HABITS AND ECONOMY OF THE MOLLUSCA. 141 



Reptiles furnish a few destroyers of molhisks. Tlius the 

 tortoises of our gardens eat snails, and it is common to put these 

 animals in a cellar infested with slugs in order to exterminate 

 them; the toad eats both snails and Helices ; the frog and water- 

 lizard eat the fresh-water snails ; the Pseudopus, of our 

 menageries, eats snails only. 



In their own element, marine mollusks are perpetually devoured 

 by fishes. The haddock is a " great conchologist ;" and some 

 rare northern shells (Grlj^cimeris, Buccinum, Neptunea), have 

 been rescued unbroken from the stomach of a cod. (One of them 

 furnished thirty-five to forty shells of Buccinum undatum.) 

 Hyndman has estimated at 35,000 the mass of a small bivalve 

 shell ( Turtonia minuta) found in the stomach of a mullet 

 (Jelfreys). Some fishes break the most solid shells ; thus the 

 valves of a Cyprina cannot resist the teeth of the cat-fish (^Anar- 

 hichas lupus). The Octopus, notwithstanding its intelligence, 

 cunning and powers of defense, is very frequently the victim of 

 the Conger Eel, which seizes it in its most secluded retreats. 



The oyster-culturists at Arcachon (France) dread the ray, a 

 fish which attacks young oysters. In one night, fourteen of 

 these fishes destroyed more than 1^0,000 young oysters in a single 

 pare. In the Oostanaula River, Georgia, the drum-fish {Pogonias 

 chromis, L.) crushes the valves of IJnios with its palatal 

 armature in order to eat the soft parts.* 



Articulated animals destroy but few shell-fish. Fischer has 

 seen crabs break the shell of young oysters with their pincers ; 

 Libinia canaliculata^ the common spider-crab of the American 

 coast is very destructive to oyster-beds, and some others of 

 our crabs have probablj' similar habits. Carabus, Georus, 

 Staphilinus, Cychrus and S^dpha, among insects attack terres- 

 trial gastropods. The larva of Drillus Mauritianus detaches 

 with its mandibles the operculum of Gyclostoma mamillare, and 

 undergoes metamorphosis within its shell, after having eaten the 

 rightful proprietor (Lucas). Larval glow-worms also live on 

 Helices, and will eat two or three before passing into the nympha 

 state (Godard). Gochleoctonus vorax lays an egg in the body of 

 dilfereut species of snails ; when hatched, the larva feeds upon 

 its host (Jeffreys). The species of Perthostoma, an American 

 aquatic hemipterous insect, eat large quantities of Limusea, 

 Physa and Planorbis, which they hold with the fore-legs by 

 folding between the thighs and tibiae ; even the larva of this 

 insect, shortly after escaping from the egg, will seize and devour 

 one of these mollusks with as much ease as if schooled in the 

 process a long time (Leidy). Mollusks even fall a prey to animals 

 much their inferiors in sagacity. Thus the star-fish swallows 



*Bull. Ann. Mai. Belgique, xii, 23. 



