REPTILIA: LIMNOSCELIS 



33 



Fig. 8. — Limnoscelis paltidis. A, pos- 

 terior dorsal vertebra, from behind; B, 

 twenty-second or twenty-third caudal verte- 

 bra, from the side; C, ulnare. 



than in Captorhinus laticeps Will. The number in Limnoscelis will 

 later be determined with certainty. The first of the series exposed, 

 the eighteenth presacral, has a shallow fossa or flattened surface 

 below in the middle, which fossa increases in depth posteriorly, 

 a very characteristic feature 

 which seems to differentiate 

 the genus from others previ- 

 ously known, especially Dia- 

 sparactus Case. The outHne 

 of the centra, both on the 

 sides and below, anterp-pos- 

 teriorly, is deeply concave. 

 The arch has a marked re- 

 semblance to that of Diadecies, 

 and, according to Broom, to 

 that of Pareiasaurus also, and 

 is very different from the type 

 characteristic of Labidosaurus 

 and Seymouria. It differs from that of Diadectes especially in the 

 absence of all indications of a hyposphene; but, if I am correct, 

 Nothodon, which is of course a diadectid, also lacks the hypo- 

 sphene, rendering the 

 character in conse- 

 quence merely of ge- 

 neric value. 



All the observed 

 ribs are single-headed, 

 but expanded; that is, 

 without an emargi- 

 nation distinguishing 

 the head from the tu- 

 bercle. In Diadectes, 

 or at least in such 

 species as I have been able to study of this genus, the ribs anteriorly 

 are distinctly double-headed. The transverse processes are short 

 throughout the series, scarcely extending on the sides beyond the 

 margin of the zygapophyses. This character has been given by 



Fig. 9. — Limnoscelis pahidis. Posterior dorsal 

 vertebra, one-half natural size. 4, from in front; B, 

 from the side. 



