52 ZOOLOGY 



is applied to this division of Mollusca is derived from the 

 shape of the fore-foot. The bivalves include all the shellfish 

 known as mussels, clams, scallops, and oysters. Amongst the 

 univalves we reckon the land and sea snails, the periwinkles, 

 whelks, top-shells, and cowries of our shores, whilst the 

 Cephalopoda include the rare tropical Pearly Nautilus 

 the only living form belonging to this group which has a 

 spirally coiled external shell the squid, the calamary, and the 

 octopus which haunts the submarine holes in rocks all round 

 our coasts. To the same group belongs the enormous squid 

 of Nova Scotia, in which the body is ten feet long and the 

 "arms" (i.e. the divisions of the fore-foot) may be 40 feet 

 long. The greater number of the Mollusca are neither 

 harmful nor useful to man, but a few are used for food. The 

 most prized and in every way the most valuable is the oyster 

 a bivalve in which the muscular foot is absent, and which 

 on that account is much more edible than its allies ; but the 

 mussel (Mytilus), the cockle (Cardium), and the scallop 

 (Pecten) are extensively eaten by the poorer classes. In 

 America the hard-shelled clam (Venus mercenaria) and the 

 soft-shelled clam (Myd) are esteemed as delicacies. Amongst 

 univalves , the periwinkle (LiUorina) is the only one which is 

 used for food in this country, but in France the snail is 

 consumed, and is actually bred for consumption since it is 

 regarded as a delicacy. Amongst cuttle-fish the common 

 squid (Sepia), the calamary (Loligo), and the octopus are all 

 used for food in Italy : but the secondary usefulness of 

 Mollusca as bait to capture the valuable edible fish far ex- 

 ceeds their direct value as food. In this country countless 

 thousands of the Limpet (Patella), perhaps our commonest 

 univalve, are used for this purpose. In North America the 

 soft-shelled clam (Mya) and various forms of cuttle-fish 

 (Loligo, Ommastrephes, &c.) are used. The struggle to 

 obtain these valuable forms of bait has already led to inter- 

 national complications between the British Colony of New- 

 foundland and the United States of America and has also led 

 to bad blood between the provinces of the Dominion of 

 Canada, since the people of New Brunswick have accused 

 those of Nova Scotia of ravaging their clam-beds. 



Next to the Mollusca we must devote a few words to the 



