390 



DECAPODA 



tentacular arms with four ; fourtli left arm hectoeotylised at the 

 tip ; funnel attaclied to the head. Other genera are Loliguncida, 

 Sepioteutliis, and L(i/iolus. Bphmnosrpia, Belotcuthis, Leptotcv- 

 this, and rjtyllofrtiihis ai'c fossil genera, f^iily* differing in the 

 shape of tlie giadius. 



(Ji) Oir/oj^sidae : cornea more or less ojicn ; sjjeeies jjehif/ic. 



Fa:m. 5. Oiiviiiastre.p>Mdac. — 15ody cylindrical, fins generally 

 terminal, united together, regularly rhomhoidal, sessile arms with 

 varying number of rows of acetahula, mantle connexions ehilio- 

 rate ; giadius horny, narrow" lanceolate, witli a liollow cone at 

 the posterior end. — World-wide. 



Ommasf replies proper has a natatory wel) on the sessile arms; 

 the wrist of each club has a series of acetabula with correspond- 

 ing cushions on the other wrist. In IViysanotenfJiis (often made 

 a separate family) the sessile arms have two rows of cirrhi, with 

 lateral expansions of the skin ; fins as long as the body. In 



Fk;. 2.50. — Airhiteuthis princeps, Verr., E. America:/, Riglit fin ; /«, funnel ; /ic, 

 fixing cushion.s and acetabula on the tentacular arms {t, t). (After Verrill. x J^. ) 



ArcliiteutJiis, to which belong the largest Cephalopoda known, 

 the fins together are shaped like a broad arrow-head ; acetabula 

 of sessile arms strongly denticulate ; tentacular arms very long, 

 witli ecpiidistant pairs of acetabula and fixing cushions through- 

 out tlieir entire length, and a group of the same at the base of 

 tlie dull. The acetaliula and cushions correspond on the oppos- 

 ing tentacles, and enaljle them to pull together. Other genera 

 are Dosidicus, Todcirodes, Illex, Bathy ten this and Meistigoteuthis. 



Fam. 6. Onyelioteuthidae. — Body cylindrical, fins terminal or 

 lateral, mantle-locking apparatus elaborate, tentacular arms very 

 long, sessile or tentacular arms furnished with retractile hooks, 

 giadius lanceolate, with a terminal cone. — -World-wide. 



Tlie prehensile apparatus of Cephalopoda reaches its maximum 

 of i)ower and singularity in this family. In Onyehia, Onycho- 



