NATURAL SCIENCES OP PHILADELPHIA. 141 



Parker), an identification which cannot probably be maintained. 

 The connections of the pterotic, where present, are very different. 

 The bone in question is present in Edestosauriis tortor, Cope. 



Sixthly. Prof. Marsh completes almost entirely our knowledge 

 of the anterior limbs. The previous descriptions of these mem- 

 bers in Clidastes propython, Cope, Holcodus ictericus, Cope, 

 and other species, had left the number of phalanges and their 

 relative positions, as well as those of the carpals, uncertain ; these 

 points are now happily supplied by Prof. Marsh's important re- 

 searches. 



Seventhly. He has done much for the pelvic arch and hind 

 limbs. He was the first to announce the existence of both, and 

 actually described the pelvis of Edestosaurus dispar; the speaker, 

 however, first described the hind limb in Liodon c?'assa)-tus and 

 L. dyspelor, Cope. Prof. Marsh is in error when he says the 

 " absence of these extremities in the Pythonomorpha was consid- 

 ered satisfactorily established." I had never stated that they 

 were certainly absent, and the last time I wrote observed that this 

 order " possessed an anterior pair only, or with the posterior pair 

 so reduced as to have been insignificant." 1 They appear, ac- 

 cording to Marsh, to have been relatively small in some of the genera. 

 In Liodon dyspelor, Cope, the anterior are the smaller. Prof. 

 Marsh lays students under especial obligation for his determina- 

 tions of the pelvic elements and the excellent figures of all the 

 parts connected with the support of the hind limb. His figure of 

 the fore limb is also highly important, as it will be difficult soon 

 to duplicate his beautifully complete specimen. 



In subsequent pages there are six additional species described, 

 bringing up the number from the Kansas Cretaceous to twenty- 

 three. Two new genera are proposed, viz., Lestosaurus for those 

 previously referred by myself to Holcodus, Gibbes, and Rhino- 

 saurus for species allied or belonging to Liodon. As to the for- 

 mer, it is no doubt a well-marked genus, and I am willing to 

 believe Prof. Marsh's opinion, that it will not include Gibbes' Hol- 

 codus acutidens, will turn out to be well founded ; but there is, 

 on the other hand, insufficient evidence to show that it is not 

 Platecarpus, Cope. If Liodon curtirostris be referred to it, it 

 will very probably prove to be Platecm-pus, as that species pre- 

 sents palatine teeth, much as in P. tympaniticus, and the pleuro- 

 dont character is not wanting in some of the other species. Rlii- 

 nosaurus includes such species as Liodon proriger, Cope. As 

 the name has been used two or three times before, it may be al- 

 tered to Rhamphosaurus, but I have always had doubts that the 

 conic projecting snout would distinguish the species generically 

 from the true Liodon, with which it agrees in dentition. The 

 type of Liodon, L. anceps ord., is, however, very little known. 



, ' Hayden, Geol. Survey of Wyoming, etc., 1870, p. 385. 



