292 BEAUTIFUL MOLI.USKS. 



aperture of their stolen habitaculura. On being captured, 

 they always retreat to the further end of the shell. 



On the little Island of Ibugos, one of the Bashee Group, 

 I had the pleasure of observing the large and hand- 

 some Pleurobranchus testudinarius, figured in Philippi's 

 ' Enumeratio Molluscorum Sicilise ' (Tab. XX. Fig. 1.), in 

 its native element. It was gliding quietly along, at the 

 bottom of a shallow salt-water pool, near the shore. The 

 cheloniform back of the animal is splendidly variegated 

 with various rich and glowing colours, chiefly ruddy 

 browns, Vandyke, Sienna, and Bistre, with Lake and 

 Indian yellow, relieved by numerous dead white specks. 

 The integument is covered with hexagonal markings, 

 which each rise to a central nucleus, giving to the 

 creature, when in motion, very much the appearance of 

 a diminutive Tortoise. The branchial organs, beautifully 

 lamellated. are arranged in two rows ; they are placed in 

 the body-groove of the right side, just above the foot, and 

 are slightly protruded beyond the margin of the mantle. 

 The belly is of a dark slate colour, the gills are purplish, 

 and the appendages of the head of a rich red -brown. In 

 its movements, this Mollusk is slow and deliberate, 

 crawling in a slug-like manner, at the bottom of the 

 water. The chromatogenous vesicles, or cytoblasts of 

 colouring matter, when examined microscopically, were 

 found very large, and well-developed in the soft, coloured 

 skin of this beautiful Mollusk. 



On the same flat, weedy beach, there is a peculiar 

 species of Cattianassa, which digs pits in the sand, in the 

 manner of the Ant-Lion. It is a long, red-coloured 



