120 MANUAL OF NATURAL HISTORY. 



5. FAMILY. Squids (Loliginidee). Eyes simple, co- 



vered with skin ; ears with a transverse crest ; 

 buccal membrane often with cups ; mantle 

 with three internal cartilages, one dorsal two 

 ventral ; tentacular arms partially retractile ; 

 fins on sides of hind part of back. 



II. SUB-ORDER. SEHOPHORES (Sepiophora). 



Shell cellular, calcareous, back hard ; cavity filled 

 with laminae, separated by numerous cells. 



6. FAMILY. Cuttles (Sepiidse). Head united to 



mantle by a broad cervical band ; eyes co- 

 vered with the skin ; mantle with two carti- 

 laginous ridges on ventral side ; tentacular 

 arms* expanded at the end, entirely retrac- 

 tile ; buccal membrane without cups ; si- 

 phuncle with an internal valve. 



III. SUB-ORDER. BELEMNOPHORES (Belemnophora). 



Shell calcareous, internal, chambered; chamber 

 traversed by a siphon. 



7. FAMILY. Spirulas (Spirulidse). Eyes covered 



with the skin, lower eye-lid distinct ; mantle 

 free all round, a linear cartilage on inner side 

 of ventral surface ; body sub-cylindrical, 

 rounded at the end ; buccal membrane with- 

 out cups; sessile arms triangular, with six 

 rows of small peduncled cups tentacular 

 arms elongate, cylindrical, club ? siphuncle 

 with an apical valve ; shell internal, shelly, 

 spiral, chambered ; chambers with a siphon. 

 Pelagic. 



