1 72 On Cyrtoma, a new genus of Fossil Echinida. 



radiated extremities, and the dorsal and abdominal regions 

 of the body which are lost in Echini again distinctly cha- 

 racterised. In the Encrinites, or fixed starfish, we find the 

 abdominal region attached to a column for the support of a 

 body, whose limbs as yet rudimentary are only sufficient for 

 the collection of food. In the Comatula and Euryale, of 

 Lamarck, we see a more highly developed system of extre- 

 mities, the abdominal and dorsal regions still better marked, 

 and the body left free without a stem or fixed support. Again 

 our next step introduces us to the Asterias, in which we find 

 the radiated limbs more highly developed and approximated 

 to the structure of the Annulosa. Here the spines which 

 were the only means of defence to the spheroidal body of the 

 Echinus disappear altogether on the abdominal region, or 

 are changed in form, and arranged along the margins of the 

 groove, so as evidently to direct objects into the mouth, thus 

 compensating for the immoveable character of the limbs. 



The grooves on the lower surface of the Asterias indicate 

 the change from the perfectly incased Echinides to the high- 

 er classes, whose intelligence and organization are sufficient 

 to enable them to protect themselves from danger. 



The annulose animals supposed by Mr. MacLeay to come 

 nearest to Echinodermata are the Crustacea, and the osculent 

 group by which the two are united is, he thinks, Cirrhopoda, 

 but I have no materials for the examination of this part 

 of the subject, and unfortunately Calcutta is not well adapted 

 for collecting them without some intelligent and influential 

 friends on the coasts. The Asiatic Society in a late injudici- 

 ous report on the duties of Curator announce, that it is clearly 

 within the scope of their influence to procure within a few 

 months collections of specimens from every part of India. 

 Assuming this to be the case, can any thing be more disgrace- 

 ful than the fact of their collections being almost without a 

 single specimen of any one of the extensive classes of ani- 

 mals now under review ? 



The presence of a nervous system in the Asterias, together 



