118 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



drawn up into it when the animal retreats. In some 

 cases there is a lid (the operculum) upon the tail which fits 

 the opening of the shell. The yellow egg-capsules of 

 Purpura are seen at 4a. From 10 to 20 eggs are as a 

 rule laid in each capsule, but of these only one readies 

 maturity and emerges as a young Purpura. That one is 

 in every sense representative of its brothers and sisters, 

 as it has eaten all the rest. Various kinds of periwinkle 

 (Littorina) and the only kind of Cowrie (Cyprcea 

 europea) found in our seas are generally present in the 

 Aquarium. 



The two remaining animals shown in fig. XXI. are 

 Cuttlefishes (Cephalopoda). Xo 5 is the common squid 

 (Loligo vulgaris), with eight short " arms " and two longer 

 " tentacles " attached to the head, and all of them bearing 

 suckers. Loligo has an internal shell shaped like a 

 short Roman sword, and made of a flexible transparent 

 horn-like substance. The remaining Cephalopod (Xo. 6) 

 is a kind of " Octopus " called Eledone cirrosa. It has 

 only the eight sucker-bearing arms, the body is shorter and 

 rounder than in the squid, and there is no shell of any 

 kind, external or internal. This animal is found in many 

 parts of the Irish sea, and is generally on view in our 

 tanks. It differs from the true Octopus (Polypus 

 vulgaris), which has two rows of suckers on its arms, in 

 having one row only, and the ground colour of the body 

 is of a lighter hue than that of the < )ctopus. It is a 

 voracious animal, and feeds when in captivity upon living 

 crabs and crayfish, which it readily devours by means 6i 

 its powerful, horny beak, something like that of a parrot, 

 which is lodged just inside the mouth, the aperture of 

 which forms a sort of centre from which the eight rows 

 of suckers radiate. The pulsating movement seen when 

 the animal is at rest is respiratory. Water is admitted 



