30 



and puncta. On each side of the shell, are several gradually rising pro- 

 minences ; from which pass, in different directions, several intercurrent 

 lines, on which minute granular tubercles are very thinly disposed ; 

 whilst the general surface is covered with tubercles of rather a larger 

 size. The mouth is small, and nearly round, according to Leske : its 

 situation is, however, not pointed out, nor am I able to point out its 

 situation in either of the three specimens which I possess. The anus is 

 round, and placed in the upper margin of the narrower, and apparently 

 truncated termination of the shell. 



From some peculiarity of structure of this shell, the specimens are 

 almost always distorted. Such is the case with all the specimens which 

 I have seen, and with most of the representations of them. The recent 

 shell is figured with its spines, in the sixth volume of Encyclopedic Fran- 

 fois, PL LIX. Fig. 4. The fossil is mentioned and figured by many 

 authors, but none of the figures appear to exceed those of Scilla. The 

 specimen figured in the present work, Plate III. Fig. 12, is from Malta. 



Spatangus pusillus, Tab. xxiv. c. d. e. Klein, et Tab. xxxvin. Fig. 5, 

 chiefly distinguished by a deep dorsal groove, has not, I conjecture, 

 been yet discovered fossil. 



Spatangus radiatus. This species is only found in a fossil state. The 

 shell is of an ovate circumference, and of a vaulted galeated form. 

 The vertex is pierced with four foramina, 'where four transversely 

 striated and biporous ambulacra arise. Two of these pass nearly half 

 way down the shell, obliquely directed on each side of the posterior 

 part : a dorsal lacuna also, in which are two double rows of pores, ori- 

 ginates from the vertex, and, passing down the anterior part of the 

 shell, is extended to the mouth. The shell is formed chiefly of penta- 

 gonal assulae. The mouth, which is situated in an oblong pit, in the 

 broader and anterior part of the base, is reniform, and beset with pores 

 and tubercula, disposed in somewhat of a stellular form. The anus, 

 which is nearly round, is placed in a pit at the posterior part, close 



