted to Dr. Joseph Grinnell, of the Museum of Vertebrate Zoology of the University of California, for free use of the specimens in the museum. He also wishes to express his appre- ciation of the generous supply of material for study by the American Museum of Natural History in New York, and the United States National Museum in Washington. Grateful acknowledgments are due to Dr. W. T. Hornaday and Mr. Lee 8. Crandall of the New York Zoological Park for saving and sending molted feathers which could not readily be procured from museum specimens. Other material was procured from the Memorial Museum in Golden Gate Park, San Francisco, through Mr. W. G. Blunt of the Natural History department. The writer is further indebted to the California Academy of Sciences in San Francisco, for the use of its collection of water birds, and to the Bentley Ostrich Farm of Oakland, California, for the supply of ostrich feathers, and assist- ance in the examination of living birds. Ill. Huisrorican The first thorough and reliable work on feathers was done by Nitzsch, a German ornithologist. This work was edited and pub- lished by Burmeister, and later translated into English and published in the Transactions of the Ray Society in 1876, a few of the miscon- ceptions of the original author being rectified in the process. This work, though dealing primarily with pterylography, contains the first approximately accurate account of the structure of feathers to be found in the whole literature of the subject, and may justly stand as a masterpiece. Following Nitzsch, a number of works on the development and structure of feathers appeared, among which may be mentioned especially Clement (1876), Studer (1878), Jeffries (1884), Klee (1886), Davies (1889), and Strong (1902) ; and, more particularly on structure, Wray (1887b), Pyeraft (1893), and Mascha (1904). Many other less general but highly valuable papers 1916] Chandler: Structure of Feathers 247 on the structure and development of feathers have appeared, but need not be mentioned here. Throughout the literature, no general attempt has been made to use differences in the morphology of the minute structures of feath- ers as taxonomic or diagnostic characters. In a few cases where feathers differ macroscopically and obviously from the usual type, as in cassowaries and penguins, they have been considered as of taxonomic value, and the presence or absence, or degree of develop- ment, of the aftershaft has been so used. Jeffries (1884) realized that differences in the microscopic structures of feathers existed in different groups of birds, as shown by the following quotation from the paper cited: ‘‘The minute structures of these (wing and tail feathers) vary in different groups of birds, as I have myself observed, and has, I believe, been pointed out by Schroeder, though I have not seen his paper.’’ In Newton’s Dictionary of Birds, under the article on ‘‘Feather’’, is a similar statement as follows: ‘‘Cilia which are not furnished with hooks frequently have shapes which may possibly prove to be characteristic of different groups of birds’’. The only actual investigation of group differences in the micro. scopie structure of feathers was done by Mascha (1904). His work is accurate and suggestive as far as it goes, but he dealt only with the remiges of a very limited number of species, and, as would be expected from such a restricted survey, he missed entirely the taxo- nomic value of certain of the most characteristic features in the microscopic structure of feathers, and contributed but little towards our knowledge of the systematic and phylogenetic value of feather structures. In recent years considerable work has been done by zoologists in the study of the morphology and the taxonomic value of other integumentary structures of vertebrates, and their results point to the fact that such structures, though constantly in contact with the environment, and subject to more external influences than any other organs of the body, nevertheless possess phylogenetic characters which are remarkably constant and easily recognizable. The work of Toldt (1912) on the hair of mammals, like Mascha’s (1904) work on feathers, though only a beginning, is careful and accurate as far as it goes, and is highly suggestive in that it points the way to a field which is still almost untouched. Work along similar lines on the seales of reptiles has been done by Stehli (1910). His study was rather a general treatise on a few types, designed 248 University of California Publications in Zoology (Vou. 138 in part to show the relation of the scalation to the segmentation of the musculature, but his description and figures indicate that modifi- cations of taxonomic value undoubtedly exist in the scales of reptiles. The scales of fishes have received more attention than any of the structures in other groups which in a general way are analogous, and these are the only integumentary growths, the morphologic modi- fications of which have heretofore been actually applied to taxonomic and phylogenetic problems. A series of papers by T. D. A. Cockerell (1909-1913) deals with the actual taxonomic application of scale structures, and gives keys to families and genera based on these char- acters. Cockerell (1911le and 1912) has shown that the scales of coeciliids also show characters which are of value in classification. In view of the fact that all these integumentary structures of vertebrates are homologous, or at least in a general way analogous, to each other, and that investigations of them, in a general way, present similar problems, and are governed by the same limitations, and in fact frequently overlap each other, it seems to the writer that a common name should be applied to the study of them. For this study, which shall include the study of the development, morphology, and phylogenesis of vertebrate scales, hair, and feathers, and any other homologous or analogous structures, the writer wishes to sug- gest the name Epiphyology (based upon emipverv, to grow upon) as a general term for the ‘‘study of outgrowths’. In creating this term it is admitted that the formation is not perfectly valid etymologically. TV. NoMENCLATURE AND DEFINITIONS It is unfortunate that in the literature of feathers there has been a very notable lack of uniformity in the use and meaning of terms, resulting in no little confusion and inconvenience, considerably more so among German writers, however, than among others. After a careful study of the history and usage of the nomenclature of feathers, the writer has selected a terminology which, taking all points of view into consideration, seems to be the most logical and widely applicable. These terms have been selected with regard (1) to the general usage, (2) to convenience, (3) to priority. It seems advisable to give a list of the terms here used to describe feathers, with their definitions, and in the case of terms which have been used inac- curately, the names of some of the authors who have used them in the sense here accepted. The more important synonyms are also given, 1916] Chandler: Structure of Feathers 249 with their chief adherents in the case of terms not commonly used as alternatives. In a few cases new terms had to be coined, or old ones re-defined, but it is hoped that the terminology here used will meet with the approval of other workers, and come into general Aa ZA ----in.v. a aftersh. -- ---- Sage Fig. A. Typical contour feather. Abbreviations: aftersh., aftershaft; cal., calamus; down. str., downy structure; in. v., inner vane; out. v., outer vane; pen. str., pennaceous structure; sh., shaft. use, a thing which would go a long way towards establishing sim- plicity and clearness in the description of feathers and their strue- tures. The terminology suggested is as follows: TERMS OF ORIENTATION. In speaking of a feather, or any of its structures, “dorsal” and “ventral’’ are used as intrinsic terms, i. e., with refer- ence to the feather itself, regardless of its position on the bird, dor- sal meaning, therefore, the side of the feather which is usually exposed, or that opposite the superior umbilicus, which is considered to be upon the ventral side Lateral is used with reference to the dorso- 250 University of California Publications in Zoology (Vou. 13 ventral lines as here defined. Inner and outer, as applied to vanes, are used to mean respectively the vanes adjacent to and away from the next overlapping feather. Proximal and distal, as applied to entire barbules or vanules, refer respectively to those on the side of the ramus nearer to and away from the base of the feather. In all other cases, proximal and distal are used intrinsically with reference to the structure to which they apply; for example, the proximal part of a barb is the less remote, and the distal part the more remote, from the junction with the shaft. Inner and basal are sometimes used synony- mously with proximal, while outer and terminal are likewise used in place of distal. Contour Fraruers (fig. A). The feathers which form the contour of a bird’s body, growing only in the pterylae, and always with well-developed shafts and calami. Eyelashes, ear-coverts, etc., and the semi-plumes of Nitzsch (1867) are considered as modified contour feathers. German synonym: Konturfedern. PLUMULES. Small, downy feathers, more or less concealed, and with shaft never highly developed. They grow either in the apteria or pterylae, or both, often arranged in a definite manner around the contour feath- ers; absent in some birds (Nitzsch, 1867; Coues, 1884; Evans, 1899, et al.). Synonym: down or down feathers, a term for plumules which is objectionable on account of its loose application not only to plumules, but to any feather or part of feather possessing downy structure. Ger- man synonyms: Dunen (Gadow, 1891); Flaumfedern (Wiedersheim, 1909). FitoptumMeEs. Degenerate, hairlike feathers growing at the base of contour feathers, composed of a slender quill not differentiated into shaft and calamus, and much reduced vanes, the latter usually consisting of only a few barbs and barbules at the extreme tip. German synonyms: Haar- federn, Fadenfedern. Down, or Downy Structure (fig. A). That type of feather structure which is produced by elongated, filamentous barbules, as opposed to a pen- naceous structure (fig. A), which is produced by differentiated distal and proximal barbules or modifications of them, i. e., pennaceous bar- bules, as here used. German synonym: Dunen. Quit. (fig. A). The main stem of a feather, including both shaft and cala- mus (Coues, 1884; Beebe, 1906, et al.). Synonyms: main stem (Nitzsch, 1867), scapus (Nitzsch, 1867; Sundevall, 1886; Pycraft, 1893), primary quill (Mascha, 1905). German synonyms: Kiel (Gadow, 1891), Haupt- kiel (Mascha, 1904). Catamus (fig. A). The hollow basal portion of the quill, proximal to the superior umbilicus. Synonym: barrel (Newton, 1899), tube (Nitzsch, 1867). German synonym: Spule, of general use. Inrertor Umeriiicus. The proximal end of the calamus, where the papilla finally closes after the maturity of the feather. Superior Umpriticus. The pore at the distal end of the calamus, at the junc- tion of shaft and aftershaft, or, in some feathers, where the inner and outer vanes meet. Synonym: umbiliciform pit (Nitzsch, 1867; Newton, 1899). German synonym: Nabel (Gadow, 1891). 1916] Chandler: Structure of Feathers 251 Suarr (fig. A). The portion of the quill distal to the superior umbilicus upon which are borne the vanes. Synonyms: rhachis, used generally as an alternative in heavier scientific writing. German synonym: Schaft, of general use. AFTERSHAFT (fig. A). The ventral counterpart of the shaft plus its vanes (“plate’, see below), springing from the ventral lip of the superior umbilicus, sometimes vestigial or absent. Synonyms: hyporhachis, used as is rhachis for shaft; accessory plume (Sundevall, 1886). German synonyms: Afterschaft, Nebenschaft (Gadow, 1891); Afterfeder (Studer, 1878), Afterschaft, only its shaft (Studer, 1878). Puatr. A convenient term used by Mascha (1905), to designate the shaft with both its vanes. Synonym: vexillum (Clement, 1876). German synonym: Flache (Mascha, 1904). VANE (fig. A). That portion of the feather borne on one side of the shaft, composed of barbs, usually with barbules. Inner vane, that which is overlapped by the outer vane of the adjacent feather. Synonym: vexil lum, web, common alternatives (the vexillum of Clement, 1876, equals plate), pogonium (Sundevall, 1886). German synonym: Fahne, of general use. Bars (fig. B). A ramus or primary branch of the shaft plus its barbules (Beebe, 1906; Headley, 1895, et al.); has been loosely used by many authors to designate either the ramus alone, or the ramus with its barbules. German synonyms: words used for ramus also loosely used for barb; also Fiedern erster Ordnung (Haecker, 1896); Fiedern (AhI- born, 1896). ‘-- dist. van. 1 pei ee ern — Yi, -», ridge.) , b.----—— pith. {" ' 4 1 — ! <- prox. van. Fig. B. Proximal half of barb of duck. Abbreviations: dist. v., distal vanule; prox. van., proximal vanule; 7., ramus; vil., villi. Ramus (figs. B and C). A primary branch of the shaft, forming the main stem or lamella of a barb, upon which are normally borne barbules. Synonym: barb (see above); secondary quill (Mascha, 1905). German synonyms: Aeste (Nitzsch, 1867; Gadow, 1891; Wiedersheim, 1909); Strahlen (Studer, 1878; Davies, 1889); Fiederlamelle (Ahlborn, 1896); Fasern (Cuvier, 1809); sekundare Kiele (Mascha, 1904). 252 University of California Publications in Zoology (Vor. 138 Fig. C. Cross-section of hypothetical barb. Ab- breviations: dist. 1., distal ledge; d. ridge, dorsal ridge; gr., groove for Sf ee r. insertion of distal barbule; prox. L., OD ieee dist. l. proximal ledge; v. ridge, ventral ridge. seeecese pith. Verran River (figs. B and C). A horny keel on etna: prox. | ENTRAL RipeE (figs. B an - orny kee the ventral side of the ramus, usually nar- row, though sometimes very highly developed (Strong, 1902; Mascha, 1905). German syno- nym: Hornleiste (Mascha, 1904). LrepGE (fig. C). Longitudinal grooved ledges on the lateral sides of some rami, into which Fie. C the barbules fit and which tend to hold them in place. Indefinitely called “ridges” or “longitudinal ridges’ by Mascha (1905). German synonym: Gesims (Mascha, 1904). BARBULE (figs. D, E and F). A branch of a ramus, collectively forming the vanules. Pennaceous barbules are those which are differentiated into a proximal and distal series which interlock by means of hooklets, unless the structure has been secondarily simplified. The proximal barbules (fig. D) are those which are borne on the side of the ramus nearest the base of the feather. The distal barbules (fig. E) those which are borne on the side nearest the tip. Downy barbules (fig. F) are those which are relatively long and filamentous, with no interlocking device. Synonym: radius, a common alternative; tertiary fibers (Mascha, 1905); hook fibers (= distal barbules) and curved fibers (= proximal barbules) (Mascha, 1904). German synonyms: Strahlen (Nitzsch, 1867; Gadow, 1891; Wiedersheim; secundare Strahlen (Studer, 1878); Fieder- chen (Ahlborn, 1896); tertiare Fasern (Mascha, 1904); Hakenfasern (= distal barbules) and Bogenfasern (= proximal barbules) (Mascha, 1904). ---- v. ridge. 5 SSS Fig. D. Diagrammatic distal barbule. Abbreviations: b., base; d. cil., dorsal cilia; 7l., flange; h., hooklets; n., nucleus; pen., pennulum; v. cil., ventral cilia: v. t., ventral teeth. Fig. E. Diagrammatic proximal barbule. Abbreviations: b., base; d. sp., dorsal spines; 7l., flange; n., nucleus; pen., pennulum; v. t., ven- tral teeth. 1916] Chandler: Structure of Feathers 253 Fig. F. Diagrammatic downy barbule. Abbreviations: attach., attachment with barb; b., base; internod., internode; nod., node; pen., pennu- lum; pr., prongs; vil., villi. VANULE (fig. B). A new term here used to designate collectively all the barbules of either the distal or the proximal series, bearing the same relation to the barb that the vane bears to the feather plate. Hitherto referred to only as the “‘vane” of the barb. Base (figs. D, E and F). The proximal portion of a barbule, which is more or less lamelliform; in distal barbules the portion proximal to the hooklet cells, in proximal barbules the portion proximal to the bend occurring just beyond the ventral teeth, and in down barbules tne short flattened portion at the junction with the ramus. Synonym: lamella (Newton, 1899). Otherwise referred to only by descriptive phrases. German synonym: Anfangsteil (Mascha, 1904). PENNULUM (figs. D, E and F). A new term here used to designate the more or less attenuated distal portion of a barbule, bearing the hook- lets and cilia, or, in the case of down, the nodes. Synonym: tip (Chand- ler, 1914). Otherwise referred to only by descriptive phrases. German synonym: Endteil (Mascha, 1904). FLANGE (fig. D and E). The thickened dorsal edge of the bases of pen- naceous barbules; generally recurved in proximal barbules, and fre- quently so in distal barbules also (Wray, 1887). Synonym: recurved margin (Strong, 1902), and other descriptive phrases. German syno- nym: Rinne (Mascha, 1904). DorsaL Sprnes (fig. E). Recurved spines on the flange of proximal bar- bules, opposite the ventral teeth. Synonym: toothlike processes (Mascha, 1905). German synonym: Zahnforsatze (Mascha, 1904). BARBICELS (figs. D and E). Outgrowths of the cells of the linear series form- ing pennaceous barbules, usually projections from the anterior dorsal or ventral corners of the cells. Used by Nitzsch (1867) and Pycraft (1893) to designate cilia only, but more commonly used in the broader sense here accepted. Synonym: cilia (sometimes used in this broad sense). German synonyms: Hakchen, Wimpern, of general use. Hooxtets (fig. D). Ventral barbicels which are strongly hooked at the tip, occurring only on the proximal portion of the pennulum of distal barbules. Hooklet-bearing cells never possess dorsal barbicels. German synonym: Hakchen, (Gadow, 1891; Nitzsch, 1867); Haken (Mascha, 1904). Cina (fig. D). Pennular barbicels, dorsal or ventral, occurring on distal barbules distal to the hooklets, and often on proximal barbules of the outer vane of highly developed feathers. German synonym: Wimpern (Nitzsch, 1867; Mascha, 1904); Hakchen (Studer, 1878). 254 University of California Publications in Zoology {Vou. 138 VENTRAL TEETH (figs. D and E). Anteriorly projecting, ventral, basilar bar- bicels of both distal and proximal barbules of nearly all birds, often lobate or leaflike in distal barbules, usually toothlike in proximal bar- bules. Synonym: toothlike processes (Wray, 1887); ventral lobes (Mascha, 1905). German synonym: ventrale Lappen (Mascha, 1904). FLEXULES (pl. 17, fig. 10e). A new term used to designate the curved bar- bicels occurring on the dorsal edge of the bases of distal and proximal barbules of the trunk feathers in some groups of birds (see p. 272). Hitherto apparently unknown. Nopes (fig. F). The junction of the cells of the pennulum of down bar- bules, usually characterized by swellings or outgrowths of some sort. Prones (fig. F). Short, spiny outgrowths at the nodes of the down of many birds, differing from other barbicels in that three or more may occur on the distal end of a single cell, whereas there are never more than two cilia or other kinds of barbicels on a single cell. V. MeruHops After experimenting with various methods of preparing feathers for microscopic study, especially the barbules, it was found that in most cases the examination of dry mounts of barbs and barbules gave entirely satisfactory results. This was at the same time so simple, and took so little time in preparation, that it was possible to examine the microscopic structures of the feathers of a very large series of birds, and thereby to determine with considerable precision the constancy and uniformity of characters in various groups. The barbs were first studied under the microscope with their vanules intact. The vanules were then spread backward in order to separate the barbules for individual study, this bemg done by merely drawing the barb, tip first, between the thumb and forefinger. With a scalpel some of the barbules from each vanule were scraped off from the region of the barbule which it was desired to study, and mounted dry under a cover glass. In this way a considerable number of individual barbules could be separated, and as they would lie in all sorts of positions, their general form could be studied readily from such a preparation. The morphology of heavily pig- mented structures could be studied more easily when mounted in balsam. In some eases also barbules were mounted in balsam in order to determine whether certain appearances were due merely to pigmentation, or to structural modification, and to determine the effect of oils of low refractive index on color-producing mechan- isms. The methods of treating individual birds and groups of birds to determine their epiphyologic characters will be discussed at the beginning of Part II. bo OV oO 1916] Chandler: Structure of Feathers Part I GENERAL MORPHOLOGY J. PLUMULES 1. Unspecialized Plumules a) Occurrence and Distribution—As remarked above, from a general survey of the feathers of a large number of species of birds, it is evident that certain generalizations regarding feather structures may be made. It is the intention of this portion of the paper to describe the general characters of various kinds of feathers, and to discuss briefly the range of modifications exhibited by them and their several parts. Plumules are small downy feathers which are usually completely covered by the contour feathers in adult birds. Their distribution on the body differs a great deal in different kinds of birds. They may be (1) evenly distributed over the whole body, both in the ap- teria, and in the pterylae between the contour feathers; (2) sparsely or unevenly scattered over the whole body; (3) confined to the apteria; (4) confined to the pterylae (only in Tinamidae) ; or (5) absent entirely. The table on page 256 shows the nature of the distribution of plumules in the various groups of birds, the data being derived from Gadow (1891), Beddard (1898), and others. In looking over this table it seems evident that a uniform dis- tribution of plumules is to be considered a primitive condition, yet in all of the ratite birds, which have usually been considered the most primitive, they are absent entirely. It seems to me that this may be explained in one of two ways: either that the ratite birds have degenerated from a higher type and have lost their plumules concomitant with a simplification of their contour feathers from a pennaceous to a downy type, or that the ratite birds show a condition of plumage more primitive than any other birds, and that in the course of evolution the downy contour feathers of these birds devel- oped along two separate lines, one leading to the soft, fluffy, almost shaftless plumules in both pterylae and apteria, the other to the highly specialized contour feathers in the pterylae only. Further 256 University of California Publications in Zoology \Vor.18 Group Struthioniformes .... Crypturiformes .......... Apterygiformes ...... Spheniseiformes ...... Colymbiformes ........ Procellariiformes .... Ciconiiformes Steganopodes ........ ATO CAC: seccsscececcawcaces rlconiaene Phoenicopteri ........ Anseriformes ............ Falconiformes -.. Galliformes 5 Opisthocomi .......... Mesaenatides ........ Gruiformes e..---------. Charadriiformes Laro-limicolae Alcidae Cuculiformes PSICtaCie ee sees Cuculi Coraciiformes Coraciaey = Alcedinidae ...... AN others S tri ges ees eeacessee Caprimulgi ............ Micropodii ..... ons Trochilidae ........ Colii and Trogones Passeriformes and TSANG (i eae Pere ee EE es DISTRIBUTION OF PLUMULES wo 2 ea 9 8 BO ES s ceiee Gea! Ze fe = Be sia & + $ pul xe - + + rite a mn eA + fer eee +or+ eee + + + + + Lee Absent or sparse + in apteria Pterylae only +, very large , or rudimentary | +, rudimentary in Diomedea +, or rudimentary + variable , well-developed ~—, rudimentary in a few genera , - in Pandion and Cathartidae large or small + ate +, + variable, usually present + + small or rudimentary +, large —, or rudimentary +, often rudimentary —, rudimentary in Aluco small or — +, not highly developed evolution, if this hypothesis be true, resulted in the segregation of contour feathers into tracts, and the reduction of plumules, first between the contour feathers, and finally on the whole body, culmi- 1916] Chandler: Structure of Feathers 257 nating in the condition found in passerine birds and allied forms. There is further evidence in support of the latter alternative in that, so far as I have been able to discover, filoplumes also are totally absent in the Ratitae, while, so far as is known, they are present, associated with contour feathers, in all other groups of birds. b) Structure——In general structure plumules are remarkably con- stant, not only on different parts of the body, but also throughout the entire class of birds. On different parts of the body of an individual the only appreciable modification is in size, the plumules of the larger apteria usually being the largest. The quill in plumules is invariably short and inconspicuous. The calamus, which is hollow and barrel-shaped, having a more or less inflated appearance, is usually entirely imbedded in the skin. The shaft is always short and poorly developed, very soon breaking up entirely into barbs in a more or less fan-shaped manner, and it is plainly evident, in the majority of cases, that the thin, flat, more or less subtriangular shaft is to be looked upon merely as a basal coalescence of the barbs. The plumules possess an aftershaft in groups which are characterized by the presence of an aftershaft in the contour feathers, even if only rudimentary in the latter. Since many of the birds which lack an aftershaft are also devoid of plu- mules, it is rare to find the latter with a single shaft. Owls, which lack an aftershaft on the contour feathers, with the exception of a rudimentary one in Aluco, have plumules with only one shaft, a dense cluster of barbs springing from the sides and ventral lips of the superior umbilicus. Pelecanus was stated by Nitzsch (1867), and restated by other authors, to have plumules with no shafts. This is not strictly true. Pelecanus erythrorhynchus has plumules with two fairly well-developed shafts, equivalent to each other, about 1.6 mm. long, which possess a brown pigment, the rest of the plumule being unpigmented. In Phalacocorax (P. penicillatus), how- ever, the plumules almost Jack a shaft, the latter structure being so rudimentary that it is actually wider than long. In the Tetrao- nidae and some other galliform birds, where the aftershaft of the contour feathers has its shaft very highly developed with two dis- tinct vanes, the plumules have the shaft likewise developed. In Lophortyx, for instance, both shafts of the plumules reach a length of six or seven millimeters, in spite of the small size of the feathers. As pointed out by me (1914), the shaft and aftershaft of plumules, 258 University of California Publications in Zoology (Vou. 18 when both present, are nearly equivalent in size and are practically indistinguishable from each other either by structure or position. The rami of plumules are extremely long, slender, filamentous, and very numerous, the cellular structure not apparent, and with no edges or dorsal or ventral ridges. The barbules are always of downy type, and have the same structure as the downy barbules of the contour feathers, being of the type found on the aftershaft when this differs from the downy portion of the feather plate, as in gallinaceous birds. As a rule the downy barbules of the plumules are longer and more numerous than those of the contour feathers of the same species, but the difference is often inappreciable. In some genera, e. g., in Circus, the barbules of the plumule are more slender than those of the down of contour feathers, and more flexible. The result of the close setting and great length of both rami and barbules, and of their slender, flexible nature, characteristic of most plumules, is a very dense, cottony structure which eminently serves its purpose as a water-proof, heat-insulating covering for the body, as pointed out by me (1914). It is significant that plumules, almost without exception, reach a high development and have a uniform distribution in all water birds. 2. Powder-down Occurring as a frequent modification of plumules is the so-called ‘‘nowder-down’’, a description of which was given by me (1914) in the case of Circus hudsonius. Powder-down, according to Gadow (1891), oceurs in the following birds: All Ardeae, Balaeniceps, Rhinochetus, Eurypyga, Mesites, Tinamidae, a few Falconiformes, some Psittaci, Podargus, Leptosoma, Coracias, and only one passerine genus, Artamus. I have also found it in the burrowing owl, Speotyto cunicularia. Although sometimes found scattered promiscuously among the plumules, as in Gypaétus and many parrots, powder-down is usually found in more or less well-defined patches. As Gadow (1891) sug- gests, the occurrence of powder-down in such diverse groups of birds, and the wide variety of situations in which it is found on individuals, make it appear that typical plumules, at different times and in different groups, may be modified into powder-down, as the result of some unknown stimulation. (ii we) 1916] Chandler: Structure of Feathers 2 3. Oul-gland Feathers In the majority of birds the oil-gland, occurring on the rump, is furnished with a circlet of feathers at or near its apex, while in others the sides of the glandular swelling are furnished with small feathers and the apical circlet is missing. The presence or absence of this circlet has been used extensively as a taxonomic character. When present the feathers constituting the circlet are of modified plumule type. In Circus hudsonius, for instance, the shaft is entirely missing, the calamus splitting immediately imto several divisions, which further split into barbs (see Chandler, 1914). There is evi- dence, in Circus at least, that the feathers in the cirelet are definite in number. 4. Nestling Feathers Although no thorough systematie study of the microscopic struc- ture of restling feathers has been attempted, a brief survey of a few diverse types brings out some interesting facts. The highest development of nestling feathers is displayed in ostriches, in which there is a well-formed calamus. The distal portion of a number of the barbs is more or less expanded and flattened (pl. 18, fig. 2d), giving the plumage of the chick a very coarse, bristly appearance. The barbules are numerous, and similar in structure to those of the teleoptiles, only very much shorter. In rheas, as in ostriches, barbules are borne only on the basal portion of the barbs, the tips being hairlike. In earinate birds the structure of the down barbules of nestling feathers is nearly always less specialized than that of the down of adults. In penguins the minute structure of the neossoptiles or nestling feathers is exactly similar to that of the down of the tel- eoptiles (pl. 34, fig. 96), the barbules being filamentous with short, sharp prongs at the nodes (see Studer, 1878). Im ducks, e. g., Anas platyrhynchos, the nestling down differs widely from that of the adults (pl. 35, fig. 104), being exactly similar in form to the down of penguins. The barbules are short and filamentous, with a series of prongs at the nodes, those nearer the tip of the barbules being more prominent than those near the base (compare pl. 35, fig. 104, with pl. 34, fig. 96). The yellow color so characteristic of ducklings is due entirely to structural interference of light. In rails, although the adult down is widely different from that of either ducks or penguins, the nestling down is very similar to that of both these birds, the char- 260 University of California Publications in Zoology ‘Vou. 18 acteristic black color being due to a uniform distribution of pigment, even in the prongs, thus differing markedly from the adults. The nestling down of Phalacocorax is hardly distinguishable from that described for the other water birds, some of the feathers being black, due to an even distribution of pigment in the barbs and barbules, a few remaining white. In gallinaceous birds, e. g., Dendragapus, the nestling down is not quite so primitive, the barbules being longer, with slightly swollen nodes and very inconspicuous prongs, but with evenly distributed pigment. From an examination of these few types, it may be safely con- cluded that neossoptiles show a much narrower range of modification in the minute structure of their down than do the teleoptiles, whether plumules or contour feathers. The fact that the structure of adult down in penguins is similar to the nestling down of not only pen- euins, but also of ducks, rails, and cormorants, may be an argument in favor of the primitive nature of the former birds. II. KFmoprLumMeEs 1. Occurrence and Distribution Filoplumes are in some ways the most remarkable modifications of feathers found on birds. Although with a very few exceptions they are excessively slender and very difficult to see with the naked eye, and never developd in sufficient number to be of any possible mechanical use as a covering or support, these inconspicuous feathers are remarkably constant, in some degree of development, in all birds except the ratites. Nitzsch (1867) states that they are probably present in all birds, as he has never looked for them in vain, when the necessary trouble has been taken to find them. This statement, though generally accepted by ornithologists, needs further corrobora- tion. I have been unable to find them in the dried skins of a number. of birds, though they may have been present, but so reduced as to be very difficult to discern amongst the other feathers. Such an apparent lack of filoplumes occurred in two species of Pelecanus (P. erythrorhynchus and P. californicus), in Aechmophorus occidentalis, and other species. It may be stated positively that they are not present in ostriches or cassowaries, and probably not in any of the ratite birds. Nitzsch (1867) described filoplumes from cassowaries, stating that they were coarse, much flattened structures, very differ- ent from the filoplumes of other birds, and this has been widely quoted by other authors. Thorough examination of ostriches, both 1916] Chandler: Structure of Feathers 261 young and adult, as well as of the back and breast of a cassowary, failed to show any filoplumes whatever. What Nitzsch very probably mistook for filoplumes are the tips of feathers just growing out, which give exactly the appearance described by him for filoplumes. When present these anomalous feathers are always associated with contour feathers, though not always accompanying all feathers of this type; in Circus hudsonius, for instance, they could be found only in the dorsal, lumbar, and caudal tracts. When present they grow out in groups from the dorsal side of the socket of the contour feather with which they are associated. There may be only one or two of these in a group, or as many as ten in some water birds, ac- cording to Nitzsch (1867). In Circus hudsonius there are from five to eight in a bundle, no two in a bundle usually being of the same length. 2. Structure As shown by Pyeraft (1909), filoplumes are really degenerate feathers, only the barbs of the extreme tip of the feather becoming attached to the slender shaft. The other barbs are formed more or less perfectly, but through a defect in development never become attached to the shaft. Nitzsch reports a case in which some downy barbs and barbules were found near the base of the filoplumes in a specimen of ‘‘Gallus bankwa domestica.’’ It is very probable that this was an abnormal case in which the development was not arrested as usual, or it may have been a filoplume which had not completed its development, and had not yet lost its deciduous barbs. Unlike either plumules or contour feathers, filoplumes never have the quill divided into calamus and shaft, the base not becoming hollow and pithy, and the superior umbilicus being absent. The only differ- entiation at the base of a filoplume is a slight widening and flattening (see Chandler, 1914, pl. 16 fig. 2). As a rule, full-grown filoplumes have exceedingly slender shafts, often ridged and pitted to give a silvery appearance like a fiber of silk, and they are naked except at the extreme tip, where a few rudimentary barbules are borne directly on the shaft, or on two or three rami which may be given off. In some species they are pigmented, e. g., in the robin, Planesticus migratorius, while in closely allied species, e. g., the bluebird, Sialia mexicana occidentalis, they have the typical, unpigmented, silvery color. 262 Unversity of California Publications in Zoology (Vor. 138 Although usually entirely covered by the contour feathers, filoplumes are occasionally developed to an extraordinary degree. In many passerine birds they may be seen with a hand-lens project- ing beyond the tips of the contour feathers on the nape, while in other closely allied species they may not be exposed at all. In Planesticus migratorius and Sialia mexicana occidentalis, for example, they are plainly visible in the unruffled plumage, while in Hylocichla guttata they are not exposed at all. In many genera of Pycnonotidae they are long and hairlike, giving a conspicuously hairy appearance to the plumage in the region of the nape and upper back. The only place in which I have found filoplumes really conspicuous is in the plumage of cormorants, more or less in all of the species examined, especially on the neck and upper back, although to some extent on the breast, belly, and rump as well. In these birds many of the filoplumes are long and largely exposed, and have the vanes developed to a very unusual extent. In males they are pure white and show up conspicuously as white streaks against the deep greenish- black color of the contour feathers, while in females they are buffy brown and inconspicuous against the brown plumage. Although their development is very variable, some of them haye barbs borne on the terminal four-fifths of the shaft, though there are only about 15 per centimeter on each side, i. e., they are 0.6 mm. or more apart. They are set at a very sharp angle with the shaft, so that they make narrow but fairly dense vanes. The barbs bear very numerous barbules, about 35 per millimeter on each side. They are of a filament- ous downy type, but only 0.02 mm. long, and not spread apart to form broad vanules. Although the barbules of the plumules of these species are filamentous, with practically no indication of nodes except at the extreme tip, the nodes on the barbules of the filoplumes are characterized by well-developed sharp prongs, thus resembling the nestling feathers. Though far from what would be expected, filo- plumes are by no means conspicuously developed in allied families of Steganopodes; in fact, I have searched in vain for them in dried skins of Pelecanus erythrorhynchus and P. californicus, Plotus an- hinga and Phaéthon longicauda. Since filoplumes occur in the most diverse group of birds, and yet attain such a variable degree of development in birds within the same order, it is a natural presump- tion that they are of some use in the economy of nature, and are not 1916] Chandler: Structure of Feathers 263 merely vestigial or rudimentary structures. No suggestion of a pos- sible use has yet been made. III. Contour FEATHERS Under contour feathers, in their various forms and modifications, may be included practically all of the diverse kinds of plumage ordi- narily displayed on the body of a bird. In this category come all remiges, rectrices, coverts, and exposed body-feathers, except in a few instances where filoplumes or plumules are exposed, as in cormor- ants and on the neck of Pelecanus respectively ; also ear-coverts, eye- lashes, rictal and other bristles, and all sorts of ornamental crests and plumes, and other modified feather structures, such as the brush of a turkey, the ‘‘wires’’ of some birds of paradise, the lyre of Menura, ete. Their variety of form is almost limitless, yet they are all modifications of the same fundamental structure. A discussion of the various important types of feathers in a typical bird of flight has been made for Circus hudsonius by me, (1914) and it is only necessary here to generalize on the conditions found there, and show along what lines phylogenetic modifications of this type have taken place in the whole series of birds. 1. Remiges a) Shaft—The most highly specialized feathers, those in which the structure reaches its height of perfection, are the remiges, espe- cially the primaries, of strong-flying birds. These feathers, in all flying birds, have a well-developed quill, differentiated into a hollow calamus and a stiff shaft which is more or less rectangular in cross- section, and usually has a groove running along the ventral side, generally quite pronounced at the superior umbilicus and becoming obliterated towards the tip of the feather. The condition of the groove varies to a considerable extent in different groups of birds, in some being broad and shallow, in some narrow and deep, and with all gradations between in others. In the remiges of ostriches the ventral groove of the shaft reaches its maximum size, the shaft in this case being in the form of a half-cylinder, convex above and concave below, while in some of the higher birds, e. g., Coccyzus, there is no groove whatever. These facts at first glance would indicate that a large, wide-open ventral groove is a primitive character, that the absence 264 Unwersity of California Publications in Zoology (Vou. 18 of a groove is a specialized condition, and that the condition of the groove in the shaft could be used to some extent as a gauge of specialization. This, however, does not hold, since a wide variation can be found, not only within a single group, but in the different feathers of a single species. In less specialized wing quills of a female ostrich, for instance, the shaft has a totally different ap- pearance from that found in the plumes of the male; in the former the shaft is convex above and below, with only a narrow, insignificant groove. In Coccyzus, as mentioned above, there is no ventral groove, while in Geococcyx, of the same family, there is a broad, shallow groove. In the penguins there is not only no groove, but a median keel is developed both above and below on the very broad, flat shaft. In cassowaries, where the remex quills are reduced to bare, stout spines, there is no groove, and the shaft is subcireular in cross-section. Aftershafts are never developed on remiges. b) Vanes and Barbs.—The vanes of remiges of flight birds are never quite equal, the outer vane always being narrower than the inner, very conspicuously so on the outer primaries, often subequal on the inner secondaries. In many of the best birds of flight, espe- cially those which soar and glide to a considerable extent, there is a further modification of the vanes of some of the outer primaries, in that more or less of the distal portion is narrowed down or ‘‘incised’’ so that the tips of these feathers, when the wing is spread, are separated from one another like spread fingers. In the columbid genus Drepanoptila, the feather plate is bifurcated, there being dis- tally two shafts and four vanes. This anomalous condition, character- istic of the trunk feathers of other genera of the same group of Columbidae, must be regarded as a recent, heritable mutation. Usually more or less of the basal portion of the vanes of remiges, as well as of other contour feathers, is downy in character, though often the innermost portion of even the most basal barbs may have pennaceous or transitional barbules, a larger and larger portion be- coming downy as the superior umbilicus is approached (fig. A). In flightless birds various kinds of reduction of the vanes of remiges takes place. In ostriches the remiges are developed in the male as ornamental plumes, in cassowaries they are reduced to stiff, bare spines, with the vanes absent entirely, while in penguins and most other flightless birds they are reduced to the condition of the trunk feathers, and are barely, if at all, distinguishable from them. oO 1916] Chandler: Structure of Feathers 26 Although the narrowness of the outer vane in the primaries is brought about partially by an actual shortness of the barb, it is accentuated by the relatively narrower angle which the barbs of the outer vane make with the shaft. In all but the most generalized remiges, there is a tendency for the barbs of the outer vane to be inserted farther apart on the shaft, but at a more acute angle than those of the inner vane. As a rule, the number of barbs per unit of measure changes in a very definite manner, following a mathematical curve analogous to some of those worked out by Pearl (1907) for erowth in the whorls of leaves of the aquatic plant Ceratophyllum. Beginning at the tip there is a slight decrease in number per unit of measure, then a very slowly accelerating increase for the greater length of the feather, terminating in a very quickly accelerating in- crease as the superior umbilicus is approached, accompanied by a transition to a downy form. It is interesting to note in this con- nection that the change in number of barbules per unit of measure on the barbs follows a very similar curve, and probably varies with a similar mathematical equation. The barbs of remiges, with the exception of the meager basal downy structure already mentioned, are always highly developed in birds of flight, consisting of a thin lamelliform ramus bearing highly developed distal and proximal vanules (Fig. B). The pith of the ramus, as shown by Mascha (1904), is composed either of a single dorso-ventral plate of cells, one cell in thickness, or of a network of cells, more than one cell in thickness (Fig. C). Without exception, the rami of the inner vane are narrower than those of the outer, though often almost imperceptibly so. Distal to the notch of the incised primaries this difference is especially notice- able, the rami of the outer vane being often as deep as the shaft, while those of the inner vane are less than half as deep. In the majority of birds where the rami are not as deep as the shaft, there are fine ridges on the shaft from the insertion of the ramus to the ventral edge. As pointed out by me (1914), the deep type of ramus is probably the more primitive condition. The ventral edges of the rami (fig. C) are produced into horny keels, usually with no evident cell structure, known as the ventral ridges (see Pycraft, 1893; Mascha, 1904; and Stubbs, 1910). AlI- though in the great majority of birds this ridge forms only a nar- row, inconspicuous border for the ramus, in a few birds it is extra- 266 University of California Publications in Zoology \Vou. 18 ordinarily developed as a very thin, translucent film, which bends distally and overlaps the following ramus, giving a smooth, glazed appearance to the under surface of the feather which is conspicuous at the most casual glance. It is thus developed in all of the Anseres, (pl. 33, fig. 28a), and in a number of gallinaceous birds, though in the latter it is by no means constant, being present, for instance, in Bonasa, but absent in Lophortyx. The ventral ridge of the outer vanes of some groups of birds, e. g., Anseres, Faleconidae, and some Ciconiae, is further modified by being furnished with irregular villi (fig. C, and pl. 21, fig. 28b) on the ventral edge. The rami of the inner vane always have the ventral edge entire or nearly so. As shown by Mascha (1904), rami are furnished with a lateral ‘‘ledge’’ which is grooved for the reception of the bases of the bar- bules (fig. C). These are much more highly developed and efficient in some birds than in others, often making it very difficult to scrape off the barbules without tearing off with them a part of the barb to which they remain attached. c) Barbules—The interlocking barbules of a typical remex are of four distinct types, the distal and proximal barbules of the inner vane, and the distal and proximal barbules of the outer vane. It is unnecessary here to enter into a discussion of the typical structure of distal and proximal barbules, or of their manner of interlocking. An excellent description of this is given by Pyeraft (1893), and a few additional facts of interest are added by Mascha (1904). There are, however, a number of minor details of structure of both distal and proximal barbules which are almost uniformly different in all birds in the inner and outer vane, although apparently this facet has escaped the notice of all previous observers. As a rule the bases of the distal barbules of the outer vane are longer and relatively narrower than those of distal barbules of inner vanes, but this is not always true, the chief difference lying in the pennula. On the inner vane the pennulum of distal barbules as a rule is longer than it is in the outer vane, with fewer hooklets, but a larger num- ber of cells with cilia (compare pl. 16, fig. 8a, with fig. 8c and see text-figure D). The most conspicuous difference lies in the dorsal cilia on the proximal portion of the pennulum. Almost without excep- tion, distal barbules of the inner vanes of remiges are characterized by the specialized development of the first two (pl. 20, fig. 20a), and often to a less extent of the third, dorsal cilia (pl. 20, fig. 23a). These specialized cilia are developed as stout, conspicuous, lobate, or 1916] Chandler: Structure of Feathers 267 thornlike projections, which are directed more or less distad, 1. e., toward the tip of the feather (see plates). Im the Falconidae they differ from the other dorsal cilia only in being slightly stouter and more thornlike (pl. 23, figs. 36a, 37a, 38a, 39a, 40a); in owls they are well developed but not differentiated from the other cilia (pl. 32, fig. 84a) ; while in a few birds, e. g. trogons (pl. 31, fig. 80a), they are absent entirely. On the outer vane, on the other hand, the dorsal cilia. of the proximal portion of the pennulum are always absent, at least on the first two or three cells; very frequently no dorsal cilia whatever are present. Usually, however, following the proximal two or three cells, rudimentary barbicels begin to appear, and these become more and more pronounced distad, the reverse condition to that found on the inner vane. With the exception of these few details, the structure of distal barbules of both inner and outer vanes is usually alike, and both show the same group characteristics. The proximal barbules (fig. E) of the two vanes are nearly always exactly similar in more or less of the basal portion of the barbs, but in the majority of birds they differ in the more distal portion of the barb, sometimes only at the tip, more frequently in from one-third to two-thirds of the terminal portion. Those of the inner vane, and those which are similar to them on the outer vane, have rather long slender bases, considerably longer than the bases of the distals, a series of three to six ventral teeth of differing degrees of develop- ment in different birds, and more or less filamentous pennula with only very rudimentary barbicels if any at all. With a few excep- tions, notably most of the ciconiiform birds, the more distal proximals of the outer vane differ decidedly from the others in the development of a series of ventral barbicels, these being formed as an increased number of ventral teeth, accompanied by a change in form. In many birds these ventral barbicels, homologous to the hooklets and ventral cilia of distal barbules, are very large and numerous and highly conspicuous, e. g., in gallinaceous and falconid birds (pl. 23, fig. 38c, and pl. 24, fig. 42e). Perhaps the greatest development is that found in Ceryle alcyon (pl. 31, fig. 79a). In many passerine birds, e. g., in all the Tyrranidae, the outer half of the barbs under- goes a very sudden and conspicuous change from plain to barbicelled proximal barbules (compare plate 33, fig. 92d with plate 33, fig. 93a), this sudden transition including a very marked reduction in the size of the base, and a concomitant simplification of the distal barbules, the hooklets of which become obsolete. This change in structure 268 Unwwersity of California Publications in Zoology ‘Vou. 18 produces the fringe, or edge, usually of a paler color, so frequently found on the remiges and coverts of passerine birds. Usually the structure of barbules, except for variations already mentioned, varies but little on different portions of the same barb or of the same feather. At the base of the barb there is a decided shortening of both kinds of barbules, while at the tip the change is in the nature of a loss of the perfection of structure. Usually, also, the distal barbules of the inner vane have the specialized dorsal cilia better developed on the terminal than on the basal portion of the barb. Surveying the entire class of birds, we find that the pennaceous barbules vary considerably in the different orders and suborders, though usually being fairly constant within the lesser groups, except where modified for color production, or other conspicuous effect. Differences occur in size and shape of the bases, position of nuclei, form of pennulum, and nature of all the different types of barbicels. In tinamous alone a most remarkable modification of the typical vanules occurs in the solid secondary fusion of the pennula of the proximal barbules, except at the extreme tip of the barbule, to form a limiting bar parallel to the barb (pl. 25, figs. 49b and e). Though this surprising modification is absolutely characteristic of all tinamous, not only of the remiges, but of all the other pennaceous contour feathers, I have found no suggestion of it in any other birds, and I have been unable to find any reference to it in the literature. 2. Rectrices With this brief survey of the conditions found in the remiges of birds, we may now turn to the other groups of contour feathers. Next to the remiges, the most highly developed feathers of the body, in birds of strong and graceful flight, are the rectrices. The macro- scopic form of the tail and of its individual feathers varies econ- siderably, and the microscopic structure is far more subject to modifi- cations for special functions than it is in the remiges. In normal rectrices, used in flight for steering and balancing, the structure is very similar to that of the inner remiges, and it is interesting to note that in the middle tail feathers both vanes have a type of struc- ture of barbules similar to that characteristic of the outer vane of remiges. In ratite birds there are no specialized rectrices among the Casuariiformes or the Apterygiformes, while in the Struthioni- formes and the Rheiformes the rectrices are large and developed as 1916] Chandler: Structure of Feathers 269 ornamental plumes. In penguins and Colymbiformes they are indis- tinct. In a few birds, e. g., Menura, they are transformed into an ornament, although it is more frequently the upper tail coverts that are modified to produce an ornamental tail. In woodpeckers, swifts, and a number of other birds the rectrices have the plate undeveloped at the tip, and the bare shafts enlarged as stout spines to aid in climbing or bracing against a steep surface. Like the remiges, the rectrices never possess aftershafts. 3. Unspecialized Contour Feathers Passing now to the coverts, we find that in them there is a com- plete transition from the remex type of structure to that found in the contour feathers of the trunk, the greater coverts being more like the former, some of the lesser ones very much like the latter. We may pass at once, therefore, to a discussion of the morphology of the trunk feathers. a) Aftershafts—tThese feathers in the majority of birds are char- acterized by the presence of an aftershaft, and the presence or ab- sence of this structure has been considered of considerable taxonomic importance. The condition of the aftershaft in the various groups of birds is given in the table on page 256. A evreat deal of variation exists, as will be seen, within single suborders or even families. Within the Ratitae there is an extreme variation from a total absence in the ostriches, rheas and Apteryz, to a maximum size, practically equivalent to the main shaft, in cassowaries and emus. Various types of aftershafts occur in carinate birds, the most common form being one with a very short shaft and long, spreading barbs, very similar in form to plumules. In many gallinaceous birds, e. g., in the Tetraonidae, the aftershaft reaches a very high degree of development, its shaft being frequently three- fourths of the leneth of the main shaft, with its vanes coherent and of even width throughout (fig. A). The usual type in passerine birds, on the other hand, is very different; the shaft is extremely short, with a few short rudimentary barbs near the base, followed by four to eight very long, free barbs, entirely disconnected from each other. The barbs and barbules of aftershafts are always of downy structure, the minute characteristics of the barbules being usually the same as those of the down of the main feather plate, but there are a number of exceptions to this, e. g., in the gallinaceous and passerine birds. In such cases the structure is less specialized 270 Unwersity of California Publications in Zoology Vor. 18 than that of the down of the feather proper, and differs in not possessing certain specialized characteristics, such as the detachable rings at the nodes found in the more basal barbules of gallinaceous birds (pl. 36, fig. 108), and the fimbriae which characterize the base of the inner barbules in passerine birds (pl. 37, figs. 114 and 115). b) Down.—In all but especially modified contour feathers, a vary- ing proportion of the feather plate is downy, the transition from the downy to the pennaceous portion being sometimes gradual, but more frequently abrupt, as shown in text—figure A, the line of demarcation varying a great deal in different feathers. In the lower belly feathers and tail coverts of some birds, e. g., Leptoptilus, the downy struc- ture pervades the entire feather, producing the ‘‘semiplumes’’ of Nitzsch (1867) and others. In Leptoptilus these are the feathers from which the true ‘‘ very similar to these are developed in the lower belly region of turkeys, these being employed very extensively as a substitute for ‘‘marabou’’. The minute structure of the down varies to a large extent in different groups of birds, the nodes and internodes both displaying peculiarities which are highly characteristic of different groups (pls. 34-87). The structure of down often varies a great deal in a single feather, the specific characteristics being always best displayed by barbules on the inner portion of the distal vanule of the basal barbs. Farther distad on either feather or barb, and on the proximal vanules, the structure is often less specialized, and lacks some of the charac- teristic features of the group. This is well displayed in the down of a turkey, where only the inner portion of the distal vanules of barbs on the basal part of the plate possess the peculiar, charac- teristic, detachable rings at the nodes (pl. 36, fig. 108). The strue- ture of the proximal vanules of the same region of the feather often approximates that of the distal vanules, but is never quite so per- fect. The outer barbules of all the barbs, and all the barbules of the more distal barbs, lose the specialization, becoming finally fila- mentous with the nodes very inconspicuous. Though this is the order of reduction of specialization where such reduction takes place, there are some birds in which the downy structure, though highly specialized, is almost uniform, becoming reduced only at the tips of the barbs, as in the Anatidae. As stated above, the structure of the down of aftershafts and plumules, but not of neossoptiles, is 9 marabou’’ of commerce is derived. Feathers 1916] Chandler: Structure of Feathers 271 similar to that of the proximal vanules of the downy barbs of the feather proper, in case there is any special modification in the distal vanules, as in gallinaceous birds. c) Pennaceous Barbules—Concerning the pennaceous portion of contour feathers of the trunk, all degrees of development of structure can be found. In ratite birds, as is well known, there is never any pennaceous structure developed, although the bases of the barbules in Rhea (pl. 13, fig. 1a) are exceptionally well developed for down, and seem to indicate a transition to or from a pennaceous type of barbule. In typical trunk feathers there is no differentiation of inner and outer vanes, and usually the structure is a mere simplifica- tion of that found in the more highly specialized remiges. In the contour feathers of the trunk, as would be expected, the distal bar- bules are of the type of the outer vane of the remiges, and the proxi- mal barbules of the type of the inner vane of the remiges, often in very degenerate form, these types being the ones showing the lesser degree of specialization. In the trunk feathers the conspicuous basal dorsal cilia are seldom developed on distal barbules, and ventral cilia seldom occur on the proximal barbules (pl. 20, figs. 20e and f). Ina great many birds these structures in trunk feathers are very much simpler than they are in the remiges, all of the barbicels being very much reduced or even absent. In distal barbules the cilia often disappear entirely, the hooklets are reduced to one or two very weak ones, and the ventral teeth are represented only by a very small, inconspicuous projection (pl. 33, fig. 92e); the proximal barbules frequently lose the sharp differentiation between base and pennulum, becoming evenly tapering all the way to the tip (pl. 33, fig. 92f). Such modifications are always farther advanced on the breast and belly feathers than on those of the back, the back feathers often being intermediate between the remiges and coverts on the one hand, and the breast and belly feathers on the other. In some birds the pennaceous barbules of trunk feathers have special modifications of their own, and, as might be expected, these are usually more conspicuous and better developed on breast than on back feathers. The most peculiar structural modification charaec- teristic of trunk feathers only, and the only one which needs special mention here, is the development of curved dorsal barbicels on the base of both distal and proximal barbules (pl. 17, fig. 10e, 12a, b). Since these barbicels are not homologous with any other types of 272 Unwersity of California Publications in Zoology (Vor. 18 barbicels, and are always of the same curved form, they have been given a special name, flexules. Though totally absent in the majority of birds they are very characteristic of several groups, namely, Procellariiformes, Grui- formes, and Laro-limicolae (pls. 17, 26 and 28). They are usually not present on some of the basal barbules, but are generally charac- teristic of a considerable portion of the distal vanule, and usually a little less of the proximal vanule. In distal barbules they first develop at the proximal end of the base (pl. 16, fig. 8¢) and progress toward the pennulum, ultimately forming a continuous series with a similar series of pennular dorsal barbicels. This, however, does not happen until the hooklets are lost, since hooklet cells never possess dorsal barbicels of any sort. The result of this is often a conspicuous break in the dorsal series of barbicels on the barbules which still retain the hooklets (pl. 26, figs. 52d, e, and f). In proximal bar- bules the flexules develop first at the distal end of the base as a direct continuation of the pennular series (pl. 16, fig. 52g, h). 4. Ornamental Plumes Frequently some of the contour feathers of the trunk are espe- cially modified as ornamental plumes, the variety of form displayed by them being very great. There is hardly any group of contour feathers which may not at one time or another, in different groups, become modified as ornamental plumes. Among such feathers may be mentioned the diverse kinds of crests developed in many birds, the ‘‘aigrettes’’ of various species of herons, the ruffs and tail plumes of pheasants, the gorgeous upper tail coverts of peacocks and tro- gons, and the very great number of feather modifications in the various species of birds of paradise. Nearly all of these modified plumes are produced either by a mere elongation of the feathers concerned, by an even decomposition of the vanes, or, as in the crest of Gowra and the upper tail coverts of peacocks, by an uneven decomposition, resulting in the production of ocelli, rackets, ete. Although in such decomposed vanes as are found in the ‘‘aiorettes’’ of herons, in the crest feathers of Gowra, or in the com- mercial ‘‘paradise-plumes’’ (chiefly the under wing coverts of Para- disea apoda), the barbs are widely separated from each other on the shaft, and appear macroscopically to be devoid of barbules, closer examination shows that a more or less complete series of degenerate barbules are present, closely appressed to the shaft. In very few A PI q 1916] Chandler: Structure of Feathers 273 cases are the barbules lost, except in connection with color pro- duction, or in case of the tips of the barbs being transformed into stiff spines as in the tails of woodpeckers. A farther modification found in contour feathers is the formation of a terminal undivided horny expansion, produced either by the shaft alone, as in certain rail feathers (Bonhote, 1912), by the coalescence of the shaft and both vanes, as in the crown feathers of the curly-headed toucan (Pteroglossus beauharnaist), or by the fusion of the shaft with the terminal portion of only the outer vane, as in the of Bombycilla garrula (pl. 33, fig. 95a). wax tips”’ 5. Har Coverts On the head of most birds there are a number of modifications of contour feathers to serve special functions, and they are won- derfully adapted to serve their particular purpose. First among these may be mentioned the ear coverts. The typi- cal structure of these feathers is similar to that described by me (1914) in Circus hudsonius. They are loose-vaned feathers, with the barbs wide apart on the shaft, and the short, awl-shaped, degen- erate pennaceous barbules closely appressed to the barbs, thus pro- ducing a mechanism admirably fitted to catch dust particles and yet not obstruct sound. In birds which have well-developed after- shafts this structure is also present in the ear coverts, but in much modified form. In the Limicolae, herons, hawks, and some others, the aftershaft is greatly developed and almost equals the main feather in both size and structure. In Tetraonidae the aftershaft is reduced to a very small downy pad, scarcely larger than a pin- head, which takes no part in covering the ear. An intermediate condition occurs in Grus, where the basal portion of the aftershaft is densely downy, while a few of the barbs are elongated, with the typical appressed, inconspicuous barbules. In owls and many other coraciform and many passerine birds, the ear coverts lack an after- shaft entirely. As has previously been pointed out (Chandler, 1914), the ear coverts are undoubtedly adaptive modifications of contour feathers, which are in a transitional stage of transformation ulti- mately leading to the various kinds of facial bristles and eyelashes. 6. Facial Bristles and Eyelashes The steps in transformation from ordinary contour feathers of the trunk to the highly modified eyelashes of certain birds may 274 Unversity of California Publications in Zoology |Vor. 18 be traced without a break in such a bird as Circus hudsonius, as has been done by me (1914). As was shown there, after the diminu- tion in number of barbs and reduction of barbules, as is the con- dition in ear coverts, the next step is the complete loss of the terminal barbs and elongation of the shaft into a bristle. Then follows the loss of more and more barbs and stiffening of the shaft, until the latter becomes a stout, unbranched bristle, as in the eyelashes of many birds. Usually rictal, supraorbital, and nasal bristles have some of the barbs still present; in the dense nasal tuft of Corvus the structure is very much like that of ear coverts, except that the barbs are set at a more acute angle with the shaft, thus producing narrower vanes. Comparatively few birds possess eyelashes, but when present they are so modified that in some cases nothing re- mains but the stout, deeply pigmented quill, totally devoid of any barbs or barbules. Such is the ease in hornbills, Geococcyx, and some other birds. In birds with aftershafts, although the main shaft is entirely bare, the former is represented by a few small, weak barbs with rudimentary barbules, e. g., Circus, Cathartes, and some others. 7. Facial Ruffs In a few birds, e. g., owls and Circus, facial ruffs are developed, composed of several rows of closely grouped, very compact, curved feathers. The shafts are stiff and inserted almost at right angles to the surface of the body, only the tips beg curved so as to lie flat on the contour. The solid compact vanes are made so by the close approximation of the barbs to each other, and by the exceedingly numerous barbules which have well-formed and characteristic bar- bicels, but are short, due to the shortness of the individual cells, an obvious correlation with the close approximation of the barbs. IV. Cotor Propuction 1. Isotely in Production of Colors The colors of feathers have been studied by a great many workers, chief among whom may be mentioned Altum (1854a, 1854b), Bogdanow (1856), Fatio (1886), Church (1893), Krukenberg (1882), Gadow (1882), and Strong (1902). As shown by the researches of these men and others, the colors of feathers fall into three cate- 1916] Chandler: Structure of Feathers 275 gories, namely, pigment colors, structural colors, and compounded colors, produced by combinations of pigment and structure in differ- ent parts of the same barb. It is not the purpose of the present chapter to deal with pig- ments or methods of actual color production, except in so far as the morphology of the feather parts is concerned, but to show what different modifications occur in feathers of different groups of birds to produce the same results, 1. e., wotely, to use a word coined by Gadow (1911) to mean the attainment of a similar end by different processes in different organisms. Colors which are produced by a single pigment, evenly distributed in the rami and barbules, with no objective color effects, seldom in- volve any modification in the morphology of the barbs. For example, in feathers which have light and dark bars in which the colors are of purely pigment origin, there is no appreciable difference in the form of the barbs in the light and dark areas. The only colors which are produced merely by an even distribution of pigment are blacks, browns, including rufous, and lemon yellow. Although red occurs very frequently as a pigment, it is almost always accom- panied by some structural modification. In the Musophagidae there occurs a green pigment, turacoverdin, which is not accompanied by any special structural modification. Grays, tinged with bluish, rang- ing from pale pearl gray to deep slate gray, are usually produced by an uneven distribution of black or dark brown pigment. In eulls and columbid birds, for instance, the characteristic gray colors are preduced by conspicuous transverse bars of dark pigment on a transparent background in the barbules (pl. 29, figs. 70c, d). In herons nearly the same effect is obtained by a dilute, even pigmenta- tion in the bases of the barbules, supplemented by elongated unpig- mented pennula (pl. 20, fig. 20e). The same method is employed to produce the hoary color of terns and other birds, except that in this case the effect of the unpigmented pennula is accentuated by the long, brush-like ventral cilia. A pretty olive-green color is produced in the back feathers of Osmotreron vernans by a combination of slate and lemon yellow, the former being the effect of dark pigment bars in the transparent bases of the barbules, the latter produced by a lemon- yellow pigment in the pennula, which have large blunt ventral cilia (pl. 29, fig. 69a). Structural colors, i. e., colors which are produced by modifica- tions of structures causing interference or diffraction of light, may 276 Unwersity of California Publications in Zoology Vou. 18 be produced by the rami alone, or by the barbules alone. Although the physical principles upon which the color production rests are probably very much the same in all cases, the mechanisms or surfaces for producing it vary to an astonishing extent in different kinds of birds; the same color is by no means always produced in the same way. As a rule, white is produced merely by the absence of pigment, the barbules being translucent, or semi-transparent, and producing a white color by the diffusion of light by means of the numerous edges and irregularities of surface of the vanules. In some cases, however, more complicated mechanisms are resorted to. In Lagopus the barbules from a white feather appear a peculiar fawn-gray color under the microscope by transmitted light, due to the presence of an infinite number of exceedingly small air bubbles in the substance of the barbules (pl. 24, fig. 47a). When the latter are broken, (i. e., the horny outer sheath rendered penetrable) and immersed in balsam, the latter substance, which has almost exactly the same refractive index as the substance of the feather, destroys the effect of these bubbles by filling in the air spaces, and it is rendered transparent. In many feathers which have conspicuously white shafts or barbs, all or a portion of the barb is filled with a mass of these minute bubbles, appearing under the microscope dark and opaque by trans- mitted light, but glistening white, like a minature snow bank, by reflected light. Such a phenomenon may be seen on the lower side of the rami of belly feathers of Asnydesmus. The silvery straw color found on the outer vanes of the sec- ondaries, wing coverts, and scapulars of Plotus anhinga is produced in an absolutely unique way. The proximal barbules and bases of the distal barbules are black, while the tips of the distals are highly modified, inflated, and without pigment, though seattering the light in the same manner as the rami of Asyndesmus (pl. 18, figs. 13c, e). Like the white rami of the latter, they are rendered transparent when pervaded by balsam. Yellow is sometimes produced by pigment alone, especially in such yellows as those of orioles and wood-warblers, and is then usu- ally produced by pigment in both rami and barbules. Many yellow feathers, e. g@., the straw yellow of the head and neck of Paradisea apoda, possess little if any pigment, and have their color produced by naked rami with longitudinal grooves, or irregular pits. When crushed they are rendered transparent and colorless, and show no 1916] Chandler: Structure of Feathers 277 color by reflected hght. More frequently, as in the belly of Myiarchus and Tyrannus verticalis, the color is a combination of yellow pig- ment and the same superstructure as described above. Orange and red, like yellow, may be produced by pigment alone, by a combination of red pigment and a structural modification, or by a structural modification with an underlying dark pigment. The simplest red is that produced by a diffuse red pigment in both rami and barbules, with no structural modification, as in Cardinalis cardi- nalis. A much deeper and more striking red is produced by a mere glazing or highly polished surface of barbules or naked barbs filled with red pigment, as in the deep red of Nectarinia famosa, or the ‘“wax tips’’ of the waxwing. It is a common phenomenon for red feathers to be characterized by comparatively widely separated trans- verse ridges of one sort or another on the barbs or barbules. In Eudocimus ruber, Phoenicopterus ruber, and some other species, the barbules are inflated, possess a rather dilute red pigment, and have the margins of the cells conspicuously enlarged as ridges (pl. 20, fig. 26a). In the fiery red crest of Tyrannus verticalis the red pigmented barbs have similar transverse striations, produced by rudimentary scale-like barbules, arrested in their development, and fused with the ramus. In hummingbirds only, so far as I have observed, is red pro- duced by iridescence. In the red gorget feathers of many species of hummingbirds, the color is produced by the greatly developed flange, which is broader than the rest of the base of the barbule. and has no apparent striations (pl. 32, fig. 88d). The underlying color is a very dark olive, quite different from the fuscous brown underlying iridescent green or the rufous brown of iridescent blue, a phenome- non which may be explained by the principle of selective trans- mission and reflection. Green is produced in a very large variety of ways. In the Musophagidae alone there is a green pigment, turacoverdin ; in Osmo- treron and a few other birds, some of the feathers appear green from a combination of greenish yellow in the pennula, with some gray or blue color in the bases (pl. 29, fig. 69a). In Melopsittacus a delicate blue-green results from a blue refraction color in the rami, coupled with a greenish-yellow pigment in the barbules. In the vast majority of cases green is an iridescent color, and is the com- monest iridescent color found in birds. The variety of refrangent surfaces is astonishing. In the speculum feathers of ducks, for instance, the cells of the pennula are highly modified into flat, warped 278 Unwwersity of California Publications in Zoology \Vou. 13 structures with a very dark pigment (pl. 21, fig. 287) ; in the green feathers of pheasants and roosters the pennula are modified into spoon-shaped, flat structures with deep pigmentation, with no warp- ing of the individual cells, or constrictions between them (pl. 24, fig. 429g) ; in the peacock, green is produced by barbules which are conspicuously ringed or cross-ridged in both base and pennulum; in hummingbirds by the greatly developed flange of the bases of the barbules (pl. 32, fig. 88d); in trogons by smooth, curved bar- bules (pl. 31, fig. 8la), more or less triangular in cross-section, devoid of barbicels of any kind, and entirely given over to the production of color, the effect of tinsel being consequent upon the broken surface, resulting from the irregular curving of the bar- bules; in Nectarinia famosa by short, flattened barbules, with no barbicels whatever, the entire barbule very closely resembling the pennulum of a green duck feather; and in parrots, coraciids, ete., by the rami alone, in which the greatly developed dorsal ridge is refrangent, the tone of the color varying with the amount of black or brown pigment in the non-refractive barbules. Bronze is produced in manners very similar to those of refraction greens. Blue, except the slate blue of Gouwra, or bluish-gray as of herons and pigeons, is always a refraction color, produced in nearly all the same ways as 1s green, but always underlaid by a warmer brown pigment in accordance with the principle of selective reflection. The pretty light blue of Coracias affinis and some other species is pro- duced by a deep violet refraction color in the hexagonal cells of the ramus, each hexagon, or sometimes only scattered ones, being overlaid by a whitish film which is destroyed by scraping or by crushing which is insufficient to destroy the deeper refraction color. In the case of the hight blue, the barbules are transparent. Various delicate and unusual colors are produced by a combina- tion of structural color in the ramus with a pigment color in the barbules, e. ¢., in Melopsittacus, already cited, and in the blossom- headed parakeet, Palaeornis cyanocephalus, in which the delicate changeable color, ‘‘resembling the bloom of a peach’’, is the result of a combination of a blue refraction color in the rami, and a red pigment in the barbules. It is apparent from this that a great many different methods have been employed in nature in the acquisition of similar results, totally independent of each other, as much so as are the various types of wings produced in insects, reptiles, birds and mammals. 1916] Chandler: Structure of Feathers 279 I can think of no more striking example of isotely, the attainment of the same end by different methods in different groups, than these manifold methods of producing a single color. 2. Effect of Albinism on Structural Color Modvfications One of the most remarkable things about the morphology of feathers is the profound change of structure so frequently involved in the production of color effect, in spite of the surprising con- staney of group characters where no such color modifications occur. It was with extreme interest that the writer examined some of the feathers of an albino mallard, Anas platyrhynchos, to see whether the morphologic modifications involved in the production of the violet speculum would be lost or retained with the lack of pig- ment. It was found that the distal barbules of the outer vane, which in a normal mallard have the pennula highly modified for the production of color (pl. 21, fig. 28a), lacked this modification entirely, and were exactly similar to the normal distal barbules of the outer vane of feathers of this species in which there was no modification for color (pl. 21, fig. 28e). In other words, the con- stitutional factor causing the morphologic specialization of feather structures for the production of color is inseparably bound together with the factor for the accompanying pigment, and if the latter is absent, the feather structures present the normal type of the species in which there are no color modifications. 280 University of California Publications in Zoology Vor. 18 Part II SYSTEMATIC INTRODUCTION After making a careful study of the modifications of plumage of a single individual bird of a representative species, namely, Circus hudsonius (Chandler, 1914), and after making a general survey of the entire class of birds to find out in how far the phenomena there found are applicable to birds in general, a systematic study was made of each order of birds in succession to find out what, if any, modifications of feather structure were characteristic of, or peculiar to, the order or other group in question, and to determine the ex- tent of variation to be found in the group, and to work out, if possible, the probable phylogenetic relationships on the basis of feather structure. 1. Intraspecific and Phylogenetic Modifications At the outset it was necessary to determine how much individual, seasonal, or sexual modification in structure might exist within a species. Examination of a series of birds, in any group in which this has been attempted, shows conclusively that the corresponding feathers of any individuals of a species normally show no appreci- able variation from each other, providing the age, sex, season, and other conditions of the specimens be comparable. In other words, comparable specimens of a species possess a definite, typical feather structure which is normally invariable, as much so as are the muscles, bones, or any other system of the body. Abnormalities and wear may produce considerable changes, but they need not be considered at length here. Fault bars in feathers, for instance, resulting from inadequate nutrition or some other unfavorable condition, produce areas of imperfectly formed barbs; albinism, as shown on page 279, makes a feather which normally possesses a modification in strue- ture for the production of color revert to the normal species type; wear and soiling often give the minute structure a very different appearance; and it is possible that other foreign influences may considerably alter the form and structure of feathers, but these all 1916] Chandler: Structure of Feathers 281 come under the head of pathogenic conditions, and need no further consideration here. Age, seasonal, and sexual variations in feathers occur only when needed for the production of a special result. Just as the greater coverts of a bird may differ in microscopic structure from the middle coverts in order to produce a different macroscopic effect, so in some birds certain of the feathers in the spring plumage may differ from the corresponding ones in the fall plumage, in order to bring about a different total effect. Sexual differences in minute feather strue- ture may likewise exist, but only to produce a macroscopic appear- ance which is a secondary sexual character, e. @., elongated plumes, crests, color effect, ete. Differences in microscopic feather structure are not, in themselves, secondary sexual characters, but are merely employed in the production of more obvious secondary characters. In a few eases variations in feather structure are employed to pro- duce different effects in different ages, even though in the same seasonal dress, as for instance in many of the orioles, whose plumage pattern in the spring of the second year differs from that of the third year. Such changes are rare and occur only in the first few years; when the ultimate adult plumage.is attained, no further age variations occur. As a rule, there are no considerable variations in the feather structure of different species of the same genus, except, as in the ease of intraspecific variations, when instrumental in the production of some larger specific difference. Species, of course, are by no means of equal rank, and in subspecies or in slightly differentiated species feather structure, per se, cannot be used as a taxonomic char- acter, although very slight differences in similar feathers do some- times exist in widely different species of a single genus. Moreover, generic differences in feather structure may usually be passed over, since they are ordinarily so slight that they cannot positively be distinguished at all, or only with intensive study, and then only in case it is certain that the portion examined comes from an exactly similar part of a corresponding feather. In all groups higher than genera, however, epiphyologic differ- ences may almost always be detected. In other words, it is usually possible to distinguish, by details of feather structure, any feather of a specimen of a given family from any approximately similar feather of a specimen of another family, even if in the same sub- order. The amount of differentiation, however, is extremely vari- 282 University of California Publications in Zoology (Vor. 13 able, in some cases being scarcely noticeable, while in others it is very apparent. In the Steganopodes, for instance, the difference in feather morphology in some of the different families is very great, while in the families of Passeriformes, which, as a matter of fact, are hardly more than supergenera, it is extremely difficult to dis- tinguish between even widely separated ones. This difference in degree of differentiation also holds true for groups of higher rank. As intimated above, to be comparable the feathers whose parts are to be compared must be approximately similar, since there is fre- quently more variation between different kinds of feathers on a single body than between corresponding feathers of birds of different orders. For example, the barbules of a remex of Larus differ in their minute structure from those of a breast feather of the same genus far more than they differ from those of a remex of a loon, for instance. 2. Classification Adopted The problem of what recognized system of classification to follow in the study of comparative feather morphology presents itself at this point. To the mind of the writer the system which represents most clearly the true relationships of birds according to the present status of our knowledge concerning them, and one that is coming into very general favor with ornithologists in this country as well as in Europe, is that presented by Knowlton and Ridgway in the Birds of the World (1909). This classification, as stated by Knowlton, is essentially the same as that used by Gadow (1891), modified in some details by the later researches of ornithological workers. Although this classification was adopted in the present study as a mere working basis, it was found that as far as feather morphology was concerned it is apparently a more natural grouping than any other; yet, as will be shown in the following pages, there are some possible changes in it suggested by feather structure, and a hypothetical revision of it, based primarily on the latter, will be suggested at the close of this paper. In the systematie discussion of the various groups, the grouping and suecession used by ‘Knowlton has been used with only two ex- ceptions. The Struthioniformes, Rheiformes, Casuariiformes and Apterygiformes have been included under a common heading Ratitae, as has usually been done, while the Crypturiformes have been dis- sociated from these and placed immediately after the Galliformes, 1916] Chandler: Structure of Feathers 283 where, according to their epiphyology, they seem to belong. The classification as here used is as follows: CLASS AVES Subclass Neornithes I. Ratitae Order Struthioniformes Rheiformes Casuariiformes Apterygiformes II. Carinatae Order Sphenisciformes Colymbiformes Procellariiformes Ciconiiformes Suborder Steganopodes Ardeae Ciconiae Phoenicopteri Order Anseriformes Suborder Anseres Palamedeae Order Falconiformes Suborder Cathartae Gypogerani Accipitres Order Galliformes Suborder Galli Turnices Order Crypturiformes Gruiformes Charadriiformes Suborder Laro-limicolae Pteroclo-columbae Order Cuculiformes Coraciiformes Suborder Coraciae Striges Caprimulgi Cypseli Colii Trogones Pici Order Passeriformes 3. Methods of Comparative Study In working over the morphology of feathers in each of the above eroups, a brief survey of feather structure was made of a series 284 University of California Publications in Zoology [Vor.18 of representative species, representing both the typical and out- lying forms included, and then a species which seemed to be fairly typical for the entire group was selected for careful study, and the minute structure of its remiges and body feathers worked out in detail. So far as possible, except in the Passeriformes, repre- sentatives, usually several, of each included family were examined to determine the constancy of the characters found in the selected type, and where important differences were found in other groups of the same order or suborder, their epiphyology was also worked out in detail. Since it was obviously not possible to examine more than a few feathers of each bird studied, similar feathers, as far as possible, were studied in each group taken up, namely, both inner and outer vane of a typical remex (i. e., not a highly specialized outer pri- mary or a weakened inner secondary), a back feather, and a breast feather, though in many eases the latter two were so similar that they did not merit separate descriptions. In other words, the method of study of groups has been: (1) a detailed study of represen- tative feathers of a type, and (2) a study of a number of other selected species, to determine the constancy or modifiability of the characters observed in the type, and to discover the presence or absence of further or different modifications. A discussion of the relationships suggested by feather morphology, and a review and summary of the epiphyology is given at the end of the section deal- ing with each group especially treated. I. Ratrrar Although there has been some doubt concerning the natural asso- ciation of all the so-called ratite birds into a single group, as far as feather structure is concerned, this grouping seems to be en- tirely permissible, providing the Crypturiformes, which Knowlton placed with them, be removed. The following characters are com- mon to the entire group, and as far as we know are not present, except as noted, in the adults of any other birds: (1) plumage uni- form, not segregated into pterylae (found only in Sphenisciformes and Palamedeae among carinate birds) ; (2) total absence of differ- entiated plumules and filoplumes; as far as known, both these types of feathers are never missing simultaneously in other birds; (3) en- tire absence of true pennaceous structure in any of the feathers, 1916] Chandler: Structure of Feathers 285 the barbules in some species being more or less intermediate be- tween a downy and a pennaceous type. 1. Order STRUTHIONIFORMES Pl. 13, Fig. 2 This group, which includes only the ostriches, of which four closely related species have been described, has a great many peculiar epiphyological characters, most of which, it seems to me, may be considered primitive, rather than secondarily acquired degenerate conditions. They may be enumerated as follows: (1) in common with other Ratitae, an even distribution of feathers, the only apterium being the central one on the breast, where there is a callosity developed by the bird’s habit of resting on its breast, and the total absence of plumules and filoplumes; (2) the great increase in the number of rectrices and remiges, the latter to 36 or more, considered by Beebe (1904) to be a secondary specialization, though by some considered a primitive character; (3) the projec- tion of the remiges beyond the bone instead of fitting into grooves in it as in all earinate birds; (4) the wide angle of insertion of the phalangeal primaries, which in other birds are attached almost parallel to the long axis of the phalanges; (5) the absence of all but one row of under wing coverts; (6) the total absence of after- shafts; (7) the total absence of a typical pennaceous structure in the feathers. a) Struthio camelus (1) Remiges The feathers of ostriches, as already stated, are all of one type, and not differentiated into contour feathers, plumules, and_filo- plumes. The aftershaft is entirely lacking. The rectrices and remiges are developed into very large, curling plumes with loose, drooping vanes, but in their minute structure differ in no essential way from any of the body feathers. Shafts relatively stout, usually widely and more or Jess deeply grooved’ beneath. In male wing plumes, for instance, the groove so deep and prominent as to make the shaft C-shaped in eross- section and shell-like almost to tip. Width of the shaft of a small wing plume, 6 to 7 mm. at the base, tapering gradually all the way to the end; its depth about 4 mm., 3 mm. of which is involved in the groove. Barbs, which may reach a length of 15 or 20 em., usually set 286 University of California Publications in Zoology (Vou. 18 about 8 per centimeter on each side throughout most of the feather, increasing to about 12 or 14 at the base. Rami not lamel- late as in most carinate birds, but more closely resembling the rami of down; no prominent dorsal or ventral ridges. Inner and outer vanes undifferentiated. Barbules (pl. 13, fig. 2a) differing widely in form from those of any other birds, either ratite or carinate, at once recognizable. Not differentiated either into distal and proximal, or outer vane and innner vane types, nor any considerable difference in structure and form, except length, in different parts of feathers, or in feathers of different parts of the body. Barbules not clearly differentiated into base and pennulum, even to the extent of ordinary down barbules, and further differing from the latter in being flat and ribbonlike instead of filamentous, in this particular approaching pennaceous barbules but differmg from them in being bilaterally symmetrical. On best developed barbules, no prongs or barbicels whatever, but small rudimentary prongs, as in barbules of body feathers, on weaker ones at base and tip of barbs. Length of bar- bules from 2.5 to 3.5 mm.; width, about 0.035 mm., this being comparable with that of pennaceous barbules; on an average about 25 to 30 barbules per millimeter on each vanule, thus more widely spaced than usual with ordinary down barbules. (2) Other Feathers of Adult The feathers of back, rump, belly, ete., not differing in any considerable degree from remiges. Barbs set closer, about 12 to 18 per centimeter throughout length of feather, usually under 5 em. long, basal and distal ones usually shorter resulting in doubly tapering form of feathers. Barbules of approximately same form as in remiges (pl. 13, fig. 2b, 2c), those of the less well-developed feathers with rudimentary prongs at the junction of the cells, called “‘vestigial barbicels’’ by Beebe (1904). Length variable, less than in remiges, usually under 2 mm. Feathers of head and neck small, with elongated, bare, hairlike shafts. Eyelashes present, in form of stiff, coarse bristles, with a few basal barbs. Specialized ear coverts present, similar in general plan to those of carinate birds, the shaft furnished with a series of stiff and elastic bristle-like barbs, entirely separate from each other, arranged like the tufts of a brush rather than in distinct vanes, and barbules very small, rudimentary, and appressed. In all small feathers of head and neek, including eyelashes and ear coverts, elongated, bristle-like shafts naked, but barbs always with complete series of densely set and very short barbules, only 0.015 to 0.03 mm. long, but of typical ribbon-like form. (3) Nestling Feathers The nestling feathers of ostriches have exactly the same type of structure of barbules as teleoptiles, which fact furnishes some evidence that the latter are not degenerated pennaceous barbules but are highly developed downy ones, since down barbules are the only ones ever found in neossoptiles. The barbules of the latter 1916] Chandler: Structure of Feathers 287 (pl. 18, fig. 2c) differ only in their shortness, reaching a length of considerably less than 1 mm., the width and flattened ribbon-like form remaining the same. In the nestling feathers many of the barbs bear barbules only near the base, the terminal portion being extended hairlike or expanded into a more or less curled, flattened plate (pl. 18, fig 2d). Duerden (1911) gives an interesting account of the sequence in the plumages of ostriches. b) Relationships As has been shown, the feather structure of ostriches seems to indicate a primitive rather than a degenerate condition. Their wings, which have no specialized pennaceous remiges, and could have no lifting function, are used for aiding the bird in running against the wind, as suggested by Beebe (1904). This use is highly suggestive of a possible course of evolution of flight. When once the remiges had become pennaceous, nothing further would stand in the way of their being used for true flight. Beebe (1904) looks upon this use of the wings as a half return to the lifting function of the wings in the flying ancestors which he assumes for the eroup, a view which seems to me to involve so complicated a path of evolution as to require very strong positive evidence to support it. ‘ The same author remarks that ‘‘vestiges of barbicels’’ can easily be distinguished. He evidently considered the downy feathers of ostriches as being derived from pennaceous feathers, though nothing in their structure or arrangement, it seems to me, need be inter- preted as suggesting this. The barbules, while less specialized than typical pennaceous barbules and more specialized than simple down barbules, are not intermediate, and might be more easily looked upon as marking the end of a short path of evolution of their own, than as degenerate forms of either of the other types. If the contour feathers of ostriches are not derivatives of pennaceous feathers, then ostriches are not descendants of flight birds, and their striking primitive characters need not be looked upon as secondarily acquired. The absence of plumules, filoplumes, and aftershafts, the even distribution of feathers over the entire body, and the similarity of the neossoptiles to the teleoptiles, as well as the general form of the barbules, all suggest the possibility of the ostriches not being derived from birds with pennaceous feathers, and therefore not from flight birds. 288 University of California Publications in Zoology \Vor. 18 c) Summary The ostriches, in addition to the characters common to all Ratitae, have the following characters: (1) Aftershaft absent. (2) Types of barbules similar on all feathers of both nestling and adult. (3) Barbules of elongate, ribbon-like form, more or less inter- mediate between an ordinary downy and a pennaceous type, but dif- ferent from either, with no differentiation of base and pennulum, and no barbicels except rudimentary prongs in body feathers. (4) Possibility of their not being derived from flight birds strongly suggested by epiphyology. 2. Order RHEIFORMES Pl. 13, Fig. 1 Although grouped as a separate order of the Ratitae, equivalent to any of the other three, the rheas are much more closely related to the ostriches than are either to any others of the Ratitae, espe- cially as regards their epiphyology. Rheas agree with ostriches, in addition to the common ratite characters, in (1) the large number of primaries (12 to 16 in Rhea), (2) the reduction of the under wing coverts, they being totally absent in Rhea, (3) the absence of aftershafts, and (4) the type of barbules, which, as in ostriches, are intermediate between downy and pennaceous barbules. The chief differences between the two groups in general epiphyologie characters are: (1) the absence of well-developed rectrices in Rhea, (2) the more obtuse angle made by the attachment of the phalangeal primaries in Rhea; (3) the approach to the carinate type of the relation of the remiges to the arm bones; and (4) the better development of the feathers of the head and neck. The details of structure of the feathers, as compared with ostriches on the one hand and earinate birds on the other, are exceedingly interesting. a) Rhea americana (1) Remer Shaft, unlike its condition on some ostrich feathers, finely ridged and grooved on ventral side, with no large conspicuous groove in middle. As a rule, the shaft not as short or heavy relative to feather as in ostriches. 1916] Chandler: Structure of Feathers 289 Barbs very similar to those of ostriches, with no perceptible ventral or dorsal ridge, and with barbules attached almost at right angles in an even series almost directly opposite each other, and not at obviously different levels as in pennaceous feathers. Change in number of barbs per unit of measure from base to tip of feathers considerable; about 20 per centimeter at base of feather, dimin- ishing to only 8 or 9 near tip. Inner and outer vanes similar. Barbules considerably advanced over those of ostriches in their greater variability in different feathers and parts of feathers, also in their closer approximation to both a pennaceous and downy type. Set about 35 per millimeter on each side on basal barbs, and only about 20 per millimeter on terminal ones. No differentiation between distal and proximal barbules. The best developed barbules on basal portion of barbs on terminal halves or remiges (pl. 13, fig. la). Length about 2 mm., the basal one- third, more or less, considerably broadened into specialized base, not bilaterally symmetrical, but furnished with a series of ventral prongs or barbicels, the dorsal edge smooth and unbroken. Pen- nulum cylindrical, with more or less well-developed prongs for its entire length. Development of basal portion into a differentiated unsymmetrical base, with distinetly barbicel-like prongs, and of terminal portion into a filamentous pennulum, shows distinct approxi- mation to pennaceous barbules, at least much nearer than the simple, ribbon-like barbules of ostriches. Barbules from middle part of either vane of same feather (pl. 13, fig. lc) considerably less specialized. Basal portion much narrower with less distinct barbicels, and a much less obvious distinction be- tween flattened base and filamentous pennulum. (2) Other Feathers No essential differences from remiges in structure of body feathers, but barbs more numerous. On small rump feather they decrease from 40 per centimeter on each side at base to about 22 at tip, in upper back feather less numerous, 30 per centimeter basally to about 13 at tip. In these cases number of barbs per unit of measure apparently increases inversely to size of feather, or, in other words, space between barbs is directly proportional to size of feather. Barbules less differentiated into base and pennulum than in remiges (pl. 18, fig. 1b), and shorter, with decided tendency toward ordinary downy type, similar to that of penguins, and to neossoptiles of many water-birds. I have had no opportunity to study neossoptiles of rheas, but they are stated by Gadow (1891) to be ‘‘buschelformig’’ as in ostriches, but with a weakly developed shaft. b) Relationships Like the Struthioniformes, the rheas show characters which might be construed as evidence of their being primitive in their flightless condition and of not being descendants of flying birds. 290 Unwersity of California Publications in Zoology \Vou. 18 As shown above, they resemble the ostriches in many details, and are unquestionably more nearly related to them than to any other Ratitae. In the general arrangement of feathers and in the form of the barbules, while probably, like ostriches, at the end of a short separate path of evolution, they appear to be nearer the line of descent of carinate birds. Special attention is drawn to the fact that the barbules which approach most nearly a pennaceous type, are in the positions where pennaceous barbules are most likely to be found at the height of their development in carinate birds, i. e., on the basal portion of barbs beyond the middle of the feather. c) Summary In addition to common ratite characters, Rheiformes are char- acterized by the following in common with ostriches: (1) Absence of aftershafts. (2) No under wing coverts (one row in ostriches). (3) Unusually large number of primaries. (4) A type of barbule which is intermediate between a downy and a pennaceous type, differing, however, from ostriches. They are further characterized by: (1) Differentiation of the barbules of different portions of feathers. (2) Highest developed barbules with flattened base provided with barbicels on ventral edge only, and filamentous pennulum with prongs similar to those of typical down feathers of penguins. (3) Less highly developed barbules with basal portion reduced, thus becoming still more like the down barbules of penguins. 8. Order CASUARIFORMES 1G I ERE By The birds of this group differ very considerably from the ratite birds previously studied, but agree with them in the several important characters common to all ratites. Although Nitzsch (1867) described filoplumes from a cassowary, he was undoubtedly mistaken in his identification of them (see Part I, p. 260), for filoplumes are as com- pletely absent in this group as in any of the other Ratitae. Unlike those of the ostriches and rheas, the primaries are greatly reduced, hardly differentiated at all in Dromaeidae, and reduced to five or six stiff black spines in Casuariidae, representing, according to Beebe 1916] Chandler: Structure of Feathers 291 (1904), only the hypertrophied calami, the scanty-vaned shaft being first formed and then broken off at the superior umbilicus. No special- ized rectrices are to be found. The aftershaft is enormously developed, nearly or quite equalling the main feather plate, a condition found elsewhere only in plumules and in the ear coverts of some birds. The plumage of these birds differs widely from that of the ostriches and rheas in being very hairlike and harsh to the touch, a condition brought about by the looseness of the vanes, and the stiffening of the rami, coincident with a reduction and loss of the barbules. a) Dromaeus novae-hollandiae (1) Body Feathers Body feathers characterized by great slenderness of form. Feather plate extremely long relative to width; total length in a typical back feather of both shaft and aftershaft, about 20 to 25 em.; width approximately uniform for entire length, less than 1.5 cm. wide; feather slightly rounded at tip. Aftershaft not appreciably different. Shaft slender, slightly more so in aftershaft, with a broad, shallow, ventral concavity. Rami typically of rather peculiar form, espe- cially towards tip of feathers, where in many feathers the barbules are more and more restricted to basal portion of barbs and finally lost entirely. These naked terminal barbs set as close together as are the middle, barbuliferous ones (about 8 or 9 per centimeter), with rami very deep dorso-ventrally, and sword- shaped, dorsal edge wide and smooth like the upper edge of a sword blade, lower edge thin and sharp, tapering up to meet the upper edge at tip (pl. 14, fig. 4a). Rami of more proximal barbs, bearing barbules, similar but not so wide or so evidently sword- shaped. Barbules alike on inner and outer vanes, usually present to tips of barbs on at least two-thirds of feather, and sometimes to tip of feather; about 1 to 1.8 mm. long, very slender, and very numer- ous, set about 30 to 35 per millimeter on both sides. Unlike those of ostriches and rheas, barbules of typical downy type, with narrow, flattened base, and long, filamentous pennulum (pl. 14, fig. 4b). Base short, of moderate width, pennulum almost absolutely thread- like, the nodes very inconspicuously marked by minute prongs. All barbules from either aftershaft or main feather plate, and from all feathers examined, similar in form, differing only in size. b) Other types. Casuariudae Though very much like the emus in all the important characters of their epiphyology, cassowaries differ in a few minor details. 33 middle portion of the barbs. The pennula are short, not over half the length of the bases. In no birds which I have examined is there a greater difference between the leneth of the bases of distal and proximal barbules on the same barb. To counterbalance this great difference in size, in order to produce fairly equivalent vanules, the angle of insertion of the distals is unusually wide, while that of the proximals is unusually acute, this in turn result- ing in an astonishing difference in number of barbules per unit of measure. While there are 40 or more distals per millimeter, there are only 16 or 17 proximals for the same distance. On the outer vane the distal barbules differ from those of the inner vane only in the absence of the dorsal cilia, and sometimes in the presence of one more hooklet. The proximals (pl. 19, fig. 17c), except on a small portion of the tip of the barb, are similar to those of the inner vane except that they are short, and rela- tively broader. On the distal part of the barb the ventral teeth increase to about six in number, become separated, and are trans- formed into very long, stout, curved barbicels, resembling the teeth of a large-toothed comb. The pennulum is shortened so that it does not extend more than one cell beyond the barbicels; the base is likewise shortened and reduced. The primaries of Pelecanus californicus are similar to those described above. The secondaries and coverts, however, have the distals transformed to produce the characteristic hoary effect. These barbules (pl. 19, fig. 18a) have their bases reduced in size, the hooklets shortened, and the pennula elongated, with a double series of long, slender cilia. They resemble very closely the distal barbules of the hoary feathers of Phalacocorax (pl. 18, fig. 14e), but the pennula are not so broad, while the cilia are longer and more prominent. In the breast feathers of Pelecanus, at the base of the barbs the barbules have a structure similar to that found in Sula and other Steganopodes, a proximal barbule from this portion being shown in plate 19, figure 17e. The outer portion of the barb, however, develops typical flexules on both distal and proximal barbules, ex- actly as in the Procellariiformes. Plate 19, figure 17d, shows a distal barbule from a breast feather of P. erythrorhynchus and comparison with plate 17, figure 10e (Diomedea exsulans) will show the striking similarity. At the extreme tip both barbules assume the form shown in plate 19, figure 19e (Phaéthon), which 314 University of California Publications in Zoology \Vou.18 should be compared with plate 17, figures 12@ and 12b. Pelecanus californicus has the same type of structure. (5) Phacthontidae The Phaéthontidae or tropic birds, as far as feather structure is concerned, seem to show a perfect transition from the Procel- lariiformes on the one hand to the Laro-limicolae on the other, though apparently more closely related to the latter. As shown by plate 19, figure 19a (Phaéthon rubricauda), the base of the distal barbules of the inner vane is relatively large and broad, and the ventral teeth long and slender, with a very slight tendency to bifureate, not always displayed, however. The hooklets are only four in number, and relatively short and small, the ventral cilia are much reduced, and the dorsal ones likewise, except the basal two, which are strongly reminiscent of Laro-limicolae. The prox- imal barbules (pl. 19, fig. 19b) differ from those of other Stegano- podes, but agree with the Laro-limicolae in their relatively small size, and in having small inconspicuous ventral teeth. There is another significant difference in the relative number of distal and proximal barbules. In all other Steganopodes there are nearly twice as many distals as proximals, while in Phaéthon there are 22 or 23 proximals to 30 distals, this genus thus resembling both the Procellariiformes and the Laro-limicolae. The barbules of the outer vane, the forms of which are shown in plate 19, figures 19c and 19d, are characterized primarily by their slender form, the wide separation of the hooklets of the distal barbules, which are all of nearly equal length, and the weak ventral cilia of the prox- imal barbules. The rami of the outer vane have the ventral edge serrate and broken into villi, a condition which reaches the height of its development in the Anseres. The barbules in back feathers of Phaéthon rubricauda closely resemble those of the inner vane of the remiges, except in their smaller size. The breast feathers, as in Pelecanus among Steganopodes, and like the Procellariiformes and Laro-limicolae, develop flexules, but not aS numerous or as well-formed ones as in Pelecanus. Plate 19, figure 19e, shows a proximal barbule from the terminal por- tion of a barb from a breast feather, while figure 19f of the same plate shows a distal barbule from a portion not quite so near the tip. Its base is much reduced, and it has weak barbicels; a little more distally it assumes a form similar to that represented in plate 1916] Chandler: Structure of Feathers 315 19, figure 19e. Unfortunately these two figures were reversed in position from the system usually followed in the preparation of the plates. c) Down The down of Steganopodes, like the pennaceous structure, is extremely variable. In Phalacocorax, Fregata, Pelecanus and Phaé- thon the downy barbules are of moderate length, i. e., from 1.0 to 1.3 mm., and smoothly filamentous except in Pelecanws, which has minute prongs at the nodes on the distal portion of the barbules. In Plotus the downy barbules (pl. 34, fig. 99) are also filamentous, but are very long, frequently reaching a length of over 2 mm. Sula differs not only from other Steganopodes but also from all other birds in the enormous development of the prongs at the nodes. These reach a length of over 0.1 mm. in barbules which are only 0.6 to 0.8 mm. long, being slender, filamentous, and frequently bifurcated (pl. 34, fig. 98). The only other birds which begin to approach Sula in the length of the prongs are albatrosses and puffins, and this might be looked upon as additional evidence of fairly close relationship between the Sulidae and the Procellariiformes. ad) Relationships The Steganopodes are a group of birds in which primitive char- acters are curiously combined with specialized characters, the result being a rather heterogeneous aggregation of more or less related forms which are specialized along different lines. They seem to fall into three fairly well-defined groups as follows: (1) Phalaco- corax, Fregata, Sula and Pelecanus; (2) Plotus; and (3) Phaé- thon. The first group may be regarded as containing the most typical Steganopodes, since they form the bulk of the group, and are least specialized. They seem undoubtedly to be derived from a primitive procellariiform type, and as certainly to stand at the base of the ciconiiform group, the next above them being the Ciconiae. The second group, including only the neotropical genus Plotus, though often grouped only as a sub-family of the Phalacocoracidae, differs very widely from the other Steganopodes in the structure of its feathers, in which it is very specialized. In some details of the feather morphology this genus shows such striking similarity 316 University of California Publications in Zoology Vor. 138 to the Cathartae that their kinship can hardly be doubted. This will be forcibly shown by a comparison of plate 18, figures 13a and 13b, with plate 22, figures 34 a@ and c. This close similarity of the Cathartae with Plotus, accompanied as it is by other common char- acters as shown by Gadow (1891), suggests the possibility of re- earding the Cathartae as direct descendants of the Steganopodes, from a form not far removed from Plotus. The third group, Phaéthontidae, is so strikingly like the Laridae that their affiliation with the Steganopodes seems very doubtful, and if feather morphology be considered, they should be looked upon rather as aberrant larid forms. Comparison of plate 19, figures 19 a-f, with plate 28, figures 61 ae, will make clear the marked similarity in feather morphology. e) Summary The Steganopodes are divisible into three groups on the basis of feather morphology, the typical Steganopodes, Plotus, and Phaéthon. The first group is characterized as follows: (1) Plumules uniformly distributed ; (2) Aftershaft absent or rudimentary ; (3) Distal barbules of remiges relatively small as compared with proximals, and much more numerous, the difference in num- bers much greater than usual; (4) Distal barbules of remiges with short, broad base, with broad lobate ventral teeth, except in Sula, where they are relatively small and narrow; pennulum moderate in length, hooklets slender and progressively longer, ventral cilia long and slender, basal dorsal cilia, on inner vane, stout and triangular, gradually changing to a spiny, and ultimately a filamentous form; (5) Proximal barbules of remiges with base long and large rela- tive to distals; ventral teeth long and conspicuous on inner vane, transformed into a weak series of ventral cilia on outer vane; pennulum rather broad, usually shorter than base, but sometimes as long. (6) Back feathers with bases of both distal and proximal barbules elongate, the distals with long pennula, with double series of well- developed slender cilia, except where specially modified for produc- tion of iridescent color; hooklets short; proximal barbules with tendency to develop weak ventral cilia; 1916] Chandler: Structure of Feathers 317 (7) Breast feathers similar but weaker, without flexules except on outer part of barbs in Pelecanus and Sula; (8) Down barbules of moderate length, smoothly filamentous, or with minute prongs at nodes on their distal portion except in Sula, where prongs at nodes are enormously developed, to an extent approached among other birds only in some Procellariiformes. Plotus, constituting the second group, is characterized as fol- lows: (1) Proximal barbules very small relative to distals, the length of their bases actually less. (2) Distal barbules of inner vane of remiges with ventral teeth lobate, their ventral edge in a continuous line with ventral edge of base; hooklets relatively small and very stout, progressively longer ; ventral cilia coarse, blunt, and rodlike, more or less appressed to pennulum; no dorsal cilia except one, or sometimes two, stout, blunt, spinelike basal ones, followed by a dip in the dorsal contour of the barbule, thus giving it a characteristic shape. (3) Proximals of both vanes of remiges with very short, small base, inconspicuous ventral teeth, and short, conspicuously wide pennulum, with recurved spines. (4) Silvery gray color of parts of outer vane due to a greatly expanded and inflated unpigmented pennulum bearing small, stout hooklets and extremely long, slender, closely associated ventral cilia. (5) Body feathers with distals and proximals both similar to remex type, of which they are mere simplifications; no flexules developed. (6) Down barbules smooth and filamentous, and longer than in any other Steganopodes, frequently over 2 mm. The third group, including only the monogeneric Phaéthontidae, is characterized as follows: (1) Distal barbules of remiges large as compared with proxi- mals, and the latter over two-thirds as numerous. (2) Twist between base and pennulum of distals producing sharp curve in the dorsal contour as barbule lies in normal posi- tion; ventral teeth small and slender; hooklets slender, rather weak, and well separated from each other; ventral cilia reduced; and basal dorsal cilia of inner vane lobate, almost exactly as in gulls. (3) Proximal barbules of remiges with narrow base, short pen- nulum and short inconspicuous ventral teeth on inner vane, a series of weak ventral cilia on outer vane. 318 Unwwersity of California Publications in Zoology ‘Vou. 138 (4) Breast feathers with flexules developed on terminal por- tion of barbs of breast feathers. (5) Down smooth and filamentous, little if any over 1 mm. long. Il. Suborder Crconrar Pl. 20, Figs. 23-27 Constituting the second suborder of the Ciconiiformes are the storks and ibises, which, together with the Ardeae, form a compact and well-defined group. Although the typical Ardeae are readily distinguishable from typical Ciconiae, there are a number of more or less intermediate forms which make their characterization by other characters as well as by epiphyology very difficult. Ex- cluding Balaeniceps and Scopus, which combine characters of both groups, the Ciconiae are distinguished from the Ardeae by the fol- lowing characteristics: (1) absence of powder down, (2) even distribution of plumules in both pterylae and apteria, and (3) feathered lores. The aftershaft is very variable, being present, rudimentary, or absent in different genera. a) Mycterva americana (1) Remex Shaft stout and square, about as deep as wide, with broad, V- shaped ventral groove, and fine striations on sides where barbules are attached. Rami not greatly deepened at junction with shaft but deeper than usual in Steganopodes. Pith cells more than a single layer thick, and ventral edge of rami of both outer and inner vanes without villi. Distal vanule with barbules greatly outnum- bering those of proximal vanule, the barbules about 40 per milli- meter on former, only 18 per millimeter on latter, this difference ac- companied by great difference of angle of insertion of barbules on ramus. Inner vane—Distal barbules (pl. 20, fig. 23a) small relative to proximals; base of moderate size, about 0.35 by 0.05 mm., with fairly large, lobate ventral teeth, frequently blunt and_ slightly incised at tip; pennulum characterized by stout heavy form; hooklets numerous, 6 or 7 in number, moderately stout, and pro- eressively increasing a great deal in length; ventral ciha rather poorly developed, present all the way to tip of pennulum, straight, and appressed to barbule; basal dorsal cilia stout, blunt, and spine- like, well separated from each other, the first one always the largest ; usually three such stout barbicels developed, the following ones becoming more and more like the ventral ones. Proximal barbules (pl. 20, fig. 23b) with very large bases, about 0.7 mm. long by 0.07 mm. wide with a series of broad, triangular ventral teeth projecting very little beyond the ventral contour of barbule; pennulum re- 1916] Chandler: Structure of Feathers 319 markably short, about half length of base, very broad proximally, and tapering rapidly to tip; pigment deeper ventral to nuclei than dorsal to them, reverse being more frequently true in other birds. Outer vane—Distal barbules differ only in absence of dorsal cilia, except a few terminal rudimentary ones (pl. 20, fig. 23¢). Proximals, unlike those of any birds so far studied except peli- cans, differ only slightly from those of inner vane, being somewhat smaller, their form exactly similar except that ventral teeth are slightly longer, with tendency to become hooklike, but even at tip of barbs not increasing in numbers and forming a series of ventral barbicels. (2) Other Feathers Back feathers have same structure as outer vane of remiges except that small dorsal cilia are sometimes developed on distal barbules near the base of more proximal barbs. In breast feathers structure not essentially different. Distals (pl. 20, fig. 23d) more elongate, and dorsal cilia, except at proximal end of pennulum, better developed. Proximal barbules of exactly same type as in remiges, in neither distal nor proximal barbules any tendency what- ever for development of flexules. b) Other Types Ciconia ciconia has a very similar structure of its feathers. The chief difference is in the relative narrowness of the proximal barbules. Leptoptilus dubius has a slight modification of the structure of distal barbules as compared with those of Mycteria. The first two dorsal barbicels of distal barbules of the inner vane (pl. 20, fig. 24a) are stout and spinelike as usual, but are very much closer together and are not followed by a series of less specialized cilia, thus approach- ing more closely to the heron type. On the outer vane the pennulum of distal barbules is relatively short and furnished with an even series of short blunt dorsal cilia (pl. 20, fig. 246). The under tail cov- erts of Leptoptilus deserve special mention as they are the source of the famous ‘‘marabou’’ feathers of commerce. These feathers are furnished with stiff, heavy shafts, but have the entire feather downy in structure, a condition seldom found in contour feathers, except occasionally on a very weakly developed breast or belly feather. In Plegadis guarauna, or scarlet ibis, there is a very striking modification in the distal barbules to deepen the scarlet color-effect (pl. 20, fig. 26a). As will be seen from this figure, both base and pennulum are profoundly transformed, and all the barbicels except the hooklets are lost or greatly changed. Both base and pennulum 320 University of California Publications in Zoology (Vou. 18 are characterized by a series of transverse rings which evidently have a tendency to break up the light and deepen the red color produced by the diffused pigment. The proximal barbules remain practically unchanged. 5 Ajaja ajaja, representing the Plataleidae or spoonbills, resembles Plegadis very closely. Both Plegadis and Ajaja have the ventral edge of the rami serrate. The similarity of the barbules of the back feathers to similar ones of Mycteria is shown by plate 20, figure 27a, as compared with plate 20, figure 23c. c) Down The down barbules of Mycteria americana and of other Ciconiidae are long, frequently over 2.5 mm., and are very slender and filamentous, with minute inconspicuous prongs, or none what- ever, at the nodes. In the Ibididae and Plataleidae, on the other hand, the down barbules are rather short, usually under 1 mm. in length, and very stout and coarse, the internodes with longitudinal ridges and grooves, and the nodes with well-developed prongs. A down barbule of Guara rubra is shown on plate 23, figure 101. ad) Relationships The Ciconiae form the middle section of the Ciconiiformes, the Steganopodes being below them and the Ardeae and Phoenicopteri above. Undoubtedly their closest relatives are the herons, with which they are joined by such intermediate forms as Balaeniceps and Scopus, the feathers of which I have been unable to obtain for study. The Phoenicopteri appear to connect the Ciconiae with the Anseres. No relation whatever is shown by the structure of the feathers to the Limicolae or to typical Gruiformes. e) Summary The Ciconiae are characterized as follows: (1) Barbules much more numerous on distal than on proximal vanule. 2. Distal barbules with base of moderate size relative to prox- imals, with moderate, lobate ventral teeth ; pennulum stout and heavy, with 6 or 7 moderate-sized, progressively longer hooklets; ventral cilia more or less appressed, straight, usually blunt; on the imner vane about three well-separated, stout, basal dorsal cilia, followed by less 1916] Chandler: Structure of Feathers 321 specialized ones, except in Leptoptilus, where there are only 2, and these close together. (3) Proximal barbules with large bases, inconspicuous ventral teeth, a short but broad and tapering pennulum, and no ventral cilia developed on outer vane. (4) Ventral edge of outer rami of primaries serrate in Ibididae and Plataleidae, but smooth in Ciconiidae. (5) Body feathers with barbules as in remiges, but more elongate and slender; never any flexules. (6) Down barbules in Ciconiidae long, slender, and filamentous, with small inconspicuous prongs or none at all; in Ibididae short, stout and heavy, longitudinally ribbed, and with well-developed prongs at the nodes. Ill. Suborder ARrpDEAE Pl. 20, Figs. 20-22 As stated above, the typical Ardeae are readily distinguishable from the Ciconiae, but Balaeniceps and Scopus combine the char- acters of both groups in such a way that the characterization of either is very difficult without allowing for these exceptions. Unfortunately I have not been able to obtain feathers of either of these genera for study, in order to find out whether their feather structure adheres to the typical ardean type or approaches that of the Ciconiae. Having no data concerning either of these two out- lying forms, nor of Cochlearius, the present section deals only with the Ardeidae, including the herons, egrets and bitterns. Their general epiphyological characteristics are as follows: (1) plumules confined to the apteria, (2) powder down present, (3) aftershaft present, and (4) lores naked. a) Ardea herodias (1) Remexr Shaft and rami very similar to those of Ciconiae, the shaft, if anything, slightly deeper than wide, with V-shaped ventral groove, and fine striations on side. Rami not considerably deepened, even on outer vane, the pith not more than a single layer in thickness and the ventral edge not serrate or furnished with villi. Distal vanule with about 30 barbules per millimeter, proximal vanule with about 18 per millimeter. Inner vane.—Distal barbules (pl. 20, fig. 20a) with small base, about 0.26 by 0.04 mm. with relatively very large, leaf-like ventral teeth so shaped and arranged as to form a single, large, blunt, 322 University of California Publications in Zoology Vor. 18 subtriangular lobe; pennulum with very characteristic form, differ- ing considerably from those of Ciconiae, though approached in Leptoptilus; hooklets similar to those of Ciconiae, but normally only 5 in number, followed by 3 or 4 steadily diminishing ventral cilia, beyond which the pennulum is greatly elongated, rather slender, and totally unbarbicelled; 2 basal dorsal cilia developed as characteristic stout spines very closely approximated to each other, third dorsal cilium a short spine, and all the rest unde- veloped. Proximal barbules (pl. 20, fig. 20b) with base of moderate size, about 0.5 by 0.05 mm., with short, inconspicuous ventral teeth; pennulum only a little shorter than base, shghtly flattened proximally, but soon tapering to a very fine slender filamentous tip. Outer vane.—Distal barbules (pl. 20, fig. 20c) with pennulum somewhat shorter and stouter than in inner vane, usually 6 hooklets, no dorsal cilia, and a large number of short, blunt ventral cilia. Proximal barbules (pl. 20, fig. 20d) differ from those of inner vane only in having a somewhat shorter pennulum; no ventral cilia ever developed. (2) Other Feathers Inner scapular feathers with distal barbules (pl. 20, fig. 20e) somewhat like those of distals of outer vane of remiges, but both base and pennulum more elongated, pennulum also stouter, more like ciconiid type, with short, broad, and very blunt ventral cilia somewhat resembling ventral teeth; pigment irregularly distributed, being dense in base, but very light or absent in pennulum. Proximal barbules of scapulars (pl. 20, fig. 20f) differ from those of outer vane of remiges only in more elongate and relatively slender form. Blunt ventral cilia of distals of outer vane slightly more numerous and better developed, otherwise vanes alike. Elongated tips of these feathers produced by an elongation of the slender shaft accompanied by a number of greatly elongated barbs lying so closely appressed, and attached to shaft at such long intervals, as to le paral- lel with shaft. These elongated barbs are furnished with distal and proximal barbules only slightly reduced, so that they interlock fairly well. On account of change in angle of insertion of more distal barbs, there is too much strain for perfect vane to be maintained, result being a breaking up into elongated groups of barbs, which is very charac- teristic of these feathers. On breast feathers also with elongated, ornamental tips, basal portion of feathers has much simplified barbules, and barbs very loose if at all held together. Barbs of ornamental tip better developed with less simplified barbules, the latter resembling those of scapular and back feathers, being short, with well-developed functional hooklets. As in back feathers, barbs inserted at wide intervals, and closely appressed to one another so as to form a very narrow, compact tip. b) Other Types Nycticorax nycticorax differs from Ardea herodias in the strue- ture of its remiges only in the slightly better developed third dorsal 1916] Chandler: Structure of Feathers 323 cilium, and presence of a rudimentary fourth one. The dark green feathers of the back are somewhat modified. The bases of both distal and proximal barbules of these feathers are lone and nar- row, and deeply pigmented, while the ventral teeth in both are poorly formed and lightly pigmented. The hooklets of the distals are weak and reduced, the ventral cilia are short and blunt, and there are no dorsal cilia. The proximals have three or four progressively diminishing blunt ventral cilia on the pennulum, thus ereatly resembling in general form the distal barbules. Botaurus and Butorides very closely resemble Ardea in all the details of their feather structure. The distal and proximal barbules of the outer vane of Butorides virescens are shown in plate 20, figures 21a and 21b, and comparison with figures 20a and 206 of the same plate will show the similarity. The sheht separation and for- ward curve of the ventral teeth of the proximals of the distal part of the outer vane, as shown in plate 20, figure 21b and slightly less prominently in plate 20, figure 20d, are very characteristic of the entire family. The most interesting birds of the entire group from a popular point of view are the egrets, Egretta candidissima and Herodias egretta, from which are derived the famous ‘‘aigrettes’’? of com- merce. In the structure of its remiges Herodias egretta differs from the typical forms of the genus Ardea in the reduction of the dorsal cilia. The first one is fairly well developed, the second smaller, and the third very minute. They thus differ from Ardea herodias in the opposite direction from Nycticorax, which has the dorsal cilia a little better developed. The aigrettes of both species of egrets are too well-known to need a general description, the barbs being very widely separated on the shaft, reaching a length of 15 em. or more, and appearing as filamentous strands entirely separate from each other. Although to the naked eye the barbs appear destitute of barbules, closer examina- tion shows that there is a complete series of closely appressed, non-interlocking barbules, the distal and proximal ones very similar, except that the latter are a little longer. They are flat and taper- ing, with no well-developed barbicels, as shown in plate 20, figure 22. The distal and proximal barbules are spaced 21 and 18 per milli- meter respectively. The barbules of the aigrettes of Herodias egretta differ from those of Egretta candidissima in the length, the former being under 0.65 mm. long while the latter are normally at least 0.7 324 University of California Publications in Zoology ‘Vou. 18 mm. and usually a httle over 0.8 mm. In the aigrette-like feathers of Bubuleus ibis of Europe there are only 11 proximal barbules and 14 distals per millimeter, and they never exceed about 0.57 mm. in length. These barbicels are even more rudimentary than in the true American egrets. Eurypyga (see p. 352, and pl. 27, figs. 55a-d) and _ possibly Cariama (p. 352, and pl. 27, figs. 56a and b) are probably nearly related to the Ardeae. Cuwrsorius, family Glareolidae (p. 356, and pl. 28, figs. 60a-c), also appears to be most nearly related to the Ardeae. c) Down The down barbules in Ardea are long, reaching a length of 2 mm. or more, being filamentous and very slender, with slightly enlarged nodes, and pigment uniformly, or almost uniformly, distributed. Minute prongs present at nodes on more distal portion of barbules. In Botaurus, 1 which the down is dark gray, the pigment is absent only at the nodes (pl. 34, fig. 100). d) Relationships The Ardeae, or at least the Ardeidae, seem to form an end branch from a ciconiid stem, being considerably more specialized than the Ciconiae, and apparently not giving rise to any other orders or suborders. Hurypyga, and to a less extent, Cariama, both ordinarily classed in the Gruiformes, have a feather structure which is so heron-like that the possibility of their inclusion in the Ardeae is strongly suggested. Cursorius likewise has a structure which strongly argues for its inclusion in this group. e) Summary The typical Ardeae have the following epiphyological characters : (1) Plumules confined to apteria. (2) Aftershaft present. (3) Powder down present. (4) lLores naked. (5) Distal barbules nearly twice as numerous as proximals. (6) Distal barbules of remiges with small base, with large, leaflike ventral teeth, so shaped and arranged as to form a large cr blunt triangle; hooklets usually 5, only 3 or 4 progressively dimin- 1916] Chandler: Structure of Feathers 325 ishing ventral cilia developed, and on inner vane two closely approximated, blunt, stout, dorsal cilia followed by one or two spinelike ones, the rest of the pennulum elongated, slender, and without barbicels. (7) Proximal barbules of inner vane with moderately large base, short inconspicuous ventral teeth, and pennulum very slender and threadlike, shorter than base. (8) Proximals of outer vane similar to those of inner vane, never developing ventral cilia. (9) Bedy feathers with pennulum of distals usually rather stout, dorsal cilia not developed, the ventral ones conspicuously short and blunt. (10) Ornamental plumes with divided vanes frequently de- veloped. (11) Down very long, often over 2 mm., the nodes slightly enlarged, sometimes with minute prongs, pigment when present not collected into conspicuous spots. IV. SusorpDER PHOENICOPTERI Pini Rigs 32 The flamingoes, in Knowlton’s classification, are grouped as a suborder of the Ciconiiformes, but in their characters they are so perfectly transitional between the Ciconiae, especially the ibises, on the one hand, and the Anseriformes on the other, that, while evidently forming a suborder of their own, the question as to the group with which they are more closely associated has been one of the most debated questions in the classification of birds. Their feather structure, therefore, is of unusual interest, on account of the light which it throws on this relationship. As in both the Ciconiae and the Anseriformes, the down is here also uniformly distributed. The aftershaft is present, which is an interesting fact considering that in the Ciconiae it is very variable, while in the Anseriformes it is rudimentary or absent. There are twelve primaries as in some Ciconiae, whereas in Anseriformes there are only eleven. a) Phoencopterus ruber (1) Remex Shaft of remiges slightly wider than deep, with shallow median groove. Pith of rami more than one cell in thickness; whole ventral 326 Unversity of California Publications in Zoology Vor. 13 ridge narrow, and without villi on the ventral edge on outer vane. Distal barbules small relative to the proximals, and outnumbering them about two to one; on inner vane of secondary about 40 distals to 20 proximal barbules per millimeter. Inner vane—Distal barbules (pl. 21, fig. 32a) with very short base, about 0.2 mm. long by about 0.04 mm. wide; ventral teeth slender and elongate, much more so than in Ciconiae, but less so than in Anseres; the pennulum relatively short, seldom over 0.3 mm., making, with the base, a short barbule; hooklets 5, slender, of moderate length, but progressively longer; ventral cilia long and slender, and not conspicuously curved; dorsal cilia, as a_ series, well developed, the basal 2 or 3, stout and spiny, the more distal ones more slender. Proximal barbules with base about 0.5 mm. long by 0.055 mm. wide, with a series of about 4 ventral teeth, the proximal two larger and more lobate, the outer ones more slender and pointed. Outer vane.—Distal barbules differ mainly in the larger number of hooklets, and more conspicuous ventral cilia, and absence of dorsal ones, while in proximals (pl. 21, fig. 32b) the ventral teeth, especially distal ones, become separated from each other, increase in number, and form a series of straight, sharp, ventral barbicels, exactly comparable to those in the outer vane of ducks, as will be seen by comparing plate 21, figure 32b, with plate 21, figure 28/. (2) Other Feathers. In body feathers barbules merely a simplification of remex type, proximals retaining a series of slender, ventral barbicels, as shown in plate 21, figure 32c, which represents a proximal barbule from loose- vaned scapular feather; no flexules ever developed. (3) Down Down barbules (pl. 35, fig. 102) long and filamentous, with inconspicuous nodes except near tip of pennula, where they are slightly enlarged, and possess small prongs. b) Relationships and Summary In all of the above details of the minute structure of the feathers the Phoenicopteri agree with the Anseres more closely than with the Ciconiae. In all of the following points they agree with the Anseres as opposed to the Ciconiae: (1) general shape and relative size of barbules; (2) form of ventral teeth of both distals and proximals; (3) form of both ventral and dorsal cilia of distals; (4) presence and form of ventral barbicels of outer proximals. The chief points of difference are: (1) the smaller number of hooklets; (2) the smooth ventral edge of rami of outer vane; (3) form of down. In the first two of these characters they also differ from the Ibididae, with which they are more closely related than ~) 1916] Chandler: Structure of Feathers 32 with any other Ciconiae, and in the third they are intermediate between the Ciconiae and the Anseres. 5. Order ANSERIFORMES Pl. 21, Figs. 28-31 Comprising the two suborders Anseres and Palamedeae, this order is characterized by the uniform distribution of plumules, and the absence or rudimentary condition of the aftershaft. The Pala- medeae are further characterized by the total absence of apteria, a condition found elsewhere only in the Sphenisciformes among carinate birds. Since in the finer structure of their feathers the two suborders have little in common, it will be more advantageous to take them up separately. I. Suborder ANSERES Pl. 21, Fig. 28-30 a) Anas platyrhynchos (1) Remex Calamus unusually long, being considerably over one-third length of quill in primaries. This elongation is a very constant and char- acteristic feature. Shaft about as broad as deep, with broad, shal- low ventral groove. Rami with rather broad attachment to shaft, especially on outer vane, and differing from all other birds except a few gallinaceous species, in the enormous development of ventral ridge into a broad, thin, filmlike expansion on the basal one-third to two-thirds of the barb, reaching over and adhering to the adjacent ramus in front of it, producing a very conspicuous macroscopic effect on lower side of feather, where the portion of feather plate involved has a shiny, glazed appearance. Plate 21, ficure 28a, represents proximal portion of barb from inner vane of a primary, showing expanded ventral edge with filmy expanded ventral ridge ending abruptly. On outer vane, rami further char- acterized by dense villi (pl. 21, fig. 28b). Distal and proximal vanules with barbules not as different in size as in Ciconiae but distals outnumbering proximals nearly as much as in latter group; about 42 distals and 23 proximals per millimeter on a barb from inner vane of primary. Inner vane——Distal barbules (pl. 21, fig. 28c) relatively large for size of feather, base about 0.27 by 0.042 mm., extremely thin and filmy, pigment usually absent below line of nuclei, although this area is wider than usual; ventral teeth lobate but not blunt or truneate at end, being drawn out more or less into slender points. Hooklets exceedingly slender and delicate, with their hooked tips somewhat enlarged, usually 6 or 7 of them, progressively and regularly becoming longer; ventral cilia long, slender, and not 328 Unwersity of California Publications in Zoology Vor. 18 appressed. Dorsal cilia forming a well-developed series, basal ones stouter and spinelike, but not as strongly contrasted with others as in Ciconiae. Proximal barbules (pl. 21, fig. 28d) also thin and filmlike, with little pigment; base unusually slender, about 0.65 by 0.04 mm. Proximal two ventral teeth broad, lobate, and blunt, followed by two or three narrow and pointed ones; pennulum little shorter than base, with rudimentary barbicels always showing. Outer vane—Distal barbules (pl. 21, fig. 28e) with drawn-out points of ventral teeth more prominent; hooklets even more slender, and increased in number; dorsal barbicels absent. Proximal bar- bules on outer portion of barb with ventral teeth proliferated and transformed into straight ventral barbicels, resembling teeth of a comb (pl. 21, fig. 28f). (2) Other Feathers As in nearly all ducks, greater wing coverts form a speculum of different color from rest of wing, in this case deep bluish violet. For production of this color, as of other metallic colors, e. g., blues and greens of various species, the pennula are transformed into flattened refrangent surfaces (pl. 21, fig. 287) with constrictions between cells, and fine, longitudinal striations on cells, which are deeply pigmented with black. Base and hooklet region considerably reduced in these metamorphosed barbules. Barbules of inner vane of speculum feathers, and proximals of outer vane also, unmodified. As described at close of Part I (p. 279), modifications of distal barbules are absent in albinos. Body feathers rather loose in texture, due largely to fact that bases of barbules le in vertical plane, leaving wide spaces between them. Ventral teeth of distal barbules greatly reduced, but slender, subequal cilia still numerous and well formed. Just distal to hook- let region, pennulum twists so that ventral cilia come to project dorsally. Proximals have slender, tapering bases, inconspicuous ventral teeth and rudimentary prong-like cilia. The poorly de- veloped tail feathers intermediate in form between remiges and body feathers. Their form is shown by plate 21, figures 28g and h. b) Other Types The minute structure of the feathers is remarkably constant in all the members of the Anseres. Nettion carolinense is perhaps slightly more typical of the group in that the ventral teeth of the distal barbules are greatly elongated and slender, as shown in plate 21, figure 29a. Marila, Mergus, Querquedula and other genera are almost identical with Nettion. Branta, like Anas, has the ventral teeth of the distals somewhat shorter, while some of the feathers have the pennula of the distals of the outer vane elongated with long brushlike cilia to produce the characteristic plush-like effect. Chen very closely resembles Branta, 1916] Chandler: Structure of Feathers 329 but the barbicels of the proximals of the outer vane are stouter and more irregular. Olor columbianus has the elongation of the ventral teeth of the distals less extreme, as in Anas, and has the hooklets even more slender than in typical ducks and geese. Speculum feathers occur in a very large number of genera, espe- cially of ducks, sometimes being white, but frequently some iridescent color, as blue, green, or violet, the structure in these cases being of the type described above for Anas platyrhynchos. A distal barbule from the brilliant green portion of a speculum feather of Nettion carolinense is shown in plate 21, figure 29b. The deep velvety black scapular feathers of Mareca, which are tinged with metallic green, have distal barbules in which the base as well as the pennulum takes part in the color effect (pl. 21, fig. 30a). c) Down The down barbules of all typical ducks are short, seldom over 1 mm. long, and usually considerably less. They are simple and thread- like for the greater part of their length, but on the basal half of the barbs there are developed at the tip of the barbules 3 or 4, sometimes 5, very conspicuous expanded nodes followed by a slender tip (pl. 35, fig. 104). On the outer portion of the barbs these enlarged nodes are reduced and there are a few terminal pairs of prongs taking their place. The number of terminal nodes differs to some extent in dif- ferent species, e. g., Anas has 2 or 38, Mareca 3 to 5, and Mergus 2 to 4. In Branta there are 4 to 6, which are not so large and are farther separated. In Olor they are still more separated, less con- spicuous, and the transitional nodes on either side are better devel- oped (pl. 35, fig. 103). d) Relationships The feathers of the Anseres show high specialization in a num- ber of points of their microscopic morphology, and are unques- tionably to be regarded as the end of one line of evolution. The typical ducks show the specialized characters in their highest develop- ment, the geese, as represented by Branta and Chen, being lower in the scale, and the swans, as represented by Olor, still lower and form- ing a more or less natural bridge over the gap between the more typical Anseres on the one hand, and the Phoenicopteri on the other. 330 University of California Publications in Zoology Vor. 18 e) Summary The Anseres are characterized as follows: (1) Plumules evenly distributed. (2) Aftershaft rudimentary or absent. (3) Rami of remiges with extremely broad filmlike ventral ridges, furnished with dense villi on the ventral edge on the outer vane. (4) Barbules of remiges and body feathers essentially the same, the latter merely simplified. (5) Distal barbules with elongated ventral teeth and very slender hooklets. (6) Proximal barbules of inner vane with slender base, 2 prox- imal ventral teeth blunt and lobate, the others narrow and pointed, and a moderately long filamentous pennulum with pronglike rudi- mentary barbicels. (7) Proximals of outer vane with a series of straight, pointed cilia on the pennulum. (8) Down barbules short, with nodes undeveloped, except 3 to 6 or 8 near tip which are very highly developed. Suborder PALAMEDEAE Pl. 21, Fig. 31 The two genera constituting this group, Palamedea and Chauna, differ in a number of important details of feather structure from the Anseres. In Chauna cristata the barbs are heavily built, the pith more than one cell in thickness, and with only a narrow translucent ventral ridge. The distal barbules (pl. 21, fig. 31a) of the outer vane, the only ones which I have obtained for study, are characterized by a large, stout base with broad, lobate ventral teeth, reminiscent of the Meleagridae, and by a fairly short pennulum with a very large series of long slender hooklets, usually eight in number, followed by only a few slender ventral barbicels. The proximals (pl. 21, fig. 31b) have large, stout bases with the ventral teeth as in the Anseres (i. e., the first two more lobate than the others), and a short, rather broad pennulum as in the Ciconiae and also some Galli. The back feathers are of a rather peculiar nature, the pennula being greatly elongated to give the characteristic hoary appearance. The base is long and tapering, the hooklets usually five, subequal in size, followed by a complete series of ventral cilia, also of approx: 1916] Chandler: Structure of Feathers 331 imately equal size. The long barbicelled pennulum is without pigment, resulting in the hoary appearance above mentioned. The breast feathers have a much simplified type of barbules, with a series of hooklets and curved ventral cilia which grade into each other and are all subequal in size. The pigment is distributed in well-defined transverse bars. The down barbules, unlike those of the Anseres, are long, 2 mm. or more, being almost simple threads, a few inconspicuous prongs being developed at the nodes. As will be seen from the above, the Palamedeae are peculiar in that they combine the characters of a number of other groups of birds in a confusing manner and could not readily be associated with any group on the basis of their feather structure. The distal barbules of the remiges resemble those of the Anseres in number and form of the pennular barbicels, but the ventral teeth are most closely paralleled by the Meleagridae; proximals of the remiges combine anserine, ciconiid, and galline characters; the barbules of the breast feathers constitute a type of their own, probably de- generated; and finally the down barbules are long and threadlike, unlike either Anseres or Galli, but near the Ciconiidae. 6. Order FALCONIFORMES Plates 22, 23 The Falconiformes. include a rather well-defined group divisible into three distinct suborders, which, as in the case of Anseriformes and Ciconiiformes, can more readily be treated separately. As an entire group they show unmistakable evidence of being derived from a parent stock somewhere intermediate between the Stegano- podes and Ciconiae. In the entire order the plumules are uniformly distributed, powder down is present in a few, and the aftershaft is present in all but the Cathartae, which, however, seem otherwise to be the lowest in the evolutionary scale. I. Suborder CATHARTAE Pl. 22, Fig. 34 a) Gymnogyps californianus (1) Remiges Barbs moderately broad, but very heavily built, pith of rami more than one cell in thickness. Barbules large, the distals larger than usual relative to proximals. Fewer barbules per unit of 332 Unwersity of California Publications in Zoology 'Vour. 18 measure than in any group previously studied, about 28 distals and 12 or 13 proximals per millimeter. Inner vane—Distal barbules (pl. 22, figs. 34a, 34b) with large bases, about 0.4 mm. long by 0.05 mm. wide. Stout base of the distals furnished with moderate, lobate ventral teeth; the pennulum stout, with about 5 stout, progressively longer hooklets, followed by a few long, slender ventral cilia, the distal portion devoid of them. Two basal dorsal cilia developed as in Plotus, forming stout, blunt, laterally projecting, spinelike processes; all the other dorsal barbi- cels rudimentary. Distal to these characteristic dorsal cilia there is a bend in dorsal contour of barbule as shown in the figures. When detached, barbules usually lie in the position shown in plate 22, figure 34b. Proximal barbules (pl. 22, fig. 34c) with relatively small bases, a series of moderate ventral teeth, and pennulum which is broad proximally, but rapidly tapering to fine thread. Pennulum somewhat shorter than base. Outer vane.—Distals (pl. 22, fig. 34d) differ from those of inner vane mainly in possessing larger number of hooklets, in greater development of ventral cilia, and in absence of dorsal ones. Prow- imals, as Shown by plate 22, figure 34e, very similar to those of inner vane, but slightly larger, and ventral teeth a little more prominent, at extreme tip becoming shghtly more separated from one another and assuming more of a toothliike form. Typical ventral cilia not developed. b) Other Types Cathartes aura has practically the same types of barbules, though smaller and the barbicels not so stout. On the broad basal portion of the primaries, the proximal barbules at the tip of the barbs have the ventral teeth transformed into toothlike cilia, but they are not proliferated and do not become slender or hooked. The back feathers of Cathartes aura have barbules resembling those of the outer vane of the remiges, the distals differing in havy- ing a very stout heavy pennulum, with fewer and more slender teeth, and with stout appressed ventral cilia. The breast feathers have the barbules very much simplified and reduced. No flexules are ever developed. c) Down The down barbules of Cathartae are very long and _ slender, with the nodes only marked by slight enlargements, showing best on the proximal vanule, the internodes being very long. The bases of the down barbules are hardly differentiated from the pennula, being very narrow. 1916] Chandler: Structure of Feathers 333 d) Relationships The Cathartae show many characters in the minute feather struc- ture which appear to show rather close alliance with the Steganopodes, and in one particular, namely in the nature of the distal barbules of the inner vane, show an astonishing likeness to Plotus. This is a char- acter which could easily have arisen separately in the two groups, as it undoubtedly has done in other cases, e. g., the Bucerotidae, but the other likenesses between the Cathartae and the Steganopodes as a group make it more probable that Plotus and the Cathartae had a common ancestor. As will be shown below, the present group differs considerably from the Accipitres but the gap is bridged to some extent by the Gypogerani and Vulturidae. e) Summary The main characters of the Cathartae are as follows: (1) Barbules relatively widely spaced on the barb, and of large size. (2) Distals of remiges characterized by large stout base, mod- erate ventral teeth, heavy pennulum, and a series of progressively longer stout hooklets, followed by a few large, more or less appressed ventral cilia, the dorsal cilia being reduced to 2 stout, blunt, spine- like, basal ones immediately beyond which there is a conspicuous bend in the barbule. (3) Proximals with moderate base and ventral teeth, pennulum shorter than base, and with no cilia on either inner or outer vane. (4) Down barbules long and slender, with long internodes and very inconspicuous nodes. II. Suborder GyYPoGERANI Pl. 22, Fig. 35 Though in general appearance the secretary birds are farther removed from typical Accipitres than are the American vultures, in feather structure they have a much closer resemblance. a) Gypogeranus serpentarius (1) Remex Inner vane—Distal barbules (pl. 22, fig. 35c) more or less inter- mediate in form between those of the other suborders of this group. Base and ventral teeth moderate, hooklets 5 in number, and slender as in Faleonidae, ventral cilia slender and rather inconspicuous, 334 University of California Publications in Zoology Vor. 18 and dorsal cilia, except basal two, rudimentary. The latter not so stout or so close together as in the Cathartae but more so than in the Faleonidae. Proximal barbules (pl. 22, fig. 35d) relatively small and of typical faleonid type. Outer vane.—Distal barbules differ from those of inner vane in the greater length of the hooklets and in the shorter cells of the pennulum, the latter resulting in the close approximation of the ventral cilia, so that they appear brushlike. Proximal barbules have well-developed, hooked ventral cilia, as in Accipitres. Distal to the incision of the feather, where vanes are narrowed, distal barbules of inner vane do not possess dorsal barbicels, and proximal barbules of outer vane do not have hooklike ventral cilia. The latter are developed but lie closely appressed to the barbule. (2) Back Feathers Gray back feathers of Gypogeranus with distal barbules with relatively large pennula, furnished with small, rather weak hook- lets and long, slender, closely set ventral cilia. Pigment concen- trated in spots, resulting, as in gulls, in bluish tinge in gray color (pl. 22, figs. 35a, 35D). (3) Down The down barbules do not materially differ from those of other Faleoniformes, being moderately elongate, reaching a length of 2 mm. or more, the base poorly developed, and pennula very slender with slightly enlarged nodes, which, especially at tip, are furnished with short, inconspicuous prongs. b) Summary and Relationships The Gypogerani are much nearer to the Accipitres than to the Cathartae as far as feather structure is concerned. They agree more closely with the Cathartae in the character of the dorsal cilia of the distal barbules of the inner vane, but in all other details of structure they are almost identical with the Accipitres. III. Suborder AccIPITRES The birds of this suborder form a compact, well-defined group, including the hawks, eagles, ospreys, and Old World vultures. The owls used to be associated with this group until further investigation showed that they were in reality widely separated, with many points in common as the result of parallel evolution and similar adapta- tion. The morphology of the feathers agrees with the osteology, myology, and other characters in showing that the Striges really have nothing in common with the Accipitres as regards near rela- tionship. As in other Falconiformes, the plumules of the Accipitres are uniformly distributed, and in a few forms powder-down is present. The aftershaft is present, and usually well developed. 1916] Chandler: Structure of Feathers 335 a) Buteo borealis (1) Remiges Shaft about as wide as deep, quadrangular, with well-developed ventral groove. Vanes notched or incised on outer vanes, the rami of outer vane beyond point of incision as wide as shaft is deep, the pith more than one cell in thickness, with moderate ventral ridge, with villi on ventral edge. Proximal vanule with over two- thirds as many barbules as distal vanule, there being 28 to 30 distal barbules and 22 to 23 proximals per millimeter, the latter small relative to distals. Inner vane-—Distal barbules (pl. 23, fig. 38a) with long, slender base, about 0.38 by 0.06 mm., with relatively small, but broad and lobate ventral teeth; pennulum much longer than base, with 5 slender, moderately long hooklets, which progressively increase in length, a well-developed series of slender, filamentous ventral cilia, and a series of slender dorsal cilia, the basal ones stouter and more spinelike, but not lobate as in the Cathartae. Proximal bar- bules (pl. 23, fig. 38b) with base relatively small as compared with distals, about 0.75 by 0.07 mm., with 4 or 5 short, poimted ventral teeth and moderately slender pennulum, a little over half as long as base. Outer vane—Distal barbules much like those of inner vane, but base shorter and relatively stouter, pennulum shorter, the hooklets usually 6 in number, and relatively longer, and no dorsal cilia. Proximal barbules (pl. 23, fig. 38¢) on terminal portion of barbs with a series of highly developed hooked ventral cilia, basal ones, representing ventral teeth, short and triangular, middle ones almost like hooklets of distal barbules, outer ones smaller, weak, and _fila- mentous. (2) Other Feathers Back feathers have structure differing from remiges chiefly in simplification. Barbules more slender, especially base, all the barbi- cels considerably reduced and vanules open, 1. e., with spaces between barbules, which stand in vertical plane relative to surface of barb (see plate 23, figures 41a and 41b, representing barbules from back feather of Falco rusticola). Breast feathers similar, but still more simplified, the bases of barbules very elongate and slender and all barbicels greatly reduced. b) Other Types Examination of a large number of species of different sections of the suborder shows that there is little variation in the form of the barbules. Feathers of species of Buteo, Circus, Haliastur, Archibuteo, Spizaetus, Haliaeétus, Aquila, Elanus, Falco, Pandion, Polyborus, and Gyps have been examined, and no striking devia: tions from the type described have been found. In the distal bar- bules of Falco peregrinus (pl. 23, fig. 36a) the pennulum is rela- 336 Unwersity of California Publications in Zoology Vou. 18 tively short, but the vroximals, (pl. 23, figs. 36b, 36c) almost exactly as in Buteo. Falco sparverius, again, has a long pennulum on the distal barbules. In Haliaeétus leucocephalus the pennulum of the distals is short, and the basal dorsal cilia unusually stout (pl. 23, fig. 39a). The proximals (pl. 23, fig. 38b) have longer and more prominent ventral teeth than in Buteo. Polyborus cheri- way agrees with Haliaecétus in the small pennulum and spinelike dorsal cilia of the distal barbules (pl. 28, fig. 40a). The structure of the feathers of Circus hudsonius was worked out in detail by me (1914) ; they agree with Buteo in all important details. In Gyps fulvus, representing the Vulturidae, the barbules of the outer vane of the remiges differ considerably from the type, as shown by plate 22, figures 33c and 33d. The distal barbules have enormously developed hooklets and ventral cilia, giving the barbule a very unique appearance. The proximal barbules on the terminal portion of the barbs do not acquire hooked cilia as in other Accip- itres, but differ from those of the inner vane merely in the slight proliferation of the ventral teeth, which are only partially trans- formed into cilia, as shown in plate 22, figure 33d. The back feathers of this species differ from those of more typical accipitrines only in the great width of the pennulum of the distal barbules (pl. 22, figs. 38a, 330). c) Down The down barbules are very variable, even within a single genus. In the majority of the group, e. g., Accipiter cooperi, Pandion carolinensis, Circus hudsonius, Buteo borealis, and Gyps fulvus, the barbules are elongate and very slender, with very slight swell- ings at the nodes, and short prongs toward the tip. In Falco, how- ever, the nodes are more enlarged, not conspicuously so in F. ruste- cola or F. peregrinus but strikingly so in F. sparverius where the pigmentation is in deep nodular spots. As shown in plate 35, figure 105, the internodes are very slender and frequently wavy, the latter condition being very unusual in down barbules. d) Relationships The microscopic morphology of the feathers of the Accipitres presents many points which are difficult of interpretation. Admit- ting their relationship with the Cathartae, which seems to be 1916] Chandler: Structure of Feathers 337 plainly indicated by other features in their anatomy, and is made rather easy, even taking into consideration the structure of their feathers, on account of the intermediate condition of Gypogeranus, the Accipitres must be regarded as derivatives of a Steganopode- like bird. Yet in the form of the ventral cilia of the proximal bar- bules, and of ventral teeth, hooklets, and dorsal cilia of the distals, they come very close to the Galli. The down of some resembles that of the Steganopodes while that of others, e. g., Falco sparverius, resembles that of some Coraciiformes. However, all of these points of resemblances are features which could easily be conceived of as having been developed more than once, and it seems best to regard the Accipitres as derivatives of the Steganopodes through the Cathartae and Gypogerani. e) Summary The Accipitres are characterized as follows: (1) Distal barbules of inner vane of remiges with relatively large base, lobate ventral teeth, 5 hooklets, slender filamentous ventral cilia, and slender dorsal cilia, the basal ones spinelike ; pennulum frequently much longer than base. (2) Distals of outer vane with shorter base, and relatively shorter pennulum with shorter cells, making a brushlike series of ventral cilia. (3) Proximals of inner vane with relatively small base, short pointed ventral teeth and moderately long pennulum. (4) Proximals of outer vane, on distal half of barb, with well- developed series of hooklike ventral cilia. (5) Body feathers differing from remiges only in simplification, and slender form of barbules. (6) Down barbules very fine and slender, the nodes more or less enlarged, sometimes pigmented. 7. Order GALLIFORMES Plate 24 Comprising a very large assemblage of the so-called ‘‘game- birds,’’ the present order is subdivided into four suborders as fol- lows: (1) Mesaenatides, represented only by the kagu or mesite of Madagascar; (2) Gall, including the megapodes, curassows, pheasants, partridges, turkeys, etc.; (8) Turnices, including the Hemipodes of the Old World; and (4) Opisthocomi, to which belongs only the peculiar Hoactzin of South America. 338 University of California Publications in Zoology (Vor.18 Unfortunately, I have been unable to secure feathers of the first and fourth suborders for examination, and the relationships sug- gested by their feather structure cannot, therefore, be discussed. The other two groups, Galli and Z'urnices, though in superficial appearance very similar, differ in so many details of feather strue ture that they may more advantageously be considered separately. I. Suborder GALLI Pl. 26, Figs. 42-47 Though containing a very large number of species and genera, this suborder forms a fairly compact and well-defined group. In general they are characterized by the restriction of the plumules to the apteria, and by the variability of the aftershaft. In some members of the group, e. g., Bonasa, the latter is better developed than in any other group except Casuariiformes, while in others, e. g. Pavo, it is very small and almost rudimentary. a) Gallus domesticus (1) Remez Shaft slightly wider than deep, with a broad, conspicuous ventral eroove; calamus, in contrast to the condition found in Anseres, short, not greatly inflated, its caliber less than that of the shaft. Vanes firm, barbs of the inner vane set about 18 per centimeter, those of outer vane considerably less, especially in the primaries. Vanules with barbules very close set, about 40 distals and 32 prox- imals per millimeter in a typical portion of the feather, this number of proximals being larger relative to the number of distals than in most water-birds. Inner vane.—Distal barbules (pl. 24, fig. 42a) with base about 0.26 mm. in length by 0.04 mm. in width, the pennulum about the same length. Base rather broad and quadrangular, with usually 3 ventral teeth, these in the form of broad lobes, very thin and film- like. Nuclei in a conspicuously diagonal line, on account of the short, broad form of the base, with its broad ventral teeth. Pen- nulum with 6 to 8 hooklets of moderate size, progressively mereas- ing in length, not slender with enlarged hooks, as in Anseres, but stouter basally. Ventral cilia of moderate size, not flexible or appressed, but in the form of stout, strongly curved, hooklike processes, decreasing in size toward the tip, but relatively well developed on the whole length of the pennulum; 3 or 4 sharp, spinelike, dorsal cilia, not, however, highly modified as broad lobate or hoodlike projections. More distal cells of the pennulum with short, pronglike, rudimentary dorsal cilia. Proximal barbules (pl. 24, fig. 42b) with slender base, about 0.6 mm. long by 0.05 mm. wide, with a series of short, pointed, lobate ventral teeth. Pennulum remarkably short, especially on 1916] Chandler: Structure of Feathers 339 more basal portion of barb, for the most part not exceeding one- third the length of the base, broad basally, tapering rapidly to a slender but short filament. Outer vane.—Distal barbules (pl. 24, fig. 42c) even shorter than on inner vane, total length under 0.5 mm., the base constituting about one-half of this. Base slightly curved longitudinally, with lobate ventral teeth not as broad as in inner vane. Pennulum with hooklets about as in the inner vane. Ventral cilia more nearly sub- equal to each other for the whole length of the pennulum, strongly curved, and well separated from each other. Dorsal cilia in the form of short prongs. Proximal barbules on proximal portions of the barbs closely resembling those of the inner vane, but pennulum even shorter. On the outer portion of the barbs, the proximals (pl. 24, fig. 42d, 42e) with ventral teeth proliferated and transformed into a series of stout, strongly hooked ventral cilia, in some cases almost exactly like hooklets in form, more numerous on more distal barbules, but only 3 to 5 basal ones strongly hooked. (2) Other Feathers Body feathers, where there are no special color modifications, merely simplifications of remex type, distal barbules resembling outer vane type, proximals the inner vane type. Vanes not firmly interlocking and usually a large portion of feather downy. < a aS = \ Sr SS ee SH awe LLNS Fo a IES = — PP se] Sil i, v y pe ats He1, 58 - ae fale 7 Fig. 10. gases 1st, dite 8 s ¢ Fig. 1 SAR PLATE 17 PROCELLARITFORMES All figures & 100 Diomedea exsulans. Distal barbule from inner vane of remex, Proximal barbule from same. Distal barbule from outer vane of remex. Proximal barbule from same, distal third of barb. Distal barbule from outer third of barb of breast feather. Puffinus griseus. Distal barbule from inner vane of remex. Proximal barbule from same. Proximal barbule from outer vane of remex, distal third of barb. Oceanodroma melania. Distal barbule from near tip of barb of breast feather. Proximal barbule from same. [406] [CHANDLER] PLATE 17 UNIV. CALIF. PUBL. ZOOL. VOL. 13 Fig. 18. angagoces Hig dss PLATE 18 STEGANOPODES All figures « 100 Plotus anhinga. Distal barbule from inner vane of remex. Proximal barbule from same. Distal barbule from outer vane of remex, silvery gray portion. Proximal barbule from same, distal third of barb. Distal barbule from back feather, silvery gray portion, Distal barbule from back feather, black portion. Proximal barbule from back feather, about middle of barb. Phalacocoraz penicillatus. Distal barbule from inner vane of remex. Proximal barbule from same. Distal barbule from outer vane of remex. Proximal barbule from same, distal third of barb. Distal barbule from back feather, velvety portion. Proximal barbule from same. Fregata aquila. Distal barbule from inner vane of remex. Proximal barbule from same. [408] [CHANDLER] PLATE 18 UNIV. CALIF. PUBL. ZOOL. VOL. 13 —_. on ae Fig. Fig. Fig. Fig. “+e aogss PLATE 19 STEGANOPODES, continued All figures & 100 Sula variegata. Distal barbule from inner vane of remex. Poximal barbule from same. Distal barbule from back feather. Proximal barbule from same. Pelecanus erythrorhynchus. Distal barbule from inner vane of remex. Proximal barbule from same. Proximal barbule from outer vane of remex. Distal barbule from breast feather, distal third of barb. Proximal barbule from breast feather, proximal third of barb. Pelecanus californicus. Distal barbule from back feather, velvety portion. Phacthon flaviventris. Distal barbule from inner vane of remex. Poximal barbule from same. Distal barbule from outer vane of remex. Proximal barbule from same, distal third of barb. Distal barbule from breast feather, near tip of barb. Proximal barbule from same. [410] [CHANDLER] PLATE 19 UNIV, CALIF, PUBL. ZOOL. VOL. 13 Fig. Fig. Fig. Fig. Fig. Fig. Fig. Fig. PLATE 20 ARDEAE AND CICONIAE All figures & 100 Ardea herodias. Distal barbule from inner vane of remex. Proximal barbule from same. Distal barbule from outer vane of remex. Proximal barbule from same, distal third of barb. Distal barbule from back feather, basal third. Proximal barbule from same. Butorides virescens. Distal barbule from outer vane of remex. Proximal barbule from same, distal third of barb. Egretta candidissima. Barbule from “aigrette.” Mycteria americana. Distal barbule from inner vane of remex. Proximal barbule from same. Distal barbule from outer vane of remex. Distal barbule from breast feather. Leptoptilus dubius. Distal barbule from inner vane of remex. Distal barbule from outer vane of remex. Plegadis guarauna. Distal barbule from inner vane of remex. Guara (Budocimus) ruber. Distal barbule from scarlet back feather. Ajaja ajaja. Distal barbule from back feather. [412] [CHANDLER] PLATE 20 UNIV. CALIF, PUBL. ZOOL. VOL. 13 Fig. Fig. Fig. Fig. Fig. 28. ae PLATE 21 ANSERIFORMES AND PHOENICOPTERI All figures, except 28a and b, * 100 Anas platyrhynchos. Basal portion of barb from inner vane of primary. X 8. Portion of ventral part of basal region of barb, from outer vane of primary. X 120. Distal barbule from inner vane of remex. Proximal barbule from same. Distal barbule from outer vane of remex. Proximal barbule from same, distal third of barb. Distal barbule from outer vane of tail feather. Proximal barbule from same, distal third of barb. Distal barbule from outer vane of violet speculum feather. Nettion carolinense. Distal barbule from outer vane of primary. Distal barbule from outer vane of green speculum feather. Proximal barbule from same, distal third of barb. Mareca americana. Distal barbule from outer velvety black vane of scapular feather. Chauna cristata. Distal barbule from outer vane of remex. Proximal barbule from same. Phoenicopterus ruber. Distal barbule from inner vane of remex. Proximal barbule from outer vane of remex, distal third of barb. Proximal barbule from scapular feather, distal half of barb. [414] [CHANDLER] PLATE 21 13 UNIV. CALIF, PUBL. ZOOL. VOL. Fig. Fig. 33. a. PLATE 22 FALCONIFORMES All figures & 100 Gyps fulvus. Distal barbule from back feather. Proximal barbule from same. Distal barbule from outer vane of primary. Proximal barbule from same, distal third of barb. Gymnogyps californianus. Distal barbule from inner vane of remex. Same, with pennulum in lateral view. Proximal barbule from inner vane of remex. Distal barbule from outer vane of remex. Proximal barbule from same, distal third of barb. Gypogeranus serpentarius. Distal barbule from blue-gray scapular feather. Proximal barbule from same. Distal barbule from inner vane of remex. Proximal barbule from same. ; [416] [CHANDLER] PLATE 22 13 UNIV. CALIF, PUBL. ZOOL. VOL. OT i EOS ER Pie a a PTS Fig. Fig. Fig. Fig. Fig. Fig. 36. PLATE 23 FaLconrrorMeEs (Accipitres) All figures & 100 Falco peregrinus. Distal barbule from inner vane of remex. Proximal barbule from same. 4 Proximal barbule from outer vane of remex. Falco sparverius. Distal barbule from inner vane of remex. Buteo borealis. Distal barbule from inner vane of remex. Proximal barbule from same. Proximal barbule from outer vane of remex. Haliaeétus leucocephalus, Distal barbule from inner vane of remex. Proximal barbule from same. Polyborus cheriway. Distal barbule from inner vane of remex. Falco rusticola. Distal barbule from back feather. Proximal barbule from same. [418] [CHANDLER] PLATE 23 UNIV. CALIF. PUBL. ZOOL, VOL, 13 Se RR AERTS ER rn PLATE 24 GALLIFORMES All figures & 100 Fig. 42. Gallus domesticus. a. Distal barbule from inner vane of remex. b. Proximal barbule from same. ec. Distal barbule from outer vane of remex. d. Proximal barbule from same, about middle of length of barb. e. Proximal barbule from same, distal fourth of barb. f. Proximal barbule from back feather. g. Distal barbule from iridescent green tail plume. Fig. 48. Bonasa umbellus. a. Distal barbule from inner vane of remex. b. Proximal barbule from same. c. Proximal barbule from outer vane of remex. Fig. 44. Meleagris virginiana. a. Distal barbule from inner vane of remex. b. Proximal barbule from same. Fig. 45. Megapodius cumingi. a. Distal barbule from inner vane of remex. b. Proximal barbule from outer vane of remex, distal third of barb. Fig. 46. Penelope cristata. a. Distal barbule from inner vane of remex. Fig. 47. Lagopus lagopus. a. Distal barbule from white back feather. Fig. 48. Turnix lepurana. a. Distal barbule from inner vane of remex. b. Proximal barbule from same. [420] [CHANDLER] PLATE 24 13 UNIV, CALIF. PUBL, ZOOL. VOL. er oe Megere - nd itaied eds _— ; mp ao ge PLATE 25 CRYPTURIFORMES All figures & 135 Tinamus solitarius. Distal barbule from inner vane of remex. Portion of proximal barbule, from inner vane of remex. Distal barbule from outer vane of remex. Distal barbule from back feather, black. Portion of proximal vanule, from breast feather. Basal portion of down barbule, from back feather. [422] UNIV. CALIF, PUBL, ZOOL. VOL. 13 [CHANDLER] PLATE 25 Fig. 651. Hig. 52. PLATE 26 GRUIFORMES All figures & 100 Grus canadensis. Distal barbule from inner vane of remex. Distal barbule from outer vane of remex. Proximal barbule from same. Proximal barbule from back feathers. Distal barbule from breast feather, proximal half of barb. Barbule, distal or proximal, from breast feather, distal third of barb. Aramus giganteus. Distal barbule from back feather, proximal half of barb. Proximal barbule from same. Distal barbule from breast feather, about middle of barb. Proximal barbule from same, about middle of barb. Barbule, distal or proximal, from breast feather, distal third of barb. Rallus obsoletus. Distal barbule from inner vane of remex. Proximal barbule from same. Proximal barbule from outer vane of remex. Distal barbule from breast feather, about end of proximal third of barb. Distal barbule from same, about middle of barb. Distal barbule from same, distal third of barb. Proximal barbule from same, about end of proximal third of barb. Proximal barbule from same, distal third of barb. [424] [CHANDLER] PLATE 28 UNIV. CALIF. PUBL. ZOOL. VOL. 13 ace es a Fig. Fig. Fig. Fig. 53. a. 56. a. PLATE 27 GRUIFORMES, continued All figures & 100 Otis tarda. Distal barbule from inner vane of remex. Proximal barbule from same. Distal barbule from back feather. Proximal barbule from back feather. Psophia viridis. Distal barbule from inner vane of greater covert. Proximal barbule from outer vane of greater covert. Distal barbule from back feather. Proximal barbule from back feather. Barbule from iridescent green portion of outer vane of covert. Eurypyga helias. Distal barbule from inner vane of remex. Proximal barbule from same. Distal barbule from back feather. Proximal barbule from back feather. Cariama cristata. Distal barbule from back feather, near base of barb. Proximal barbule from same. [426] [CHANDLER] PLATE 27 UNIV. CALIF. PUBL. ZOOL. VOL. 13 Fig. Fig. Fig. Fig. Fig. Fig. Fig. PLATE 28 LARO-LIMICOLAE All figures * 100 Numenius americanus. Distal barbule from inner vane of remex. Proximal barbule from same. Distal barbule from outer vane of remex. Proximal barbule from same, distal fourth of barb. Distal barbule from back feather. Barbule, distal or proximal, from breast feather, distal half of barb. Parra spinosa. Distal barbule from back feather, near base of barb. Same, distal third of barb. Phalaropus fulicarius. Barbule from breast feather, distal third of barb. Cursorius gallicus. Distal barbule from inner vane of remex. Proximal barbule from same. Distal barbule from breast feather, near tip of barb. Larus occidentalis. Distal barbule from inner vane of remex. Proximal barbule from same. Distal barbule from outer vane of remex. Proximal barbule from same, distal fourth of barb. Barbule from breast feather, distal third of barb. Sterna maxima. Distal barb from outer vane of remex. Uria troille. Distal barbule from inner vane of remex. Proximal barbule from same. Distal barbule from outer vane of remex. Distal barbule from breast feather, near base of barb. Same, near tip of barb. Proximal barbule of same, near tip of barb. [428] [CHANDLER] PLATE 26 UNIVINCALIE. PUBL, ZOOL, VOL. 13 ae Shs asctstenan na, Fig. Fig. Fig. Fig. Fig. Fig. Fig. Fig. 64. 65. 66. PLATE 29 PTEROCLO-COLUMBAE All figures, except 67a, * 100 Columba livia. Distal barbule from inner vane of remex, white. Proximal barbule from same, white. Distal barbule from outer vane of remex, slate gray. Zenaidura macroura. Distal barbule from olive brown back feather. Melopelia asiatica. Distal barbule from blue-gray covert. Distal barbule from breast feather, pearl gray. Proximal barbule from same. Columba fasciata. Hooklet region of distal barbule from covert. 480. Barbule from iridescent green neck feather. Macropygia tenuirostris. Distal barbule from rufous under tail covert. Osmotreron vernans. Distal barbule from olive green covert. Goura coronata. Distal barbule from inner vane of remex, slate blue. Proximal barbule from same. Distal barbule from back feather, grayish blue. Proximal barbule from same. Barbule from loose barb of decomposed crest feather. Pteroclis arenarius. Distal barbule from inner vane of remex. Distal barbule from outer vane of scapular feather. Proximal barbule from same. [430] [CHANDLER] PLATE 29 13 UNIV. CALIF. PUBL. ZOOL. VOL. Fig. Fig. Fig. Fig. Fig. Fig. PLATE 30 CUCULIFORMES All figures & 125 Coccyzus americanus. Distal barbule from inner vane of remex. Proximal barbule from same. Distal barbule from outer vane of remex. Proximal barbule from same. Distal barbule from breast feather. Proximal barbule from same. Geococcyxz californianus. Proximal barbule from glossy green outer vane of remex. Cacatua galerita. Distal barbule from inner vane of remex. Proximal barbule from same. Distal barbule from same. Proximal barbule from same, distal third of barb. Melopsittacus sp. Distal barbule from outer vane of remex. Proximal barbule from same, distal third of barb. Tanygnathus lucionensis. Distal barbule from yellowish-olive-green back feather. Aprosinictus cyanopygius. Distal barbule from red belly feather. Proximal barbule from same. [482] [CHANDLER] PLATE 30 UNIV. CALIF, PUBL. ZOOL. VOL, 13 Fig. Fig. Fig. Fig. 78. PLATE 31 CorRACHIFORMES (Coraciae and Trogones) All figures & 100 Coracias affinis. Distal barbule from inner vane of remex. Proximal barbule from same. Proximal barbule from outer vane of remex. Ceryle alcyon. Proximal barbule from outer vane .of remex, distal half of barb, Proximal barbule from breast feather. Prionotelus temnurus. Distal barbule from inner vane of remex. Distal barbule from outer vane of remex. Proximal barbule from same, distal third of barb. Phaeromacrus resplendens. Barbule from brilliant green ornamental upper tail covert. Hydrocorax mindanensis. Distal barbule from inner vane of remex. Proximal barbule from same. Distal barbule from outer vane of remex. Same, with pennulum in lateral view. Proximal barbule from outer vane of remex, distal third of barb. Trrisor viridis. Distal barbule from inner vane of remex. Proximal barbule from outer vane of remex, distal third of far: [434] [CHANDLER] PLATE 81 ZOOL. VOL. UNIV. CALIF, PUBL. Fig. Fig. Fig. Fig. Fig. 84. PLATE 32 CoractiroRMES. (Striges, Caprimulgi, Cypseli) All figures, except 88b, c, and d, * 100 Bubo virginianus. Distal barbule from inner vane of primary. Proximal barbule from same. Proximal barbule from outer vane, on distal, recurved, tooth-like portion of barb. Aluco pratincola. Distal barbule from breast feather. Chordeiles virginianus. Distal barbule from outer vane of remex. Proximal barbule from same, distal third of barb. Podargus strigoides. Distal barbule from inner vane of remex. Proximal barbule from same. Selasphorus rufus. Distal barbule from outer vane of primary. Same, 275. Proximal barbule from outer vane of primary. 275. Proximal barbule from iridescent fiery-red gorget feather. 275. [436] [CHANDLER] PLATE 32 UNIV. CALIF, PUBL, ZOOL, VOL. 13 PLATE 33 Pict AND PASSERIFORMES All figures, except 95a, *K 125 Fig. 89. Melanerpes formicivorus. a. Distal barbule from inner vane of remex. b. Proximal barbule from same. c. Distal barbule from outer vane of remex. d. Proximal barbule from same, distal third of barb. Fig. 90. Rhamphastus ariel. a. Distal barbule from back feather. Fig. 91. Jacamerops grandis. a. Distal barbule from inner vane of remex. b. Distal barbule from outer vane of remex. c. Proximal barbule from same, distal third of barb. wo eS Cyanocitta stelleri. Distal barbule from inner vane of remex. Proximal barbule from same. Distal barbule from outer vane of remex. d. Proximal barbule from same. e. Distal barbule from breast feather. f. Proximal barbule from same. Fig. Fig. 98. Myiarchus cinerascens. a. Proximal barbule from outer vane of remex, distal half of barb. Fig. 94. Pipilo maculatus. a. Distal barbule from inner vane of remex. Fig. 95. Bombycilla garrula. a. Tip of covert feather, with “wax tip’. 7. [438] [CHANDLER] PLATE 83 UNIV. CALIF. PUBL. ZOOL. VOL. 13 PLATE 34 Types oF DowN BARBULES Entire barbules drawn 40; portions of barbules marked in parenthesis drawn enlarged, * 285. Fig. Fig. Fig. Fig. 96. Spheniscus mendiculatus. Entire barbule. 6b. same, enlarged. Puffinus griseus. Entire barbule. 0b. basal portion. c. terminal portion. Sula variegata. Entire barbule. 0b. same, enlarged. Plotus anhinga. Entire barbule. 0b. basal portion. c. terminal portion. Botaurus lentiginosus. Entire barbule. 0b. basal portion. c. terminal portion. [440] [CHANDLER] PLATE 34 UNIV. CALIF. PUBL, ZOOL. VOL. 183 Entire barbules drawn PLATE 35 Types oF Down BARBULES, continued drawn enlarged, * 285. Fig. 101. Guara rubra. Entire barbule. 0b. basal portion. Phoenicopterus ruber. Entire barbule. b. basal portion. Olor columbianus. Entire barbule. b. basal portion. Mergus americanus. Entire barbule. b. basal portion. Falco sparverius. Entire barbule. 6. basal portion. portion. [442] 40; portions of barbules marked in parenthesis c. terminal portion. c. terminal portion. ec. terminal portion. ec. distal portion. c. middle portion. d. terminal [CHANDLER] PLATE 35 UNIV, CALIF, PUBL. ZOOL. VOL. 183 PLATE 36 TYPES OF DowN BARBULES, continued Entire barbules drawn 40; portions of barbules marked by parenthesis drawn enlarged, * 285. Fig. 106. a. Fig. 107. a. Fig. 108. da. db. Fig. 109. a. b. ELurypyga helias. Entire barbule. 6. basal portion. c. terminal portion. Rallus obsoletus, Entire barbule. b. basal portion. c. terminal portion. Meleagris virginiana. Entire barbule from distal vanule near base of barb. Basal portion. c. middle portion. d. terminal portion. Zenaidura macroura. Entire barbule from near base of barb. Basal portion. c. middle portion. d. terminal portion. [444] [CHANDLER] PLATE 36 UNIV. CALIF, PUBL, ZOOL. VOL. 13 PLATE 37 TYPES OF DOWN BARBULES, continued Entire barbules drawn 40; portions of barbules marked by parenthesis drawn enlarged, 285. Fig. 110. Fig. 111. Fig. 112. Fig. 113. Fig. 114. Fig. 115. Momotus lessoni. Entire barbule. 6. basal portion. c. terminal portion. Hydrocorax mindanensis. Entire barbule. 0b. basal portion. c. terminal portion. Eugenes fulgens. Entire barbule from near base of barb. Basal portion. ec. distal portion. Rhamphastus ariel. Entire barbule from near base of barb. Basal portion. c. terminal portion. Pipilo maculatus. Entire barbule from near base of basal barb. Basal portion. c. terminal portion. Corvus corax. Entire barbule from near base of basal barb. Basal portion. [446] [CHANDLER] PLATE 37 13 UNIV. CALIF, PUBL. ZOOL. VOL. ~ - UNIVERSITY OF CALIFORNIA PUBLICATIONS— (Continued) ZOOLOGY, Vol. 18. Vol. 14. Vol. 15. Vol. 16. Vol, 12 (Continued) 13. Report upon Mammals and Birds found in Portions of Trinity, Siskiyou and Shasta Counties, California, by Louise Kellogg. Pp. 835-398, plates 15-18. 14. An Analysis of the Vertebrate Fauna of the Trinity Region of Northern California, by Joseph Grinnell. Pp. 399-410. Nos. 138 and 14in one cover. January, 1916-..022.2..2..-..t.ceeeeeeeeee 1. The Schizopoda.of the San Diego Region, by Calvin O. Esterly. Ppi1-20; plates: 1-25 April, TON so a cappmonncenductian 2.-A Study of the Occurrence and Manner of Distribution of the Ctenophora of the San Diego Region, by Calvin O. Esterly. Pp. 5 te ee vg bs Rk enn Pen ncn ae MP eee ARN a 3. A New Self-Regulating Paraffin Bath, by C. W. Woodworth. Pp. 39-42, 2 text figures. April, 1914 22... icicle sekeectdeeececteeetneee 4, Diplodinium ecaudatum, with an Account of Its Neuromotor Ap- paratus, by Robert G. Sharp. Pp. 43-122, plates 3-7, 4 text figures. 0% EMG he Bo Se ae Reel os line kd US SS RN rile Ua Sains ht aco ae aa a 5. The Vertical Distribution and Movements of the Schizopoda of the San Diego Region, by Calvin O. Esterly. Pp. 123-145. May, 1914 6, The Anatomy of Heterodontus francisci. I. The Exoskeleton, by J. Frank Daniel. Pp. 147-166, plates 8-9, 4 text figures. May 23, £1 rE Ci SAA AE MC RY erent EOL SO SM SRR EAA CEO CMs — ope REAL Le 7. The Movements and Reactions of the Isolated Melanophores of the Frog, by S..J. Holmes. Pp. 167-174, plate 10, August, 1914.......... 8. Polychaetous Annelids of the Pacific Coast in the Collections of the Zoological Museum of the University of California, by Aaron L. Treadwell. Pp. 175-234, plates 11-12. 9. New Syllidae from San Francisco Bay (collected by the U. 8S. 8. ‘* Albatross’’), by Aaron L. Treadwell. Pp. 235-238, 7 text figures. Nos. 8 and 9 in one cover. October, 19140200 ...022. coe eels leee eee 10. Note on the Medusan Genus Stomolophus, from San Diego, by Henry B. Bigelow. Pp. 239-241. September, 1914.--.........022....-... 11. A Study of the Structure of Feathers, with Reference to Their Taxonomic Significance, by Asa O. Chandler. Pp. 243-446, plates sD sy ree = 1) oy a Rens Gs Relat re ne 3 Cen ea IR) UMN Nae len ket NOE Soe PAM 12. Anatomical Adaptations in the Thoracic Limb of the California Pocket Gopher and Other Rodents, by Charles Daniel Holliger. Pp. 447-494, plates 38-39, 20 text figures. March, 1916-.......22022.20..... 1, A Report upon the Physical Conditions in San Francisco Bay, Based upon the Operations of the United States Fisheries Steamer ‘‘ Al- batross’’ during the Years 1912 and 1913, by F. B. Sumner, G. D. Louderback, W. L. Schmitt, and E, C. Johnston... Pp. 1-198, plates 1-13; 20 text figures. July, 1914.20.22. cece csceeceedeeene 1. Hydrographic, Plankton, and Dredging Records of the Scripps In- stitution for Biological Research of the University of California, 1901 to 1912, compiled and arranged under the supervision of W. E. Ritter by Ellis L. Michael and George F. McEwen. Pp. 1-206, 4 text figures and map. July, 1915 .-.2.2)i2.ccccccee eee nce ese 1. An Outline of the Morphology and Life-History of Crithidia lepto- coridis, sp. noy., by Irene McCulloch. Pp. 1-22, plates 1-4, 1 text figure; Seéptemper, VOli i220. ee eS ee oe Se 2,.0n Giardia microti sp. nov., from the Meadow Mouse, by Charles Atwood Kofoid and Elizabeth Bohn Christiansen. Pp. 23-29, 1 figure in text. $. On Binary and Multiple Fission in Giardia muris (Grassi), by Charles Atwood Kofoid and Elizabeth Bohn Christiansen. Pp. 30-54, plates 5-8, 1 figure in text. Nos. 2 and 3 in one cover. November, 1915-22222. 4. The Cultivation of Tissues from Amphibians, by John C. Johnson. Pp. 55-62, 2 figures in text. November, 1916.22.02... ccc cececesceeeeeeeee 5. Notes on Tintinnoina. 1. On the Probable Origin of Dictyocysta tiara Haeckel. 2. On Petalotricha entzi sp. nov., by Charles Atwood Kofoid. Pp. 63-69, 8 figures in text. December, 1915..... «75 15 15 05 -80 .20 -20 10 2.00 45 2.25 30 -10 05 oie UNIVERSITY OF CALIFORNIA PUBLICATIONS— (Continued). “ZOOLOGY, Vol. 16 (Continued) ~ S 6. Binary and Multiple Fission in H ribeailties, by Olive Swezy. Pp. 71- 88, plates 9-11. 7. On a New Trichomonad Flagellate, Trichomitus parvus, from the Intestine of Amphibians, by Olive Swezy. Pp. 89-94, plate 12. Nos. 6 and 7 in one cover. December, 1915.2... cee ceceeceee 8. On Blepharocorys equi sp. nov., a New Ciliate from the Caecum of the Horse, by Irwin C. Schumacher. Pp. 95-106, plate 18. De- COMBO; -LOUG eae ee e O a oe Ti oos ae 9, Three New Helices from California, by: 8. tillman Berry. Pp. 107- STD aM aTY LSE Bo ee A oa apc ae ae a nee, : 10. On Trypanosoma tridtomae, a New Flagellate from’ a Hemipteran Bug from the Nests of the Wood Rat Neotoma fuscipes, by Charles Atwood Kofoid and Irene. McCulloch. Pp. 113-126, plates 14-1565 > February, 1916 os se ek SN a ee 11. The Genera: Monocercomonas and Polymastiz, by Olive Swezy. Pp. 127-138, plates 16-17. February, 1916....c0.2..c..22. cee peeeett eee eesee cate 12. Notes on the Spiny Lobster (Panulirus interruptus) of the Cali- fornia Coast, by Bennet M. Allen. Pp. 139-152. March, 1916....... 18. Notes on Marine Fishes of California, by Carl L. Hubbs. Pp. 153— 169, plates “18-20; — Waren, LOLG ook acca eg cee bg esaapeoesasaneneeee 14. The Feeding, Habits and Food of Pelagic Copepods and the Ques- tion of Nutrition by Organic Substances in Solution in the Water, by Calvin O. Esterly. Pp. 171-184. 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