PKiKSTIVK OIKIANS. .'Jl 



sL'jKinitud ill lliu Ciiliuuaiics, in Se-piii unci iScpiuhi ; if«s lung but 

 well seiKimtcd in Omnitistre[)lu'S ; but little sepanited in Onyclio- 

 teuthis, in Loligoiisis and in Ilistioteuthis, which at the same 

 time have a much longer, mure curved and sharper rostrum. The 

 posterior expansion is short, composed of three equal lobes in 

 the Argonauts and Tremoctopus, very long and with only an 

 indication of a lobe in Octopus, and without lobes in Sepia, the 

 Calamaries, Rossia and all other cephalopods. 



The rostral part of the inferior mandible is rounded behind in 

 all the octopods, slanting in the decapods. The wings are short, 

 wide in Aigonauta and Tremoctoi)us ; very long, narrow and 

 arcuated in Octoi)us ; long, straight and wide in Sepia, etc.; 

 short in Onychoteuthis and Ommastrephes. The posterior ex- 

 pansion is wide, not carinated above in Argonauta and Trem- 

 octopus ; very long, narrow, carinated in Octopus ; moderately 

 long, wide, carinated above, more sloped in Sepia, Sepiola and 

 the Calamaries; very short much carinated, strongl}- sloped be- 

 hind in Onychoteuthis, Ommastrephes, etc. 



Under the tongue is found a fleshy mass covered with pa})illft', 

 which is supposed to be the organ of taste ; and in Nautilus we 

 find similar papilla; on the tongue (behind the teeth), to its 

 entrance into the gullet. 



The fleshy tongue is tinned above with rows of recurved, 

 spinous teeth, the arrangement of which dilTers in the various 

 genera. Ordinarily, as in the dibranchiates, we lind the series 

 of teeth to consist each of a central one with three side-teeth on 

 either side of it, and sometimes, as in p]ledone and Loligo, an 

 additional plate on either side ; but in Nautilus we And a modi- 

 fication in five somewhat quadrangular central teeth of which the 

 middle one has the most pointed end, and on either side two 

 long fangs Avith a much smaller plate at the base of each — in all 

 thirteen teeth in a series. The central teeth, which are simple in 

 Sejua and Sepiola, are tricuspid in Loligo and denticulated in 

 Eledone ; Avhilst the lateral uncini are usually claw-like. Fifty 

 rows of teeth may be found on the tongue of the Sepia ; their 

 continuous growth comi)ensates the loss by abrasion. 



(Plates 5 and G exhibit the teeth of various cephalopods.) 



The rounded, sack-like stomach which is situated towards the 

 middle or end of the body is connected with the mouth by a long 



