28 



19. Histioteuthis, D'Orbigny, 1839 Arms, with the exception of two united 



by a membrane, with two rows of 

 suckers on stalks ; tentacles with six 

 rows of stalked cups having a dentated 

 margin ; pen short and broad. 



II. Eyes covered by a transparent membrane, Myopsidas. 

 (D'Orbigny, 1841). 



VI. — Group of the eye-covered Cuttles having a horny internal shell without 

 a head band. Mantle strengthened by ridges and grooves. Fins 

 generally terminal. Head as wide as the body. Arms with two 

 or four rows of suckers. Funnel generally valved. Gonatidse. 

 Four genera, Loligo, Gonatus, Rossia, and Sepioteuthis. 



20. Loligo, Lamarck, 1799 



21. Gonatus, Gray, 1849 



22. Rossia, Owen, 1835 



= Heteroteuthis, Gray, 1849. 



23. Sepioteuthis, Fe'russac, 1825 



= Chondrosepia, Leuckart, 1828. 



Body long, conical ; fins terminal, tri- 

 angular ; arms with two rows of suckers, 

 tentacles with four ; pen long, lanceo- 

 late, multiplied in number by age. 



Body long, conical ; fins terminal, trian- 

 gular ; arms with four rows of suckers ; 

 tentacles with many rows of small 

 suckers, and a larger one with a hook at 

 the base ; no valve ; pen lanceolate. 



Body somewhat short, cylindrical ; fins 

 terminal, somewhat triangular ; arms 

 webbed at the base, suckers irregularly 

 disposed in two or four rows ; tentacles 

 completely retractile, with irregularly 

 arranged suckers ; pen small, lanceolate. 



Body somewhat oval ; fins lateral, as long 

 as the body ; arms short, with two rows 

 of suckers; tentacles partly retractile, 

 with four rows of suckers ; pen horny, 

 long, lanceolate, strengthened by a 

 strong middle rib. 



Division B. — Of the horny shelled Cuttles, Teuthidse, having the mantle 

 united by a band to the head, with eyes naked or the reverse. 



VII. — /. Eyes naked, without a covering membrane, Oigopsidse (D'Orb.) 

 Loligopsidae (Gray, 1840). One genus, Loligopsis. 



24. Loligopsis, Lamarck, 1812 



=Leachia, Lesueur, 1821. 

 = Perothis, Eschscholtz, 1827. 



Body elongate ; mantle supported by one 

 dorsal, and two ventral muscular bands ; 

 fins terminal, curved ; arms with two 

 series of suckers on stems, and with 

 horny margins ; tentacles not retractile, 

 slender, with scattered suckers; pen 

 slender, lanceolate, with a minute conical 

 appendix. 



VIII.—//. Eyes covered by a transparent membrane (Myopsidse). Fidenidae. 

 Four genera, Sepiola, Sepioloidea, Fidenas, Cranchia. 



