354 LOWER INVERTEBRATES. 



tacles. At its extremity is the large buccal mass, which can be protruded so as to 

 bring the well-developed lingual ribbon, with its sharp and movable teeth, against its 



Fia. iSS. — Atlanta peronii ; a, brain; 6, infra-(ESophageal ganglia; c, eye; 17, gills; 7i, lieart; 

 k, kidney; (, liver; m, mouth; o, ovary; p, operculum; t, male reproductive gland. 



prey. The general positions and relations of the viscera can be seen from our figures, 

 arid need not be described at length. Gills are usually present, but not constantly so, 

 occasionally individuals of the same species varying in this respect. 



The sexes are separate in the heteropods. The eggs are usually laid in long 

 cylindrical cords, which in the case of Firoloides soon break up into short pieces. In 

 the AtlantidiE, on the other hand, the eggs ai"e deposited separately. The young, in 

 their development, pass through a trochosphere and then a veliger stage. 



All of the heteropods ai-e predatory animals, feeding on the numerous forms 

 around them. In seizing their prey, the buccal mass and lingual ribbon are extended, 

 and the lateral teeth are bent outwards; then by a muscular movement the curved 



Fig. 464. — Carinaria. 



laterals are closed against each other, forceps-like, and the prey is secured. The ani- 

 mals are very ravenous, and in their world they play no inconspicuous part in the 

 reduction of the numbers of other animals. Comparatively few naturalists have 

 studied the habits of these beautiful animals, except those found in the Mediterra- 

 nean, and we therefore copy, sometimes word for word, the account given by Mr. 

 Arthur Adams: — Among the pelagic heteropodous molluscs which we found in cross- 



