16 Mr. H. Seeley on Cambridge Palaeontology : — 



of gnathopoda ; i, second pair of ditto ; k, I, first and second 

 pairs of pereiopoda ; m, third pair of ditto ; n, fourth pair of 

 ditto ; o, fifth pair of ditto ; s, fourth pair of ditto ; t, fifth pair 

 of ditto; u, sixth pair of ditto; z, telson. 



Fig. 3. Plutyscelus serratus, female adult. 



Fig. 4. Ditto, ditto, young. 



b, anterior antenme ; c, posterior ditto ; h, i, gnathopoda ; k, I, first 

 and second pairs of pereiopoda ; m, n, third and fourth pairs of 

 ditto ; o, fifth pair of ditto ; p, first pair of pleopoda ; s, 

 fourth pair of ditto ; t, fifth pair of ditto ; u, sixth pair of ditto ; 

 z, telson. 



II. — Notes on Cambridge Palaontology. 

 By Harry Seeley. 



IV. Some new Upper Greensand Echinoderms. 



Hemiaster M'Coyii, 



Outline oblong, oval, slightly flattened at the anterior extremity, 

 longer than wide ; height two-thirds of the length. The most 

 elevated part is a little behind the apex, the widest part a little 

 anterior to the middle. The transverse section is oval. Upper 

 side slightly convex, sloping down towards the anterior end. 

 Under side slightly convex ; the part anterior to the mouth 

 depressed. Anal side nearly vertically truncated ; anterior 

 end round. Ambulacra straight, unequal, very slightly im- 

 pressed. The odd ambulacrum is formed of straight zones, 

 each composed of about a dozen pairs of round pores, which 

 are placed obliquely and rather wide apart ; the pores are 

 close together. The anterior ambulacra consist of a similar 

 number of pores, which are smaller and closer together. The 

 posterior ambulacra are very short, the zones consisting of 

 about four pairs of pores. Mouth transversely oval, bordered 

 by a little groove, and placed in the anterior third of the shell. 

 Anus oval. The fasciole is wide and 7-sided; it is angular 

 posteriorly, with a short side anteriorly : the posterior and 

 shorter pair of lateral sides is parallel ; the granules of which 

 it is formed are very dense, and only just visible to the naked 

 eye. The shell is very thin, and covered with comparatively 

 large tubercles. 



This well-marked Urchin is so distinct as not to admit of 

 comparison with any form with which I am acquainted. Its 

 nearest relative is a more globular form which occurs with it. 



Rare. Coll. University ; J. Carter, Esq. 



Salenia (? Hyposalenia) Woodwardi. 

 Round, greatly depressed. Ambulacral areas narrow and straight, 



