124 A Guide to the Zoological Collections in tJie 



slender, polished and acutely pointed, and consist of a 

 spiral of many whorls. 



gth Family, Pjeurotomidae [Cases 157 A-B]. 

 The " Hare-lip shells " although universally distributed 

 are most numerous in tropical seas. About eighty s[)ecies 

 are also known from depths of 200 to 2,500 fathoms. In 

 the typical forms the shell has a long channel for the 

 siphon, and is deeply cleft in the outer lip near the 

 " suture", the mantle also having a corresponding cleft. 



loth Family, Cancel faridse [Case 157B]. 



In this family also the majority of the species inhabit 

 the seas of the tropics. The shell is "cancellated", or 

 marked with a fine lattice-work of cross-ribs. The animals 

 are said to be vegetarian. 



nth Family, Muricidse [Cases 157C— 160A]. 



This is a very large family, the constituent species of 

 which are widely distributed, though most abundant in 

 warm and tropical seas. The shells are often beautifully 

 and regularly " variced " or ribbed, the ribs being some- 

 times foliated and frilled and sometimes ornamented with 

 rows of long spines. In the animal, an adrectal gland is 

 highly developed and secretes a colourless fluid, which, on 

 exposure to the air, turns purple ; and it was from a spe- 

 cies of Murex that the famous Tyrian purple was manu- 

 factured. 



i2th Family, Bucclnidse [Cases 160A — 162B]. 



The type genus of this large family — the Common 

 Whelk [Buccinum) — \s confined to the colder temperate 

 and the polar seas ; but several of the largest genera — e.g., 

 Nassa, Purpura, Ricinula — occur in great abundance in 

 Indian waters. The shells vary greatly in form ; in many 

 species they have a large and well-produced spire, but in 

 some genera — e.g., Purpura, Ricinula, Cuma, Rapana — 

 the spire is short, being sunk in the last whorl, which is 

 very large. The species of Purpura secrete a purple dye. 



