184 ME. H. G. SEELEY ON OSSEOUS UESEMBLANCES 



(/helonian, the maxillary and malar below, the postfrontal and 

 quadrate behind, though in Testudo the bone which represents 

 the quadrato-jugal, while penetrating the suture between the 

 postfrontal and malar, does not reach the orbit ; above are the 

 postfrontal, frontal, and prefrontal, the latter bone in Chelonians 

 rarely being distinct ; and in front is a small lachrymal, which is 

 not found in Chelonians. 



The nostril differs from that of a Chelonian in having the pre- 

 raaxillaries prolonged upwards to be embraced by the front of the 

 nasal bones. 



There is a resemblance to Chelonians in the median bones of 

 the roof of the skull all being double. 



The quadrate bone is vertical in Hatteria, and suturally wedged 

 in the skull ; but it has a form of its own and a peculiar antero- 

 posterior perforation ; and the back of the skull has little in 

 common with Chelonians. 



The pelvis is very like that of Emysaura, and in old animals 

 would probably approach near to Testudo. 



The ischium has the Chelonian shape, with a not dissimilar 

 posterior tuberosity ; it is, however, united to the pubis only by a 

 strip of cartilage as in Iguana. The pubes have between them a 

 diamond-shaped cartilage in front, which, fully ossified, would give 

 the pubic bones a form like that of the old Testudo. The bones 

 ai'e perforated, as in Lizards, by the obturator nerve. The ilium 

 inclines a little backward, is flattened, has the sides subparallel, 

 but, as in Lizards, extends beyond the point of attachment to the 

 sacrum. 



§ 7. The Serpent-characters of Chelonians. 



In the Boa there is a similar prolongation of the parietal and 

 occipital bones backward into a crest and spine. The maxil- 

 lary bone is similarly introduced into the base of the orbit ; and, 

 as in Testudo, the posterior boundary is made by the postfrontal 

 bone, the upper boundary by the frontal, and the front boundary 

 by the prefrontal. In the Boa and in the poisonous group the 

 small premaxillary is similarly toothless. And though the anterior 

 nares are double in Serpents, they are bordered by the nasal, 

 maxillary, and premaxillary bones as in Chelonians. 



The method of articulation in the vertebral column, and the 

 double hypapophysis in the tail preclude further comparison. 



