6236 



Marine Aquarium. 



Eolis papillosa creeps very quickly, and is lively in its habits. It 

 is fond of squeezing its flaccid body into crevices and narrow places. 

 I have fed it with anemones. One, two and a half inches, ate 

 every week an Actinoloba Dianthus about an inch in diameter. 

 The tube on the right side of the body can be exserted to some 

 length. 



Cylichna obtusa. These animals live in sand, moving about slowly, 

 with the head, disk and fore part of the shell buried, and leaving a 

 very distinct trail. They feed on Hydrobia?, which abound on the 

 sand-banks where the Cylichnse are found. They can crawl on glass 

 and stone as well as through the sand, but the least obstacle causes 

 them to lose their hold and fall. They progress by pushing forward 

 the foot, and then drawing the shell after it. Unlike the larger 

 species of the same genus, the tongue seems to be unarmed. I have 

 not found them do well in aquaria. 



Chitons live well in confinement. It is not known exactly what 

 Ihey feed upon, but I have noticed the common Chiton scrape the 

 glass like a periwinkle. The appearance of the tongue when in 

 action is very peculiar, resembling the opening and closing of a fan. 

 They creep about freely, but their motion is slow. A small specimen 

 of Chiton cinereus, nearly white, has not grown during a year's con- 

 finement. Mollusca very frequently become stunted in aquaria, from 

 want of sufficient nourishment. It is very frequently the case with 

 fresh-water snails, which sometimes also become distorted. 



Bivalves are less interesting than univalves in aquaria ; an accu- 

 rate examination of a bivalve, moreover, cannot be made without 

 destroying, to observe, the branchiae and palpi. They generally live 

 very well, and as they require no feeding they are very little trouble 

 to keep. Some require a deep bottom of fine sand, and others do 

 well in an ordinary tank. 



The oyster is one of the latter class, and, as it is probably the 

 hardiest of bivalves, it is very suitable for keeping an ordinary tank 

 free from the spores of the weeds, — a service for which the presence 

 of some Acephalee is indispensable. Mussels may be used for the 

 same purpose, and if handsome specimens are selected they are more 

 ornamental than oysters, though not so hardy. Young mussels are 

 often abundant on whelk. The siphonal apertures are at first plain- 

 margined, and, in the very young, ciliate ; the branchial one after- 

 wards becomes laciniate, and as they advance in age the laciniations 

 become more and more complicated. The mantle is more protruded 

 than in the adult, and the terminal character of the umbone less 



