432 



PROF. F.J. BELL ON THE ECHINOMETRID^. [Mar. 15, 



geographical distribution of the species than it has had hitherto ; 

 for the two specimens are both reported to have come from the 

 island of Mauritius, whence the other species (P. indiana) has (as it 

 seems) been already obtained ; and the only locality for P. granulata 

 hitherto recorded is that of the Sandwich Islands. P. indiana has 

 been received from 



(a) Masbate, 



(6) Philippine Islands, 



(c) Zamboanga (coll. Challenger), 



(e?) Port Lincoln, Torres Straits. 



I do not find myself able to agree with the view according to 

 which we should regard Pseudoboletia as standing in subgeneric 

 dependence to Strongylocentrotus. It seems to me that, as defined 

 by Prof. Troschel, it has the most distinct characters ; the constant 

 possession of four pairs of pores, the deep gill-fissures and large gills, 

 the constant abutting of two ocular plates on the anal region, the 

 very considerable size of the lantern of Aristotle, are certainly 

 enough characters which can hardly be subordinated to the form in 

 which variability in the number of pores is found even in individual 

 specimens, in which the gill-cuts are always slight, in which no 

 ocular plate, or only one, may touch the anal area, and in which the 

 buccal apparatus does not attain to any specially large size. 



But I need hardly attack this " man of straw ;" for although Prof. 

 Alex. Agassiz does technically regard it as a subgenus, yet he (p. 455) 

 speaks of it as a genus, and regards it as intermediate between the 

 Echinometradse and ^he Echinidae. 



The size of the buccal apparatus is very remarkable : in two speci- 

 mens of P. indiana, which had the test respectively 32 and 25 

 millim. high, the height of the lantern of Aristotle was 26 and 22 

 millim. respectively. If similar results should be obtained with 

 P. granulata, it will be necessary to introduce the character into 

 the diagnosis of the genus, and to examine into the extent of its 

 aflSnity to Heterocentrotus. 



Pseudoboletia granulata. 



