TOXOPNEUSTES. 297 



Echinus norvegicus and referred the single small specimen to Echinus 

 Flemingii. It is a young Echinus norvegicus of which the Museum now 

 possesses a good set of specimens, thanks to Professors Thomson and Loven 

 and Dr. Lutken. 



The younger Sars has separated as distinct from E. norvegicus, under the 

 name of E. rarispinus, specimens which are in my opinion only very globular 

 E. norvegicus ; under the name of E. depressus, large flattened specimens with 

 remarkably large and stout spines of an umber color, tipped with pink, equal- 

 ling in length more than half the diameter of the test, with a somewhat 

 larger anal system, more like that of E. elegans, and in which the second- 

 aries are arranged in circles round the primaries upon the somewhat higher 

 coronal plates. The series of specimens dredged by the Porcupine Expedi- 

 tion plainly shows this to be a modification of the typical E. norvegicus, 

 which previously had been known mainly from small specimens, very few 

 of them measuring more than one to one and a half inches in diameter 

 having been found previously. 



TOXOPNEUSTES. 



Toxopneustes Agass. 1836. Prod, (non Agass. Des. 1846). 



Ecnini with test more or less conical, tubercles of uniform size, arranged in 

 several vertical rows in interambulacral and ambulacral spaces. Poriferous 

 zone broad, pores arranged in inclined arcs of three pairs, in the larger spe- 

 cies forming three irregular vertical rows resembling the arrangement of 

 Hipponoe. The actinostome is large, the cuts are deep, the buccal mem- 

 brane thickly plated with large imbricating plates. Spines short, moder- 

 ately stout. 



My attention was first called to the affinity of Boletia and Lytechinus 

 from a comparison of young Boletia pileolus and Boletia rosea with young- 

 specimens of Lytechinus ; the former had all the features of Lytechinus, 

 except of the plated buccal membrane. A closer examination of the sub- 

 ject shows that no positive character can be drawn to distinguish the two 

 genera except the presence of the plated buccal membrane of Lytechinus. 

 The peculiar pedicellarige so finely developed in Boletia also occur in Lyte- 

 chinus, but are much less numerous and also much smaller. The structure 

 of the abactinal and actinal systems, the general structure of the ambulacral 



