On Cyrtoma, a new genus of Fossil Echbiida. 181 



mouth, apex elevated, about 32 anambulacral plates with four 

 equal spines on each plate, and four vertical rows of spines be- 

 tween each ambulacrum. Anambulacral plates detached from each 

 other above the disc, below consolidated, ambulacra consisting of 

 one pair of holes disposed zig-zag and close. Alveolus (fig. 4. a.) 

 broad with a very small arch. 



Ordinary size about 1.5 inch in diameter. 



Hab. Bay of Bengal Received from Captain Lloyd. 



IV ECHINOMETRA MEGASTOMA, J. M. t. iv. f. 4, 5. 



Disc oval and depressed at the ends, base arched and recurved 

 round the mouth which is large, 13 anambulacral plates in each 

 short series on the sides, and 15 in the longer series on the 

 ends. 



Hab. Unknown. As. Soc. Mus. 



V. ECHINOLAMPUS ANGULOSUS, J. M. t. iv. f. 6, 7. 



Disc elongated between the posterior ambulacra; rosette 

 consisting of two double rows of pores converging slightly, but 

 not uniting ^towards the disc ; united at the apex, which is also 

 marked by four oviducal holes, testa thin, anambulacral series 

 wedged out before they reach the apex.* 



Hab. Bay of Bengal. 



VI. ECHINARACHNIUS CONCHATUS, J. M. t. iv. f. 8, 9. 



Disc subpentangular, mouth large, and occupying the greater 

 portion of the inferior surface, surrounded merely by a narrow 

 flat margin, in the hinder part of which the anus is placed. Ambu- 

 lacra lanceolate, and converging to a slightly raised apex, in 

 which there are five oviducal holes. 



Hab. Bay of Bengal. Received from Captain Lloyd. 



VII. — Scutella affinis, J. M. t. iv. f. 10, 11. 



Disc circular, mouth very small and central, surrounded by 

 star-like divergent ambulacra ; anus small, placed near the poste- 

 rior margin, apex slightly raised, surrounded by a petaloid star, 

 the pores of which are very fine, and four oviducal holes. 

 Hab. Unknown. As. Soc. Mus. 



The results of the foregoing observations on the natural 

 relations of Echinodermata may be stated as follows : — 

 1. In Asterias the radiated character is most conspicuous 



* This fact must convince us that the growth of these animals cannot depend 

 on the formation of new plates at the apex, since the anambulacral series in this 

 species does not reach to that situation. 



