166 



MANUAL OP THE MOLLTTSCA. 



suckers in two rows; tlie tliird left arm nectocotylised at tlie 

 apex. 

 Diatrihution, 2 species. Mediterranean. 



BoLiT^NA. Strp. 1858. 



Similar to Eledone, but more gelatinous, and with small 

 suckers. 1 species Hying. 



Section B. — Decapoda. 



Arms 8. Tentacles 2, elongated, cylindrical, with expanded 

 ends. Suckers pedunculated, armed with a horny ring. Mouth 

 surrounded by a buccal membrane, sometimes lobed and fur- 

 nished with suckers. Eyes movable in their orbits. Body 

 oblong or elongated, always provided with a pair of fins. Funnel 

 usually furnished with an internal valve. Oviduct single. Nida- 

 mentcd gland largely developed. Shell internal ; lodged loosely 

 in the middle of the dorsal aspect of the mantle. 



The arms of the decapods are comparatively shorter than 

 those of the octopods ; the dorsal pair is usually shortest, the 

 ventral longest. The tentacles originate within the circle of 

 the arms, between the third and fourth pairs ; they are usually 

 much longer than the arms, and in cheiroteuthis are six times 

 as long as the animal itself. They are completely retractile 

 into large subocular pouches in sepia, sepiola, and rossia ; partly 

 retractile in loligo and sepioteuthis ; non-retractile in cheiroteuthis. 

 They serve to seize prey which may be beyond the reach of the 

 ordinary arms, or to moor the animal in safety during the 

 agitation of a stormy sea. 



The lingual dentition of the cuttle-fishes somewhat resembles 

 that of the ptercooda. The central teeth are simple in sepia and 



Fig. 39. Lingual teeth of Sepia officinalis (Cockeii). 



sepiola^ tricuspid in loligo, and denticulated in eledone. The 

 lateral teeth or uncini are three on each side, and mostly simple 

 and claw-like. There were fifty rows of teeth in one specimen 

 of sepm, the ribbon increasing in breadth from before to behind. 



