318 CARNIVOROUS MOLLUSCA. 



and the study of the apparatus by which the hold is given, 

 has suggested to the ingenious Professor Simpson (a name 

 now very dear to humanity) an instrument that may do away 

 with the use of others often hurtful in unskilled hands and 

 difficult of application. To substitute a safe power for the 

 accoucheur's forceps was the professor's worthy object, and 

 he writes me, — " After great battling and bafliing, I looked 

 at last at the form of nature's suckers in the cuttle-fish. 

 I found they were double cups, and, in imitating this, I 

 immediately got a small caoutchouc sucker made, capable of 

 pulling thirty or forty pounds, which is far more than is 

 required by the forceps in nineteen cases out of twenty." * 



There are two tribes of cotyligerous or dibranchiate 

 Cephalopods, — the octopods and decapods. -j- The prehen- 

 sile organs of the former are, as the name indicates, eight 

 in number, all of the same kind, developed from the mus- 

 cular cone enclosing the apparatus of the mouth, and in 

 general very long proportionably to their short rounded 

 bodies. Their suckers are arranged in one or two rows 

 along the oral aspect, diminishing in size by insensible gra- 

 dations until they become almost invisible at the tapered 

 gracile extremities ; and there are numerous similar suckers 

 scattered over the membrane that covers the mandibles. 

 The limb of these suckei's is flat and soft, but marked with 

 striae or furrows which radiate from their hollow centre, 

 and may oppose an obstacle to their gliding over a slimy 

 surface. The decapod cuttles have eight analogous arms 

 or feet, but they are always greatly shorter, — a fact which 

 is the more remarkable since the body in this tribe is usually 

 lengthened and pointed below ; and you might not unrea- 

 sonably imagine that as they are swimmers, roaming at large 

 in the wide ocean, and living on agile prey, a great length 

 of arms was the more necessary to them. 'Tis very true ; 

 and to remedy this seeming defect, there has been given two 

 long additional tentacula, nearly similar in structure to the 

 arms but more pliant, and, like them, armed with cups 

 either along their whole line, or more commonly only at 



* See also Monthly Joiini. Med. Science for Feb. 1849. 



f I here employ, as throughout the work, the usual nomenclature of con- 

 chologists, hut strictly speaking, "all the naked Cephalopods are octopods, 

 the disk which produces these feet by its division, never producing a greater 

 number than eight ; but in many genera, two retractile pedunculated tenta- 

 cula are developed, and extend from within this outer subdivided disk, and 

 generally between the first and second anterior arms on each side, which has 

 given rise to the division termed Decapodu in this class. The tentacula, 

 however, never assume the form of the other feet." — Grant in Trans. Zool. 

 Soc. i. 21. 



