98 BAUR. [Vol. I. 



There seem to be the larger number of connections with the 

 Testudinata. 



The cervical ribs of the Testudinata are entirely rudimentary. 

 Hoffmann ^ has shown that they are developed in the embryos. 

 In the adult Testudinata there are often well-developed dia- 

 pophyses and parapophyses in the anterior cervicals. The former 

 are connected with the neurapophyses, the latter with the body 

 of the vertebra ; both touch each other. Therefore we have a 

 real para-diapophysis, and, consequently, if a rib should be 

 developed, a rib with a capitulo-tuberculum. That the an- 

 cestors of the Testudinata had well-developed ribs on the 

 cervicals is shown, not only by Hoffmann's researches, but also 

 by the still developed para-diapophyses. 



The pelvic arch of the Nothosauridae is only comparable with 

 that of the Testudinata. The shape of the pubis is very much 

 alike in both. The obturator foramen is usually present in the 

 Nothosauridae, but is generally situated at the border of the 

 bone. In the Testudinata the obturator foramen is generally 

 wanting. Rudiments of it I find, however, in a specimen of 

 Eretmochelys imbricata, and I do not doubt that a close exami- 

 nation of the pubic bones in the oldest Testudinata will show its 

 rudimentary presence. The ischia are very much alike. 



The femur of Nothosaurus, according to H. v. Meyer, is only 

 comparable to that of the Testudinata. 



The humerus of the Lariosauridae and Nothosauridae has 

 the ectepicondylar foramen, like the Lacertilia, Rhynchoce- 

 phalia, and Testudinata. 



Other resemblances are to be found in the sacral and caudal 

 vertebrae, in the condition of the chevrons, etc. 



The sacral vertebrae of both the Sauropterygia and Testudi- 

 nata have well-developed para- and diapophyses, to which the 

 sacral rib is connected ; the same is to be found in the anterior 

 caudals ; in the posterior caudals the para-diapophyses become 

 rudimentary. In all the Sauropterygia- the chevrons are at- 

 tached only to the posterior part of the vertebrae, not between 

 two vertebrae, as in the Rhynchocephalia, Crocodilia, etc. 



The same has place in the Testudinata ; if chevrons are de- 



* Hoffmann, C. K. Uber das Vorkommen von Halsrippen bei den Schildkroten. 

 Beitrage zur verzleichenden Anatomic der Wirbelthiere, pp. 138-150. Leiden- Leipzig, 

 1879. 



