ROSY HEART-URCHIN. 195 



convex. It is thickly clothed with long curved spines, di- 

 rected as is usual in the tribe. The spines of the post- 

 oral space have wide bent spoon-shaped tips. On the 

 back are seen the four lateral ambulacra, approximating 

 much more nearly at their origins than they do in the 

 common Heart-Urchin. Within them is the dorsal im- 

 pression, shaped like an escutcheon, bearing many promi- 

 nent spiniferous tubercles. Near its posterior extremity 

 are seen the ovarian holes, two of them placed close to- 

 gether, two diverging. The ambulacra are not so wide at 

 their origins as in the last species, and the pairs of pores 

 are not placed in such deep grooves. In the two anterior 

 ambulacra there are five pairs in the foremost row and 

 ten in the hindermost. In the posterior the numbers are 

 equal, nine in each series. The pores of the central am- 

 bulacra are nearly obsolete, and are placed in a single 

 row on each side of the suture, distant and alternate. 

 The tubercles on the anterior portion of the body are 

 largest. The anal impression is circular. The sub-anal is 

 somewhat cordiform, and there are two pores on each 

 side of the space it incloses. That portion of the back 

 between the dorsal impression and the posterior extremity 

 is much wider and not nearly so prominent as the same 

 part in the last species. On the under surface the post- 

 oral spinous space is lanceolate, and slightly carinated 

 throughout its length. The projecting lip over the mouth 

 is nearly straight. The largest specimen which I have 

 seen measures one inch and a half in length and one and 

 a quarter in breadth, and is eight-tenths high. 



The AmpMdotus roseus was first found by Dr. Fleming 

 in Zetland in 1809. Dr. Coldstream afterwards found it 

 twice on Leith sands. During the winter of 1840, I met 

 with a dead specimen on the sandy shore at St. Andrew's ; 



