UNIVERSITY Of « 5HSUKSU M BIOLOGY If (7. Variation in Scales in Dermophis mexicanus (Amphibia: Gymnophiona): Are Scales of Systematic Utility? Marvalee H. Wake Kristen M. Nygren A Contribution in Celebration of the Distinguished Scholarship of Robert F. Inger on the Occasion of His Sixty-Fifth Birthday fc 5T <*fc % %y h. September 30, 1987 Publication 1378 4 PUBLISHED BY FIELD MUSEUM OF NATURAL HISTORY Information for Contributors to Fieldiana General: Fieldiana is primarily a journal for Field Museum staff members and research associates although manuscripts from nonaft.liated authors may be considered as space permits. The Journal carries a page charge of $65 per printed page or fraction thereof. Contributions from staff, research associates, and invited authors will be con- sidered for pub .cation regardless of ability to pay page charges, but the full charge is mandatory for nonaffiliated authors of unsolicited manuscripts. Payment of at least 50% of page charges qualifies a paper for expedited process- ing, which reduces the publication time. Manuscripts should be submitted to Dr. Timothy Plowman, Scientific Editor, Fieldiana, Field Museum of Natural H,sK>ry Chicago, Illinois 60605-2496. USA. Three complete copies of the text (including title page and abstract) and oi the illustrations should be submitted (one original copy plus two review copies which may be machine copies) No manuscripts will be considered for publication or submitted to reviewers before all materials are complete and in the hands or the Scientific Editor. Text: Manuscripts must be typewritten double-spaced on standard-weight, 8'/,- by 11-inch paper with wide margins on all four sides . For papers longer than 100 manuscript pages, authors are requested to submit a "Table of Contents " a List of Illustrations," and a "List of Tables." In most cases, the text should be preceded by an "Abstract" and should conclude with Acknowledgments" (if any) and "Literature Cited." All measurements should be in the metric system The format and style of headings should follow those of recent issues of Fieldiana. For more detailed style informa- tion, see The Chicago Manual of Style (13th ed.), published by The University of Chicago Press, and also recent issues ot rieldiana. In "Literature Cited." authors are encouraged to give journal and book titles in full. Where abbreviations are desirable (e.g., ,n citation of synonymies), authors consistently should follow Botanico-Periodicum-Huntianum and l^Tteonomtc^ Biosis Data Base (1983) published by the BioSciences Information Service. References should be typed in the following form: Croat. T. B. 1978. Flora of Barro Colorado Island. Stanford University Press. Stanford, Calif 943 pp Grubb P j. J. R. Lloyd. andT. D. Punnington 1963. A comparison of montane and lowland rain fores, in Ecuador I The forest structure, physiognomy, and floristics. Journal of Ecology, 51: 567-601. ctuaaor. i. ine Langdon. E. J. M. 1979. Yage among the S.ona: Cultural patterns in visions, pp. 63-80. In Browman, D L and R A Schwarz, eds.. Spirits, Shamans, and Stars. Mouton Publishers, The Hague, Netherlands MvT; JTl!4AnJhe rS,°rC tribCS o ? Uad0r' PP- 785~821- '" S,eward- J' H" ed - Hand1*^ °f South American Indians Vol. 2. The Andean C.vihzations. Bulletin 143. Bureau of American Ethnology. Smithsonian Institution. Washington DC STOLZE, R. G. 1981. Ferns and fern allies of Guatemala. Part II. Polypodiaceae. Fieldiana: Botany, n.s.. 6: 1-522. Illustrations: Illustrations are referred to in the text as "figures" (not as "plates"). Figures must be accompanied by some md.cat.on of scale, normally a reference bar. Statements in figure captions alone, such as " x 0 8 " are not acceptable. Capt.ons should be typed double-spaced and consecutively. See recent issues oi Fieldiana for details of Figures as submitted should, whenever practicable, be 8'/2 by 11 inches (22 x 28 cm) and may not exceed H'/2 by 16 A inches (30 x 42 cm). Illustrations should be mounted on boards in the arrangement you wish to obtain in the printed work. This original set should be suitable for transmission to the printer as follows: Pen and ink drawings may be originals (preferred) or photostats; shaded drawings should be originals, but within the size limitation; and photo- stats should be high-quality, glossy, black and white prints. All illustrations should be marked on the reverse with author s name, figure number(s), and "top." Original illustrations will be returned to the author upon publication unless otherwise specified. Authors who wish to publish figures that require costly special paper or color reproduction must make prior arrangements with the Scientific Editor. Page Proofs: Fieldiana employs a two-step correction system. Each author will normally receive a copy of the edited manuscript on which deletions, additions, and changes can be made and queries answered. Only one set of page proofs w.ll be sent. All desired corrections of type must be made on the single set of page proofs. Changes in page proofs (as opposed to corrections) are very expensive. Author-generated changes in page proofs can only be made if the author agrees in advance to pay for them . FIELDIANA Zoology NEW SERIES, NO. 36 Variation in Scales in Dermophis mexicanus (Amphibia: Gymnophiona): Are Scales of Systematic Utility? Marvalee H. Wake Kristen M. Nygren Department of Zoology Department of Zoology Museum of Vertebrate Zoology Museum of Vertebrate Zoology University of California University of California Berkeley, California 94720 Berkeley, California 94720 A Contribution in Celebration of the Distinguished Scholarship of Robert F. Inger on the Occasion of His Sixty-Fifth Birthday Accepted for publication November 21, 1986 September 30, 1987 Publication 1378 PUBLISHED BY FIELD MUSEUM OF NATURAL HISTORY © 1987 Field Museum of Natural History ISSN 0015-0754 PRINTED IN THE UNITED STATES OF AMERICA Table of Contents Abstract Introduction Materials and Methods Results . Scale Number, Size, and Shape ^ Ontogenetic Variation Sexual Dimorphism Scale Structure Discussion Acknowledgments Literature Cited 2. Large scales from primary annular scale array shown in Figure 1 4 3. Scanning electron micrographs of scale of Dermophis mexicanus 6 List of Tables 1. Specimens of Dermophis mexicanus ex- amined for scale morphology 2 2. Numbers of scales in annuli of Dermo- phis mexicanus 5 3. Sizes of scales in annuli of Dermophis mexicanus specimen C 5 List of Illustrations 1. Scales from primary annuli of a 355-mm female Dermophis mexicanus in Variation in Scales in Dermophis mexicanus (Amphibia: Gymnophiona): Are Scales of Systematic Utility? Abstract Several workers have suggested that the size, shape, and number of dermal scales in gymno- phiones may be of use in identifying taxa. How- ever, an examination of scale morphology within and among individuals, let alone among species, has not been documented. Our data indicate that there are within- and among-individual differ- ences, including ontogenetic variation and sexual dimorphism. We conclude that scales cannot be used as taxonomic characters unless samples are large enough to be tested statistically. Since few species are likely to be sampled adequately, the statistical comparison criterion cannot be used comparatively. Further, excision and preparation of large numbers of scales is somewhat destructive of specimens and inordinately time-consuming. We do not consider scale morphology a useful character for identification of taxa. The biology of scales remains a most provocative problem. Introduction The origins, homologies, and conformation of the dermal scales of gymnophiones have attracted the attention of biologists since their initial de- scription by Mayer (1829a,b). Rathke (1852) and Leydig (1853) commented on the presence of scales; Wiedersheim (1879) and Sarasin and Sarasin (1887-1890) carefully described them. Cockerell (1911, 1912), Phisalix (1910, 1912), Datz (1923), Peyer (1931), Ochotorena (1932), and Marcus (1934) described scales, often in conjunction with consideration of skin glands. More recently Feuer (1962), Gabe (1971), Taylor (1972), Wake (1975), Casey and Lawson (1979), Perret (1982), Fox (1983), and especially Zylberberg et al. (1980) have looked carefully at the structure of gymnophione scales. Zylberberg et al. (1980) present excellent evidence for the homology of gymnophione and teleost scales, and controvert Feuer's (1962) sug- gestion that the squamulae on scales are arranged in growth series. Werner (1931) suggested that there are generic-level differences in scale morphology, and Taylor (1968, 1969, 1972) suggested that there also are species-level differences. Zylberberg et al. (1980) state that Taylor's work demonstrates the utility of scales in classifying gymnophiones (cae- cilians), though they also comment on the marked similarity of the two species that they studied. However, there has been no thorough assess- ment of variation in scale morphology, number, and distribution within individuals and within populations, let alone comparing variation in species, though "variation" has been noted (Feuer, 1962; Taylor, 1972; Zylberberg et al., 1980). Tay- lor controlled for variation to some degree, as did Feuer, by examining only the largest scales from the terminal primary annulus, but they did not compare even several large scales from an indi- vidual to assess variation. Taylor also considered the number of scale rows present to be potentially useful as a character, but he did not examine on- togenetic series. It seems requisite to understand how much vari- ation occurs among scales in individuals and with- in populations before one can select scales and compare them among species. We examined spec- imens from a Guatemalan population of Dermo- phis mexicanus in order to make a preliminary assessment of variation in scales. We considered scale size, shape, and number within and among annuli of an individual, and among individuals of both sexes and of comparable and different sizes (and, presumably, ages). While collaborating with WAKE & NYGREN: DERMOPHIS MEXICANUS SCALES Dr. Louise Zylberberg on studies of scale ontogeny and scale microstructure in Dermophis mexicanus, we here report preliminary information about adult scale structure and present information on scale variation that indicates that (1) one must consider multiple scales in multiple annuli, preferably from several individuals, in order to determine whether their morphology and distribution characterize species; (2) there is ontogenetic variation in scale size and number; and (3) variation is such that the taxonomic utility of scales is minimal to non- existent. Materials and Methods Scales were extracted from the annuli of five Dermophis mexicanus from San Marcos, Guate- mala (see table 1 for specimen data). All scales from dorsal to ventral midlines on the left side of the first primary annulus containing scales, the first and fifth secondaries containing scales, every 1 Oth succeeding annulus in both series, and the terminal annuli in the series were extracted and counted for all five specimens (see table 2). Numbers of rows of scales were counted before the scales were ex- tracted. Scales from the right sides of the respective annuli of three specimens (A, C, and E) were ex- tracted, placed on slides, stained with alizarin red-S solution, air-dried, and coverslipped. Scales were then measured and photographed. Pieces of skin including several annuli were taken from var- ious regions of the body of a female specimen 335 mm in total length (TL). Segments were sagittally sectioned, serially mounted, and stained with hematoxylin-eosin, Heidenhain's azan, or picro- ponceau. Variation in size, structure, and orien- tation therefore was observable at higher resolu- tion than in the gross preparations. Additional scales were mounted on stubs, sputter-coated with Table 1. Specimens of Dermophis mexicanus ex- amined for scale morphology. Total No. of No. of Speci- length primary secondary men (mm) annuli annuli Sex A 386 108 67 <5 B 385 103 75 9 C 377 100 61 9 D 260 106 66 9 E 255 101 66 <5 gold-palladium alloy, and examined and photo- graphed with an ISI-DS-130 dual-stage scanning electron microscope. Results Scale Number, Size, and Shape Scales first occur in approximately the 1 Oth pri- mary annulus in large adults and the 20th to 30th of small adults. Most anterior annuli are very shal- low. Annular depth first increases laterally, and scales lie in the deeper regions of the annuli of four of the five specimens examined. Scales are small (see table 3) and irregularly shaped (figs. 1A, 2 A). Following the 30th annulus, scale number in- creases steadily. Scales are distributed both more dorsally and more ventrally in increasingly pos- terior annuli. Scales are distributed in a single overlapping row. Between primary annuli 30 and 50, both scale number and size increase greatly. Scales occur throughout each annulus, except mid- ventrally, and are arrayed in two rows of variably overlapping scales. One row appears to be associated with the anterior wall of the opened annulus, the other with the posterior wall. Dorsomedial scales are not at- tached to either wall. Following the 50th primary annulus, the number of scales and their distribu- tion is fairly constant (see table 2). Most of the scales are larger (see table 3) than those occurring more anteriorly, though some very small scales also occur in each annulus (fig. 1D-F, table 3). Small scales are distributed throughout the annuli, interspersed among the larger ones. The shapes of the scales show considerable variation regardless of size (figs. 1-2). Secondary annuli consistently contain scales, except for the anteriormost small shallow lateral one or two. Scale number per annulus increases more rapidly in secondaries than in primaries. The number is relatively stable by the 20th to 30th secondary annulus. The pattern of increase in scale size and distribution is similar to that described above for primary annuli, and scale shapes are similarly variable. The numbers of scales in sec- ondary annuli are slightly fewer than in the pri- mary annuli with which they are associated. There are few differences in counts among specimens B- E, but specimen A, the large male, has more than twice as many scales in primary annuli than in secondaries. A comparison of our photographs of scales from within a single annulus of a Dermophis FIELDIANA: ZOOLOGY Fig. 1. Scales from primary annuli of a 377-mm (total length) female Dermophis mexicanus. A comparison of these photographs shows the size and shape variation of scales within and among annuli. All scales photographed to same scale; bar = 2.0 mm. A, Scales from 30th primary annulus behind head; B, scales from 40th annulus; C, scales from 50th annulus; D, scales from 60th annulus; E, scales from 80th annulus; F, scales from 90th annulus. mexicanus with the photographs of the scales of a great number of species of caecilians presented by Taylor (1972) shows that all of the diversity among most species, regardless of genus or even family, is equally present within an annulus of an individual, at least of D. mexicanus. Ontogenetic Variation Ontogenetic variation in scale numbers is sug- gested by our data. Specimens D and E are a re- cently matured male and female, respectively, WAKE & NYGREN: DERMOPHIS MEXICANUS SCALES Fig. 2. Large scales from primary annular scale array shown in Figure 1. Note conformation and variation. All photographed to same scale; bar = 0.5 mm. A, Scale from 30th annulus; B, scale from 40th annulus; C, scales from 50th annulus; D, scale from 60th annulus; E, scale from 80th annulus; F, scale from 90th annulus. FIELDIANA: ZOOLOGY Table 2. Numbers of scales in annuli of Dermophis mexicanus. Scales were extracted from the dorsal midline to the venter of the left side of each specimen. Speci- Primary annulus number men 1 5 10 20 30 40 50 60 70 80 90 100 A 0 0 33 93 112 134 150 151 150 167 168 142 B 0 0 0 27 59 60 80 95 99 90 92 80 C 0 0 6 14 54 90 106 115 102 98 95 81 D 0 0 0 0 0 6 14 25 36 42 52 51 E 0 0 0 0 20 37 45 51 52 50 57 24 Secondary annulus number 1 5 10 20 30 40 50 60 70 A* 2 0 11 64 114 117 126 141 39 B* 1 23 30 73 70 88 75 86 90 C 3 13 50 85 114 112 115 85 D* 1 3 5 27 29 37 43 51 8 E* 1 4 11 41 47 55 54 62 10 Secondary annulus numbers are positioned to show their association with primary annuli; i.e., the first secondary occurs at approximately the 20th primary in an anterior-to-posterior series. Specimen designations A-E refer to specimens in Table 1 . * Terminal secondary annulus for A is 67; B, 75; D, 66; E, 66. Numbers of scales in terminal annuli for A, C, D, and E are indicated; number for B is 18. probably three years old (Wake, 1980). They have roughly half the number of scales per annulus of comparable primaries and secondaries of larger specimens (see table 2) that are perhaps six years old (Wake, 1980). Scale distribution is similar to that in the larger specimens. These data indicate that scales may be added throughout life, and that they may be perennial, as in teleosts. The data further suggest that scale development within the pocket of an annulus is not synchronous, so Feuer's (1962) ideas about the concentric rings on annuli as indicators of age are questionable on grounds other than those mentioned by Zylberberg et al. ( 1 980). An appropriate sample is necessary to cor- roborate these suggestions. Our measurements indicate that scales in the smaller specimens are also smaller. The largest scales found in specimen E are approximately two- thirds the size of the largest scales in specimen A (1.1 x 0.9 mm vs. 1.6 x 1.6 mm); means of scale measurements from terminal primary annuli are 0.66 x 0.66 mm for E, 0.92 x 0.82 mm for A. Since we have no information on scale growth, two hypotheses about the increase of scale size with age must be tested. Either scales do grow throughout life, perhaps by the addition of con- centric squamulae to a growing base plate (as sug- gested by Feuer, 1962, but partially refuted by Zylberberg et al., 1 980), or the scales that are added later in life, as indicated by the increase in numbers in larger specimens, achieve larger size during a Table 3. Sizes of scales (mm) in annuli of Dermophis mexicanus specimen C. x of dimensions (height X width) Annulus of 10 scales per number annulus Range Primary 20 0.65 X 0.40 0.6 X 0.4-0.7 x 0.4 30 0.68 X 0.36 0.4 X 0.3-1.2 x 0.6 40 0.65 X 0.43 0.4 X 0.3-0.9 x 0.5 50 0.93 X 0.48 0.4 X 0.3-1.5 x 0.7 60 1.16 X 0.89 0.8 X 0.6-1.4 x 1.1 70 1.14 X 0.83 0.7 X 0.3-1.4 x 1.0 80 1.18 X 0.92 0.6 X 0.4-1.5 x 1.3 90 1.40 X 1.09 0.9 X 0.6-1.7 x 1.7 Secondary 1 0.70 X 0.40 0.5 X 0.4-0.8 x 0.4 10 0.76 X 0.42 0.4 X 0.3-1.1 x 0.5 20 0.81 X 0.64 0.6 X 0.5-1.2 x 0.8 30 0.93 X 0.73 0.5 X 0.4-1.4 x 1.0 40 1.20 X 1.10 0.9 X 0.8-1.4 x 1.3 50 1.26 X 0.93 0.5 X 0.4-1.6 x 1.3 60 1.39 X 1.25 0.6 X 0.6-1.7 x 1.6 short growth period, resulting in diverse sizes of scales within each annulus. Sexual Dimorphism Male specimens of both size classes examined have greater numbers of scales in comparable an- WAKE & NYGREN: DERMOPHIS MEXICANUS SCALES Fig. 3. Scanning electron micrographs of scale of Dermophis mexicanus. A, Whole scale with mineralized denticles on surface. Area in rectangle shown in B. Bar = 1 .0 mm. B, Close-up of surface denticles. Note complex folding patterns. Bar = 200 nm. C, Further magnification of denticles to demonstrate granular spherules of mineralized material. Bar = 10 nm. nuli than do females of approximately the same sizes within the classes (see table 2). Consequently the total number of scales is greater in males of both sizes than in comparable females. As noted above, the larger male (A) has approximately twice the number of scales in primary annuli than have the females of comparable size that were sampled, though the difference in numbers of scales in sec- ondaries differs little. Male A also has scales dis- tributed throughout its anterior annuli, rather than just laterally as in the females. Again, the number of specimens examined does not allow a firm con- FIELDIANA: ZOOLOGY """*»»»**mffl mnimnmiBiiilMMi elusion, but the greater number of scales in males of both sizes suggests that males may have more scales than females. Scale Structure The scales of Dermophis mexicanus are com- posed of an unmineralized bilaminar fibrous base plate topped with mineralized squamulae (fig. 3). The squamulae are irregularly shaped but basically elongate rhomboids, especially toward the periph- ery of the scales. Squamulae are less elongate in the center regions of scales. They are arrayed in concentric series and are similar to those of several other species, as shown by Taylor (1972) and Zyl- berberg et al. (1980). The pattern of the surface structure with many small mineralized spherules (fig. 3C) is similar to that reported by Zylberberg et al. ( 1 980) in both Ichthyophis and Hypogeophis. In sagittal section, several scales are apparent in the scale pocket. This is due to the overlapping of scales in each of the two major rows (see above). Because of the curvature of the scales, differences in the thickness and arrangement of both the base plate and the squamulae are shown. This is a con- sequence of the normal variation in these struc- tures across the diameter of any scale. Discussion There is considerable variation in scale size, shape, and number within annuli and among in- dividuals from a single population of Dermophis mexicanus. Some of that variation may be cor- related with size (or age) and with sex. Controlling for variation by restricting comparison to the larg- est scale from the terminal annulus, as Taylor (1972) did, does not consider the problem of on- togenetic variation, which our data suggest is sub- stantial, and does not deal with the possibility of sexual differences, which our data also indicate. As noted above, the variation of scale character- istics within an annulus of a single individual is comparable to the variation Taylor (1972) at- tempted to show among taxa. We therefore con- clude that scale size, shape, and number are not reliable indicators of species (or higher taxonomic category) identity. This does not preclude the likelihood that large samples of scales that can be treated statistically might indicate differences. This would require that any ontogenetic and sexual variation be accounted for, as well as that within and among annuli of individuals. It is not unreasonable that different species would have different numbers of scales among comparable annuli of similarly sized ani- mals, and that scale size means and ranges might differ. However, we do not have statistically ap- propriate data for other species to compare to data for Dermophis mexicanus. Taylor (1 972) suggested that the numbers of rows of scales within annuli might be a useful character. Our data suggest that rows as well as numbers of scales might increase during growth. We also see variation in the number of rows in anterior annuli relative to more posterior ones. However, the in- crease from one row to two in Dermophis mexi- canus is not comparable to that of species that may have as many as eight rows of scales in some annuli. Our preliminary survey of such species indicates that there is anteroposterior variation in numbers of rows among annuli. We do not have any information on ontogenetic variation in these species. More crucially, we are not convinced that the acquisition of such data is necessarily appropriate. Excision of scales from multiple annuli of multiple specimens is somewhat destructive to the speci- mens. Maintaining, mounting, counting, and mea- suring the scales is not time-efficient if there are any more reliable indicators for identification. Most species of caecilians are represented by only a few specimens, and very rarely by ontogenetic or pop- ulation series; therefore, the statistical comparison criterion cannot be utilized throughout a clade. It remains possible, indeed likely, that there are dif- ferences in the microstructure of scales among taxa. However, the developmental and physiological data necessary to corroborate this supposition are not yet available, and it is likely that only a few species can be subject to such analysis in the near future. The search for systematic characters should include consideration of the utility and general applicability of the characters in question. Acknowledgments We thank Addye Brown and Wendy Marlor for preparing material, and Ted Papenfuss, Robert Seib, David Wake, and Tom Wake for collecting specimens. We appreciate the assistance of the Electron Microscope Laboratory of the University of California, Berkeley, in preparing the scales for WAKE & NYGREN: DERMOPHIS MEXICANUS SCALES scanning electron microscopy. We are especially grateful to the National Science Foundation, which has supported the work of the senior author on the biology of caecilians. It is a particular pleasure to acknowledge the many contributions of Robert F. Inger to the un- derstanding of the biology of tropical amphibians, including caecilians, and to herpetology in general. His generosity, delight in discussion, and percep- tions of biology, science, and people have im- proved the work of many of us. Literature Cited Casey, J., and R. Lawson. 1979. Amphibians with scales: The structure of the scale in the caecilian Hy- pogeophis rostratus. British Journal of Herpetology, 5: 831-833. Cockerell, T. D. A. 1911. Additional note on retic- ulated fish-scales. Science, 34: 126-127. . 1912. The scales of Dermophis. Science, 36: 681. Datz, E. 1923. Die Haut von Ichthyophis glutinosus. Jena Zeitschrift fur Naturwissenschaft, 59: 31 1-342. Feuer, R. C. 1962. Structure of scales in a caecilian {Gymnopis mexicanus) and their use in age determi- nation. Copeia, 1962: 636-637. Fox, H. 1983. The skin of Ichthyophis (Amphibia: Caecilia): An ultrastructural study. Journal of Zool- ogy, London, 199: 223-248. Gabe, M. 1971. Donnees histologiques sur le tegument d' Ichthyophis glutinosus L. (Batracien, Gymno- phione). Annales des Sciences Naturelles, Zoologie, Paris, 12eme serie, 13: 573-608. Leydig, F. 1853. Anatomisch-histologische Unter- suchungen iiber Fische und Reptilien. G. Riemer, Ber- lin. Marcus, H. 1934. Beitrag zur Kenntnis der Gymno- phionen. XXI. Das Integument. Zeitschrift fur Ana- tomische Entwicklungsgeschichte, 103: 189-234. Mayer, A. F. T. C. 1829a. Uber die Schuppen der Caecilian. Isis, 21: 694. . 1 829b. Fernerer Untersuchungen iiber die hin- ter Extramitat der Ophidier und iiber die Schuppen der Caecilia. Zeitschrift fur Physiologie herausgegeben von Tiedemann und Treviranus, 1889: 1-3. Ochotorena, I. 1932. Nota acerca la histologic de la piel de Dermophis mexicanus Dumeril y Bibron. An- ales del Instituto Biologia de Mexico, 3: 363-370. Perret, J. 1982. Les ecailles de deux Gymnophiones africains (Batraciens apodes), observees au micro- scope electronique a balayage. Bonner zoologische Beitrag, 33: 343-347. Peyer, B. 1931. Hartgebilde des Integumentes, pp. 703- 752. In Bolk, L., E. Goppert, E. Kallius, and W. Lu- bosch, eds., Handbuch der vergleichenden Anatomie des Wirbeltiere, vol. 1. Urban and Schwarzenberg, Berlin. Phisalix, M. 1910. Repartition et specificite des glandes cutanees chez les Batraciens. Annales des Sciences Na- turelles, Zoologie, Paris, 12: 183-201. . 1912. Repartition des glandes cutanees et leur localisation progressive en fonction de la disparition des ecailles chez les Batraciens Apodes. Verhandlung- en der VIII internationalen Zoologen-Kongresses. G. Fischer, Jena, 1912: 605-609. Rathke, H. 1852. Bemerkungen iiber mehrere Kor- pertheile der Coecilia annulata. Muller's Archiv fur Anatomie und Physiologie, 1852: 334-360. Sarasin, P., and F. Sarasin. 1887-1890. Ergebnisse naturwissenschaftlicher Forschungen auf Ceylon. II. Zur Entwichlungsgeschichte und Anatomie des cey- lonischen Blindwuhle Ichthyophis glutinosus. L. C. W. Kriedels Verlag, Wiesbaden. Taylor, E. H. 1968. Caecilians of the World. A Taxo- nomic Review. University of Kansas Press, Lawrence. . 1 969. A new family of African Gymnophiona. University of Kansas Science Bulletin, 48: 297-305. 1972. Squamation in caecilians, with an atlas of scales. University of Kansas Science Bulletin, 59: 989-1164. Wake, M. H. 1975. Another scaled caecilian (Gym- nophiona: Typhlonectidae). Herpetologica, 31: 134— 136. 1980. Reproduction, growth, and population structure of the central American caecilian Dermophis mexicanus. Herpetologica, 36: 244-256. Werner, F. 1931. Ordnung der Amphibia, Apoda. Ku- kenthals Handbuch der Zoologie, 6: 143-208. Wiedersheim, R. 1879. Die Anatomie der Gymno- phionen. Gustav Fischer Verlag, Jena. Zylberberg, L., J. Castanet, and A. de Ricqles. 1 980. Structure of the dermal scales in Gymnophiona (Am- phibia). Journal of Morphology, 165: 41-54. FIELDIANA: ZOOLOGY HMnwiimHi— i Field Museum of Natural History Roosevelt Road at Lake Shore Drive Chicago, Illinois 60605-2496 Telephone: (312) 922-9410 ■am: