352 Mr. H. Seeley on two new Plesiosaurs from the Lias. 



over the base of the cephalothorax, and is armed on the upper 

 part and sides with about fifty sharp-pointed yellow spines; 

 two, much larger than the rest, are unequally forked, having a" 

 short spine on their outer side, and are of a red-brown colour, 

 the anterior surface of the prongs and a broad annulus at their 

 base being much the darkest; these spines are placed trans- 

 versely on the most elevated part of the abdomen ; it is of a 

 pale dull-yellow hue, and has small black prominences distri- 

 buted over its upper part and sides ; the former has a narrow 

 brown band extending from its anterior extremity to the spin- 

 ners, near the middle of which there are two short brown lines 

 curved towards each other, comprising in the interval between 

 them a pair of spines ; and the latter are marked with dark- 

 brown transverse lines, bordered anteriorly with pale yellow ; 

 the under part is corrugated, and minute, depressed, brown 

 spots are disposed in rows in the curved transverse furrows; 

 the sexual organs present a narrow transverse orifice, and have 

 a reddish-brown hue, that of the branchial opercula being yel- 

 lowish-brown. 



I have much pleasure in associating the name of my valued 

 friend and correspondent, R. H. Meade, Esq., with this very 

 remarkable Spider, which forms a connecting link between the 

 species of the genera Epe'ira and Acrosoma. 



XLI. — On two new Plesiosaurs, from the Lias. By Harry 

 Seeley, F.G.S., of the Woodwardian Museum, Cambridge. 



[Plates XIV. & XV.] 



Thomas Hawkins, Esquire, to whose zeal English science owes 

 many exquisitely wrought-out Reptiles of the Liassic seas, pre- 

 sented to the University of Cambridge a series of Saurians 

 which grace the walls of the Woodwardian Museum. Two are 

 Plesiosaurs, both of new species : one of them, already famous 

 for having the unanchylosed bones described by the late Lucas 

 Barrett in his paper on the Plesiosaurian atlas and axis, displays 

 limbs, ribs, all the dorsal vertebrae, and much of the neck ; the 

 other and smaller fragment has a part only of the neck and back, 

 ribs, episternum, coracoid, scapula, and clavicle. 



The larger fossil seems to have been imbedded laying on its 

 back, with the neck swayed laterally ; but all the vertebrae now 

 rest on the left side, so that the neck is curved, as though the 

 head had been drawn back. Except the first four caudal verte- 

 bra?, the tail is wanting, and many vertebrae are absent from the 

 middle of the neck. Mr. Barrett considered the remains to in- 



