EMYDOSAURIA, 273 
Order EMYDOSAURIA. 
Emydo-Sauriens, Blainville, Bull. Soc. Philom. 1816. 
Loricata, Merrem, Tent. Syst. Amph. 1820. 
Emydosauri, Gray, Ann. Phil. (2) x. 1825. 
Crocodili, Wagler, Syst. Amph. 1830. 
Quadrate bone immovably united to cranial arches ; two hori- 
zontal bony temporal arches. Cervical and dorsal ribs mostly two- 
headed, the middle dorsals articulating with the transverse processes 
of the neural arch. Sternum and interclavicle present; seven or 
eight transverse series of “ abdominal ribs,” not connected with the 
vertebral ribs, each composed of four ossicles forming an angle 
directed forwards. Teeth present in the jaws, implanted in alveoli. 
Ventricle of the heart divided by a complete septum. Pectoral and 
abdominal cavities separated from each other by a muscular dia- 
phragm. Anal opening longitudinal. Copulatory organ present, 
simple. 
The existing members of this Order, the most highly organized 
of all recent Reptilia, cannot in my opinion be divided into seyeral 
families. The fact that Zomistoma is altogether quite as much 
related to the long-snouted Crocodiles as to the true Gavial is 
opposed to the separation of the Gavialide. The only constant 
important character between the Crocodiles and the Alligators is 
the increased number of mandibular teeth in the latter, which is 
the same asin Zomistoma. The well-known Cuvierian character of 
the fourth mandibular tooth fitting into a notch in Crocodilus and 
into a pit in Alligator is not absolutely diagnostic, since, as already 
observed by Huxley, specimens of the short-snouted Crocodilus 
palustris occur which agree in this respect with the Alligators, 
whilst, on the other hand, Cope has described a supposed Alligator in 
which the fourth tooth, on one side, fits into a notch. The short- 
snouted species of Crocodilus and Osteolemus further agree with the 
Alligators in the mandibular teeth biting inwards of the maxillary 
teeth instead of between them. Ostcolemus, although agreeing 
with Crocodilus in its dentition, stands in most other respects nearer 
the Alligators. A rather trifling character, recently pointed out by 
Baur, viz. the absence of a more or less developed pointed process 
on the free border of the quadratojugal, distinguishes Alligator and 
Caiman from the other Crocodilians 
