ISODECTES PUNCTULATUS COPE 399 



more could be wished for. I have no emendations to make of Cope's 

 determinations, save to say that the phalangeal formula was certainly 

 2, 3, 4, 5, 4. I accept Cope's interpretation of the tarsus, as shown in 

 the figure, with the proviso that possibly the proximal row may be 

 composed of the three bones, tibiale, intermedium, and fibulare, but 

 I do not think so. The bones exhibit full chondral ossification, and 

 not perichondral alone, as is the case with the Branchiosauria, and 

 many of the Microsauria also, probably. Whether microsaurian or 

 reptilian in nature, the presence of such a tarsus, with its fusion of 

 intermedium and centrale is of great interest, since this is the oldest 

 known tarsus and foot of an air-breather in existence, the Linton 

 horizon, of middle or lower Pennsylvanian being lower than others 

 hitherto known yielding Microsaurian remains. 



The imperfect left hand is the only part preserved of the fore 

 limbs. Four metacarpals are, however, clearly shown, and two 

 ossified carpals, together with several phalanges. 



The apparent absence of ventral ribs and the possible absence of 

 hypocentra would seem to remove our form from direct ancestral 

 relationships with the later reptiles, but there is not a solitary char- 

 acter which can be discovered in the specimen that is not reptihan. 

 That the specimen pertains to the same species, or even genus, as 

 that represented by the type specimen of Tuditanus punctulatus is 

 very doubtful, and Cope was not assured of the identity. That speci- 

 men indicates an imperfect chrondral ossification of the bones, and 

 there are no signs of carpal bones, though the metacarpals are pre- 

 served. Until further evidence is forthcoming, the present specimen 

 may be known as Isodectes copei, though the generic identity with 

 the Permian form is very problematical. 



M. Thevenin believes that his Sauravus is a rhynchocephalian ; 

 I cannot agree with him. In all probability the head of Sauravus 

 will be found to be stegocrotaphous, of the Stegocephalian or Coty- 

 losaurian type. If the parasphenoid is found to be considerably re- 

 duced in Sauravus costei and Isodectes copei, even though there be two 

 occipital condyles, they must both be referred to the ReptiKa; if not, 

 they must be classified with the Microsauria. That the two forms are 

 related one cannot doubt. But, wherever they may be finally placed, 

 both clearly show reptilian characteristics. It is clear that the primi- 



