1S8I.] PROF. F, J. BELL ON THE ECHlNOMETRIDiE. 



Si'HiERECHlNUS GRANULARIS. 



431 



The first seven specimens, coming all from one locality, are very 

 interesting, as exhibiting the range and character of the variations in 

 this eminently variable genus. 



PSEUDOBOLETIA. 



This genus has been so amply defined by Prof. Troschel, that it is 

 only necessary to put his definition into English. "Test flattened 

 and curved, thin ; tubercles small ; four pairs of pores in an arc ; 

 two ocular plates touch the periproct ; rather deep gill-fissures ; 

 auricles with large foramen and low connecting ridge. It is distin- 

 guished from Boletia, Desor, by having four pairs of pores in each 

 arc."^ 



Two species have been described in it — one by Michelin as 

 Indiana, the other by A. Agassiz as Boletia granulata. By the latter 

 author Pseudoboletia is recognized as a subgenus, and P. steaostoma 

 and P. maculata of Troschel are stated to be synonymous with P. 

 granulata and P. indiana respectively. 



There are certainly two species in the British-Museum collection ; 

 and one is just as certainly P. indiana ; the other species is certainly 

 stenostomatous as compared with P. indiana, and even more so 

 than was Prof. Troschei's specimen ; this, of course, may be due to- 

 the fact of its being older. When we study it by the aid of the 

 original definition^ of B. granulata — "remarkable for its compara- 

 tively long spines ; tubercles uniform in size, very closely crowded 

 together," — we are unable to gain any assistance from the first 

 clause, owing to the absence of the spines ; but the second half of the 

 definition applies very well ; and, on the whole, I am inclined to feel 

 certain that the specimens are representatives of P. granulata. If, 

 however, they are so, they give a somewhat different aspect to the 



' The^e speciraens were collected at Naples. 



2 8itzb. uaturh. Yer. preiiss. Rheinl. 1859, p. 96. 



^ 13ull. M. C. Z. i. 2 (1863), p. 24. 



