382 Reviews — G. A. Boulenger*s Extinct Reptilia. 



Suborder II. Pythonomorpha. 9 or 10 cervical vertebrae. Extremities paddle- 

 shaped, with hyperphalangy. 



Suborder III. Lacertilia. 8 or 9 cervical vertebrae. Fibula reduced proximally ; 

 fifth metatarsal reduced in length and strongly modified. 



Suborder IV. Rhiptoglossa. 5 cervical vertebrae. Extremities pincer-shaped ; 

 all the metatarsals reduced in length and strongly modified. 

 B. No trace of a pectoral arch. Caudal hypapophyses disconnected distally. 



Suborder V. Ophidia. 



Figures of the hind limb are added, the so-called Hydrosaurus 

 lesinensis of the Cretaceous being selected as a typical representative 

 of Dolichosaurus. 



The left mandibular ramus of a small Ehynchocephalian reptile, 

 also in the Museum of the Royal College of Surgeons, forms the text 

 of Mr. Boulenger's third contribution. An examination of the matrix 

 suggests that the specimen was probably obtained from the Lower 

 Oolites of Wiltshire ; and the left maxilla of a nearly similar reptile, 

 from the Purbeck Beds of Swanage, is recorded as having been, 

 recently acquired by the British Museum. These fossils are believed 

 to be referable to Homoeosaurus, and the first is described and figured 

 as the type of a new species, H. major. To the same species is also 

 assigned a mandible from the Kimmeridgian of Hanover described 

 by Struckmann in the Zeitschr. deutsch. geol. Ges. vol. xxv. p. 249, 

 pi. vii. Some remarks on the systematic position of Homoeosaurus 

 follow ; and after several critical observations in regard to the 

 non -diagnostic character of most of the existing definitions of the 

 Rhynchocephalia and the component families of the order, the 

 following revised table is appended : — 



Order Ehynchocephalia. 



Suborder I. Proterosatjria. Each transverse segment of the plastron composed 

 of numerous pieces. Pubis and ischium plate-like. Fifth metatarsal not 

 modified. 



Vertebrae conically excavated at either end, with persistent notochord, all 

 with intervertebral hypapophyses ; limb -bones without condyles ; humerus 

 with entepicondylar foramen 1. Falaohatteriidee. 



Vertebrae fully ossified, cervicals opisthocoelous, dorsals biconcave ; no hypa- 

 pophyses between the dorsal vertebrae ; limb-bones with condyles ; humerus 

 with entepicondylar foramen or groove 2. Froterosauridce. 



Suborder II. Ehynchocephalia vera. Each transverse segment of the plastron 

 composed of three pieces, a median angulate and a pair of lateral. Pubis and 

 ischium elongate, and fifth metatarsal modified, as in the Lacertilia. 



A. Nasal openings distinct. Mandible with coronoid process, the rami not united 



by suture. Vertebrae deeply biconcave. 



Humerus with ectepicondylar and entepicondylar foramen; ribs with uncinate 



processes ; all the vertebrae with intercentral hypapophyses. 3. Hatteriida. 

 Humerus with entepicondylar foramen ; ribs without uncinate processes ; no 



hypapophyses between the dorsal vertebrae 4. Sommosauridts. 



B. Nasal opening single. Mandible without coronoid process, the rami united 



in a solid symphysis. Vertebrae fully ossified, feebly biconcave ; no hypa- 

 pophyses between the dorsal vertebrae. Humerus with ectepicondylar foramen 

 or groove. 



Snout short, ending in a beak 5. Shynchosauridm. 



Snout crocodilian in shape, with toothed premaxillaries. 



6. ~" 



