465 



a membranaceous nature, is obferved, which frequent- 

 ly (hoots into fpines of the fame texture. 



This circumftance is not fo common, and feems to 

 depend either on age, or on the water it inhabits : in 

 fome. places it is found only of a light, pellucid horn- 

 colour ; in others always dark-brown. It is fubjeft alfo 

 to fome variation in the aperture ; this, however, is 

 generally round, not interrupted by the volution ; 

 fometimes, indeed, it projefts, and does not adhere ; 

 othe s clafp the body whirl a little, and are fomewhat 

 comprefTed into a fub-oval. Thefe laft muft be confi- 

 dered as mere varieties. It is diflinguifhed at once by 

 the diftant annulations, though not always confpicuous 

 without being confiderably magnified. Thefe varieties 

 had induced Mr. Walker to make them into two dif- 

 tin61 fpecies. 



LiNN.EUs, in the tenth edition of his Svjlevia Natu- 

 rcE, had made it a Nautilus under the title o[CriJia, and 

 afterwards removed it into the Turbo genus. In this re- 

 fpeft we have deviated from that great naturalift, by 

 making all the depreffed fhells HHices, without regard 

 to the mouth ; a charafter in itfelf extremely vague, 

 though perhaps it will be very difficult to find a better, 

 for the divifion of the two genera fo nearly connefted. 



We originally received fcveral of thefe fliells from our 

 friend Mr. Boys, for thofe o£ the r,t,inufarariora, who 



O o o obferved, 



