Lahyi'inthodont Aniphibian /r&m Northumherland. 183 



mutilated. They He immediately behind the head, at the left 

 side of the speeimen, towards the ventral aspect; two are a 

 little in advance of the third. They all have the surface 

 covered with a minute reticulation of raised lines, which assume 

 a radial disposition, as if from centres of growth. Behind the 

 plates, on the left or ventral side of the body, there is a sort 

 of roll, as it were, extending some way backwards, which 

 seems to be composed of minute elliptical scales ; they are, 

 however, very indefinite ; their exact form could not be de- 

 termined. 



The vertebras, of which there are twenty-three or twenty- 

 four, are very apparent, but their precise form is rather diffi- 

 cult to make out ; they are nevertheless in regular order, but 

 are somcAvhat obscured by the matrix. They each bear a long, 

 compressed or flattened, plate-like dorsal spine, which is as 

 high or a little higher than the centrum ; its dorsal or free 

 margin is truncated and serrated ; below it is contracted in 

 the antero-posterior direction, and, expanding above, somewhat 

 resembles a fan, the resemblance being heightened by the 

 strong radiating striaj that cover the sides. They are very 

 similar to the vertical processes of Urocordylus Wandesfordn^ 

 but more particularly agree, in proportion and character, with 

 the subvertebral bone or spine. The three or four terminal 

 posterior vertebrae have in addition subvertebral bones similar 

 in form and size to tlie dorsal spines. From this fact it would 

 ap})ear that these three or foui* vertebras belong to the tail ; 

 and if the new species is as rich in caudal vertebras as U. 

 Wandesforduy our specimen must have lost at least seventy 

 of the bones of its tail. U. reticulatus has therefore about 

 twenty trunk or precaudal vertebras, the number that is found 

 in Prof. Huxley's s])ecies. The vertebras are about yL inch in 

 length, and in height I inch, including the dorsal spine ; the 

 height of the caudal vertebras, measuring from the U})])er 

 margin of the dorsal spine to the lower margin of the subver- 

 tebral bone, is | inch. The zygapophyses project laterally as 

 well as forward and backward. 



There are slight indications of anterior and posterior limbs ; 

 but the appearances are too vague to be worthy of further 

 notice, beyond that a fragment of bone seems to mark the 

 place of the posterior limb near the termination of the trunk- 

 vertebras. And not far from this point there is also a small 

 bone, which is probably one of the phalanges. 



The length of the specimen, including the head and ti-unk- 

 vertebrw, is only one-fourth that of tiie same parts of U. 

 Wandesfordii] we may therefore conclude that the latter 

 species is lour times the size of U. reticidafus. When perfect, 



