CILAP. IV. ] THE CRUISES OF THE ‘ PORCUPINE’ Love 
rows of tube feet, its spines, and five sharp blue teeth ; 
and curious undulations were passing through its 
perfectly flexible Jeather-like test. I had to summon 
up some resolution before taking the weird little 
monster in my hand, and congratulating myself on 
the most interesting addition to my favourite family 
which had been made for many a day. 
Calveria hystrix—for I have named this genus and 
species after our excellent Commander and his tidy 
Fie. 28.—Calveria hystrix, WyvILLE THomson. Inner surface of a portion of the test showing 
the structure of the ambulacral and interambulacral areas. 
little vessel, in grateful commemoration of the plea- 
sant times we had together —is circular and depressed, 
rather more than 120 mm. in diameter, and about 
25 mm. high (Fig. 28). Both interambulacral and 
ambulacral areas are wide. The peristome and the 
periproct are unusually large ; the former covered with 
calcareous scale-like plates, perforated up to the rim of 
the mouth for the passage of ambulacral tube-feet, as 
in Cidaris ; the latter with a large madreporic tubercle 
