Q 



1885.] ° [Cope. 



paneled outwards. Its tarsal articular suface forms an acute angle with 

 the long axis of the shaft, presenting outwards. It has besides a slight 

 distal transverse truncation. The fibula has a robust head and is slender 

 distally. The tarsus consists of seven bones. These are a tibiale, an in- 

 termedio-centralo-fibulare, and a tarsale corresponding to each of the five 

 metatarsals. There is a foraminal notch on the internal edge of the inter- 

 medio-centralo-fibulare, next to the tibiale. The bones of the foot beyond 

 the tarsus are well distinguished from each other. The metatarsals are 

 rather slender, and are considerably longer than the phalanges of the first 

 row. The phalanges are not much shortened, but diminish in length 

 regularly to the end. The ungual phalanges are not preserved in a per- 

 fect condition on any of them. The proximal portion remains on the 

 second digit, and it is depressed, offering no indication of a claw. The 

 first toe is not shortened, and appears to be longer than the second. Its 

 distal segments are lost. Neither the metatarsals nor the phalanges have 

 distinct condyles, but are truncate in the vertical direction. 



Abdominal protective armature is present in the form of osseous rods. 

 Several of these rods form a single girdle. They are not connected with 

 the ribs. 



The pelvis is partially preserved in the specimen on the slab. Both 

 pubes and ischia are well developed, and if there is any obturator foramen 

 it is very small and median in position. It probably does not exist, but I 

 am precluded from certainty by the condition of the specimen at the point 

 of crossing of the median and transverse sutures. The pubis is not so 

 large as the ischium, and has a foramen near its posterior border. The 

 ilia have less transverse, and greater longitudinal expanse than the pubes, 

 and are in contact on the middle line throughout most of their length. 



Affinities. It is not easy to decide as to the position of this genus. 

 While many of its characters are reptilian, some of them are batra- 

 chian. Of especial interest in this connection is the structure of the pel- 

 vis. Its characters are only like those of some of the Urodele Batrachia, 

 and the Theromorphous Reptilia. It is, however, quite certain that it does 

 not belong to any known family of either class. The vertebrae might be 

 those of a Theromorph reptile, and the pelvis also agrees with that of those 

 animals. The abdominal rods are found in species of that order referred 

 to the genus Theropleura. The ribs and tarsus are however of an en- 

 tirely different type. The former would refer the genus to the Rhyncho- 

 cephalia or the Sauropterygia, and there is nothing known in its structure 

 which positively forbids either reference, unless it be the character of the 

 pelvis. It differs from the types of the Batrachia which it most resem- 

 bles, the Protonopsidoa, in the replacement of the cartilaginous plate 

 which represents the pubis by two osseous plates. It presents a near 

 resemblance in important characters to the genus Ichthycanthus* which 



* I refer to the Ichthycanthus ohiensis from the description and from memory, 

 as the specimen is not at present accessible. The I. platypus is one of the Rhach- 

 itomi, and has in the tarsus, astragalus, calcaneum, navicular, and five dis- 

 tinct tarsals of the second row. 

 PROC. AMEB. PIIILOS. SOC. XXIII. 121. R. PRINTED SEPTEMBER 20, 1885. 



