CHAPTER XVII. 



THE M1CROSAURIAN FAMILY AMPH1BAM1D/C, FROM THE COAL MEASURES 



OF MAZON CREEK, ILLINOIS. 



Family AMPHIBAMID^E new family. 



Small, lizard-like, terrestrial or semi-aquatic, megacephalic microsaurians, 

 known from 3 species. The family characters are the huge size of the head as 

 compared to the body, the short, stumpy body with about 25 short dorsal verte- 

 bras, a very short tail, phalanges clawed, pubis of calcified cartilage, sclerotic 

 plates in the orbit to the number of 29 or 30 in each, ventral armature well 

 developed. Teeth anisodont, sharp, conical, non-striate. 



Two genera are associated in this family: Amphibamus grandiceps Cope, known 

 from three nearly complete skeletons; A. thoracatus Moodie, known from a single 

 incomplete skeleton; Cephalerpeton ventriarmatum Moodie, anterior portion of body 

 and skull. The species are all from the Mazon Creek shales and the family seems 

 unrepresented elsewhere. It may be necessary to compare the Amphibamidas with 

 the Hylonomidae when the latter group is better known, but in the light of our 

 present knowledge the two families are distinct. 



The genera may be distinguished as follows: 



. I. Size small, less than 3 inches in total length, skull with deeply incised tympanic notches (ear-slits) . .Amphibamus 

 II. Size relatively large, body-length 6 inches or more, teeth distinctly anisodont, skull with nearly even 



posterior table, limbs very long, ventral armature highly developed Cephalerpeton 



Genus AMPHIBAMUS Cope, 1865. 



COPE, Proc. Phila. Acad. Nat. Sci., 1865, pp. 134-137. Geol. Surv. Ills., II, pp. 135-141, pi. xxxii, i text-fig. 

 HAY, Proc. Am. Phil. Soc., xxxix, p. 120, 1900. 

 MOODIE, Jour. Geol., xvu, p. 81, fig. 24, 1909. 



Type: Amphibamus grandiceps Cope. 



The publication of the type species of this genus began the researches of Pro- 

 fessor Cope on the extinct Amphibia of North America, which he continued for so 

 many years with such excellent results (105-177). The description was based on a 

 single specimen (plate 3, fig. 7) belonging to Mr. Joseph Evans, of Morris, Illinois, 

 who loaned it to Dr. Worthen for the Illinois Geological State Survey (107), in order 

 that it might be described. The type has been destroyed by fire ; so I am informed 

 by Mr. L. E. Daniels, of Rolling Prairie, Indiana. There are two other known speci- 

 mens of the species. One is in the collection of Mr. Daniels and the other No. 794, 

 of Yale University Museum. 



This genus may be clearly separated from all the other microsaurians by char- 

 acters which are peculiar to the form. Among these may be mentioned the posses- 

 sion of sclerotic plates in the eyes; the large size of the orbits in comparison with 

 the dimensions of the skull; the short, broad form of the body; the very short tail; 

 the possession of a calcified cartilaginous pubis; clawed phalanges; presacrals 22. 

 The character which places the genus distinctly in the Microsauria is the possession 

 of long, slender, curved ribs, first detected on Mr. Daniels's specimen (plate 14, figs. 



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