DE. GUNTHER ON THE ANATOMY OE HATTEEIA. 
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characters, by which it is distinguished from the second section Cataphracta (= Tor- 
toises and Crocodilians + Amphisbsenians). The division proposed by Stannius into 
Streptostylica (= Snakes and Lizards + Amphisbsenians) and Monimostylica (Tortoises 
+ Crocodilians) is founded essentially on the same characters as that of Gkay. Hatteria 
would not enter any of the divisions defined in those two systems. Professor Owen 
refers the recent Reptiles to four coordinate orders — Chelonia, Lacertilia, Ophidia, and 
Crocodilia ; Hatteria would probably enter the second, inasmuch as the character of 
“proccelian vertebrae” assigned to this order, is the only one by which Hatteria would 
be excluded, but the Geckos, which are Lacertilians in Professor Owen’s system, also 
have amphicoelian vertebrae. In the Crocodilia, likewise, this is not considered an 
ordinal character, but is used for the distinction of the suborders. 
In these three systems the Crocodiles are removed from the Lizards, into a distinct 
order or section, on the ground of osteological characters as well as on account of the 
higher organization of their soft parts. Now in Hatteria the modifications of the 
Lacertian skeleton extend to the same parts as in the Crocodiles (except the anterior 
ribs and thoracic sternum), although they are frequently of a different nature ; and the 
repetition of Lacertian characters in its soft organs is in some measure counterbalanced 
by the absence of copulatory organs. Therefore we cannot hesitate to claim for it a rank 
higher than that of a family. The presence of a double bar across the temporal region, 
the intimate and firm connexion of the os quadratum with the skull and pterygoids, the 
erect ilium, and the uncinate processes of the ribs are characters by which a tendency 
towards the Crocodilians is manifested ; but here the resemblance ceases ; and the affini- 
ties of Hatteria with the Lizards are far more numerous and of greater importance. I 
need only mention the structure of the heart, of the organs of respiration and digestion, 
the absence of a diaphragm and of peritoneal canals, the transverse anal cleft, the 
absence of an external ear, the free tongue, &c. Yet were we to associate it with the 
Lizards in one group, the unity of this group would be entirely destroyed. I pro- 
pose, therefore, the following modification of Stannius’s division of recent Reptilia, 
adding a few of the characters which appear to be of special importance in the determi- 
nation of the affinities of Hatteria : — 
EECENT REPTILIA. 
I. Squamata. Anal cleft transverse. Copulatory organs paired, if present. All the 
ribs single-headed, sacral vertebrae two or none. 
First order : Ophidia. Quadrate bone articulated to the skull ; brain-capsule entirely 
osseous ; rami of the mandible united by ligament. Copulatory organs present. 
Second order : Lacertilia. Quadrate bone articulated to the skull ; parts of the ali- 
and orbito-sphenoid regions fibro-cartilaginous ; rami of the mandible united by 
suture ; temporal region without, or with only one horizontal bar. Copulatory 
organs present. 
