THE CYLICHNA. 



41 1 



IN both these species, and in all that belong to the same genus, the foot is squared, 

 the head is furnished with a large disc, blunted in front, and divided into two lobes 

 behind. The eyes are never of great size, and in many species are altogether wanting. 

 The organ called the gizzard is furnished with three plates of hard chalky matter, in 

 form somewhat resembling the plates from the back of a chiton, and thought to 

 answer the purpose of teeth. 



ON the top of the engraving is shown a closely allied species, formerly placed in 

 the same genus, but now separated on account of several structural differences. The 

 APLUSTRUM has a shell rounded and slightly colored, but small in proportion to the 



BUBBLE-SHELL. Aplustrum.* 



WOODY BUBBLE-SHELL. Bulla llgnaria. LOBldER. Loblger Phlllpptl. 



BUBBLE-SHELL. Bulla ampulla. BOATMAN-SHELL. Philtne aperta. (Empty shell below.) 



CYLlCHNA.-C>//cAms cyllnriracea. 

 HATCHET-SMHLI Dolabella Kumphll. 



size of the animal. The foot of the Aplustrum is exceedingly large, capable of conceal- 

 ing the shell entirely in its folds. Behind the tentacles are four large and flattened 

 lobes, and the eyes are very small and set at the inner bases of the tentacles. 



A VERY curious creature is seen nearly in the centre of the engraving, lying hori- 

 zontally below the empty shell of the Bulla Ampulla. 



This is an example of a genus termed CYLICHNA : it is remarkable for one or two 

 peculiarities. The animal is smaller in proportion than is generally the case with this 

 family, being short and broad ; and not able to wrap its lobes over the shell. The head 



