Squaniata — Ophidia. 



25 



armour of bony dermal scutes. The limbs may be adapted for 

 walking on land, or modified into paddles for swimming. In 

 the skull the proximal end of the quadrate bone is more or less 

 movably articulated ; the lower temporal arcade is wanting ; 

 the post-orbital is generally fused with the post-frontal ; the 

 palate is more or less open, the pterygoids being nearly always 

 separated by an intei-val from one another, and the premaxillae 

 ai-e frequently united. The vertebrte are generally procoelons 

 ("concave in front), although more rarely they are amphicoelous 

 (bi-concave). True abdominal ribs are never developed. The 

 carpus has but a single centrale, and the precoracoid process is 

 often well marked. 



Sub-order 1. — Ophidia (Serpents). 



Serpents are rarely met with in a fossil state, but a few 

 such remains have been obtained from the Tertiary rocks. The 

 earliest Ophidian represented in the Collection is the Palceopliis 



Fig. 29. — Vertebrae of Palceopliis Uiplueas (Owen), from the Lower Eocene, Sheppey. 

 A, haemal; b, anterior; and c, left lateral views of a trunk vertebra, wanting most 

 of Ihe neural spine ; zs, zygosphene ; c, costal articulation. 



toKapicus, a serpent about 12 feet in length, obtained fi-om the 

 London Clay of Sheppey ; from the Middle Eocene of Brack- 

 lesham we have a still larger form, the Palceophis typJiceus, a boa- 

 constrictor-like snake, considered to be marine, that attained a 

 length' of 20 feet, and also a smaller species, P. porcatiis. 



A 1! c 



Serpents. 

 Table-case, 

 No. 3. 



Paleeophis. 



Fig. 30.— (A) Hjemal, (B) Anterior, (C) left lateral views of a trunk- vertebra of 

 Paleryx rhomhifer (Owen), from the Eocene Phosphorites of Caylux, France. 

 c, costal articulation; zs, zygosphene. 



The Upper Eocene sands of Hordwell have yielded numei'ous Paleryx. 

 vertebrae of snakes, but of a much smaller size, namely, Paleryx 



