THE MICROSAURIAN FAMILY AMPHIBAMID^. 1 27 



1,2), by Dr. Hay (316). Its stegocephalian characters are evident in every partic- 

 ular of its anatomy — the roofed skull, the arrangement of the cranial elements, the 

 presence of a well-developed ventral armature, and the digital formula (4 for the 

 hand and 5 for the foot). 



The genus Amphibamiis was regarded by Cope as a representative of a new order 

 of vertebrates which he called (105) Xenorachia. He later (123) abandoned this, how- 

 ever. Fritsch (251), Zittel (642), and others regarded Amphibamus as a branchio- 

 saurian. The exact position of the form was uncertain until 1 900, when Dr. Hay (3 1 6) 

 described the long, curved ribs and suggested its place among the Microsauria. He, 

 however (Cat. Foss. Vert., p. 410), made the mistake of including the branchio- 

 saurian family Protritonidae, under Microsauria, thus confusing the subject further. 

 The genus (462) has not the slightest relationship with the Branchiosauria. 



Amphibamus grandiceps Cope. 



Cope, Proc. Phila. Acad. Nat. Sci., pp. 134-137, 1865; Geol. Surv. Ills., 11, pp. 135-141, pi. xx.xii, and i wood- 

 cut, 1866. 



Hay, Proc. Am. Phil. Soc., .x.\.\ix, p. 120, 1900. 



MooDiE, Jour. Geol., xvii. No. 1, p. 82, fig. 24, 1909. 



MooDiE, Kan. Univ. Sci. Bull., vi, No. 2, pp. 343-349. pl- i, figs, i and 2; pi. 5, fig. 3; pi. 7, fig. i; pi. 11, 

 12, 13, 1912. 



Type: Specimen has been destroyed. There is an excellent specimen (plate 4, 

 figs- 5, 6), No. 794 (1234), in Yale University Museum, and another nearly as good 

 in the possession of Mr. L. E. Daniels, of RolHng Prairie, Indiana. 



Horizon and locality: Mazon Creek shales, near Morris, Illinois. 



The form of the skull of Amphibamus grandiceps Cope is not unlike that of 

 Tuditanus minimus Moodie (462) from the Linton, Ohio, beds, but it is less acumi- 

 nate than in that form. The large size of the orbits is especially striking. The shape 

 of the skull is triangular, with concavities in the posterior table which correspond 

 to the ear-slits so characteristic of Metoposaurus (242) from the Keuper of Germany. 

 The narrowed posterior table of the skull is truncate, as in several other genera of 

 Microsauria, notably Tuditanus and Saurerpeton. In structure the skioll differs 

 but little from many of the other Carboniferous forms, but the arrangement of the 

 elements of the skull is more regular than in other genera. 



The premaxillaries are very small elements in the anterior tip of the skull. They 

 border the nares. The skull is rather peculiar among the Microsauria in the pos- 

 session of a distinct lacrimal. I have detected this element in the cranium of 

 Stegops divaricata Cope. As here defined the lacrimal is triangular, with its pos- 

 terior border formed exclusively by the prefrontal. Its other relations are the nor- 

 mal ones. The nasal is elongate, with the usual relations of that element. The 

 frontal is slightly longer and broader than the nasal. It apparently forms a por- 

 tion of the inner border of the orbit. The parietal foramen lies in the anterior 

 fourth of the parietal, a rather unusual position for this structure. The parietals, 

 as in so many of the Microsauria, together form the largest element of the skull and 

 are roughly a triangular area in the postero-median portion of the skull. The post- 

 parietal and the tabulare are clearly distinguishable and they have the usual rela- 

 tions for those elements. The maxillary, jugal, and quadratojugal together form 

 the greater part of the maxillary border. The postero-lateral angle of the skull is, 



