ECHINODERMATA. 



tive position of the parts, are better exposed when the shell is stripped of 

 the numerous spines and bristles by which, like the preceding species, it 

 is almost totally covered. Convex surface, fig. 15 ; flattened surface, 

 fig. 16. 



About fifty suckers, issuing from pores of the shell, are scattered, 

 without any definite arrangement, over the other parts, chiefly towards 

 the mouth. They are void of resemblance to those either of the Echinus, 

 or any other animal with which I am acquainted. Each .is a crimson 

 flower or flattened disc, expanding an eighth of an inch, supported by 

 a stem a quarter of an inch high. The margin of the flower is beset by 

 a border of cylindrical prolongations. Plate XXXII. figs. 13, 14. 



Both the animals thus obtained seemed to be casting their spines, 

 whereof the older, extending nine or ten lines, were dingy yellow ; the 

 new ones very short. Those of a small specimen, one under an inch in 

 diameter, were of the same character on the first of March. 



At this time another Spatangus purpureus was invested by a thick 

 coating of the shortest spines. 



From the occurrence of more, of similar description, the spines are 

 probably renovated about the commencement of the year. 



As previously signified, I am no stranger to what is said al primary 

 and secondary spines on the same animal. But, without entering fur- 

 ther on the subject, the real source of the discrepance between them, 

 must be sought, perhaps, in the progress of age, or of reproduction. 



Undoubtedly spines of different character may invest different parts 

 of the same specimen, as is seen of nails, horns, hair, and feathers. 

 Very minute tubercles, on different parts of the Spatangus, may bear, 

 cither peculiar spines, or those in progress. 



When the shell is quite divested of its covering, a stellate figure of 

 five rays appears on the convex side, four of which are formed by a 

 double row of pores, the fifth being merely a hollow or depression. Four 

 apertures, said to be the ovarian pores, and sometimes a greater number, 

 occupy the middle of this stellate figure. 



The mouth is situated amidst a less definite stellate form, in the 

 opposite or flattened side of the shell. The figure of a long shield, com- 



