APPEN DEX. 
Arr. IX.—A new Order of Extinct Reptiles (SAURANODONTA), 
rom the Jurassic aes of the Rocky Mountains; by 
Professor O. C. Mar 
THE absence of the genus Jchthyosaurus in the extinct fauna 
of this country has long been a noteworthy feature, for up to 
the present time no traces of it have been detected, although its 
remains are especially abundant in Europe. An interesting 
specimen recently discovered in the Rocky Mountain region 
_ presents, in most of its skeleton, the characteristics of that 
_ genus, but is without teeth. The vertebree, ribs, and other por- 
_ tions of the skeleton preserved, cannot be distinguished from 
_ the corresponding parts of Ichihyosaurus, and many features 
_ of the skull show a strong resemblance. The general form of 
_ the skull is the same. The great development of the premax- 
 ilaries; the reduced maxillaries; the huge orbit defended by 
a ring of bony plates, a = present, but the jaws Lees en- 
wis edentulous, and destitute even of a dentary groove 
| e proportions of oe reptile were very similar to those of 
q So tenes The skull is about two feet (600) in length, 
_ and the facial portion especially produced. The orbits are very 
large, and the space between them is 140™. The sclerotic ring 
_ is composed of only eight plates. Its diameter at the base is 
— 106™, and at the apex 58". These plates are not arranged 
_ in a nearly flat ring, as in Jchthyosaurus, tae form the basal seg- 
ment of an elongated cone, as in the eyes of some birds. The 
_ vertebree are short, and deeply bi-concaye. The neural arch is 
articulated to the centrum. One trunk vertebra measures 85™ 
in width, 88™" in length on the floor of the neural canal, and 
= 21>" between the centers of the two rib articular faces of the 
_ same side. The len ngth of the entire animal was about eight or 
nine feet. The remains at present known are all in the Museum 
of Yale College. 
Am. Jour. Sc1.—TuHIRD p Santee, Vor. XVI, No. 97.—Jan., 1879. 
