TEICLEIDUS SEELETI. 149 



Genus TEICLEIDUS, Andrews. 



[Ann. Mag. Nat. Hist. [8] vol. iv. (1909) p. 419.] 



Small Plesiosaurs in which the skull is short and broad, with twenty teeth on each 

 side (five on premaxilla, fifteen on maxilla). Pterygoids bear well-developed processes 

 for union with the basisphenoid. Parasphenoid broad and abruptly truncated in front. 

 Quadrate region apparently consisting of two elements C? quadrate and quadruto-jugal). 

 Teeth long, slender, and very sharply pointed; the anterior maxillary teeth enlarged. 

 Neck rather more than three times the length of the skull, and consisting of about 

 twenty-six vertebras (including the atlas and axis) ; the centra with strongly concave 

 articular ends, which are much wider than high. The cervical ribs have a prominent 

 anterior angle. In the shoulder-girdle there is a large interclavicle with well-developed, 

 elongated clavicles. The humerus is stout and is not greatly expanded at the distal 

 end, where it articulates with four elements, the radius, ulna, pisiform, and a small 

 accessory postaxial ossicle, probably sometimes wanting. Femur more slender than 

 humerus, and articulating with two bones only. 



It has been found necessary to establish this genus for (he reception of a small 

 Plesiosaur which differs in some important respects from Cryptocleidus, Murcenosaurus, 

 and other forms with which it has been compared. The chief peculiaritieci are the 

 possession of well-developed processes of the pterygoids for union with the basis cranii, 

 the presence both of well-developed interclavicle and clavicles, and the distal 

 articulation of the humerus with four elements. Only one species is known at 

 present. 



Tricleidus seeleyi, Andrews. 



[Plate VIII. ; text-figs. 72-77.] 

 1909. Tricleidus seeleyi, Andrews, Geol. Mag. [8] vol. iv. p. 421, text-figs. 1, 2. 



Type S^yecimen. — An imperfect skeleton including the disarticulated bones of the 

 skull (text-figs. 72-75), the mandible (PI. VIII. figs. 1, la), cervical vertebrse(Pl. VIII. 

 figs, 8, 8 a-d), pectorals (PI. VIII. fig. 7), five dorsals (PI. Vlll. figs. 5, 6), and two 

 caudals ; num.erous dorsal and ventral }-ibs, coracoids, scapulae, clavicles, interclavicle 

 (PL VIII. fig. 3); fore paddles (imperfect) (text-fig. 77), one pubis; imperfect hind 

 paddles (PI. VIII. figs. 4, 4 a) (R. 3539, Leeds Coll. 39). The pectoral girdle and 

 fore paddle have been figured in the Geol. Mag. loc. cit. supra. 



The following account of the skeleton in this species is founded on the type and 

 only known specimen. 



Skull (text-figs. 72-75). — In the skull here described most of the bones are 

 separate from one another and, in many cases, much crushed and broken ; some are 



