CEPHALOPODA. 77 



Shell, mucro (only kno^mi) chambered and siplmnclcd; ^\^nged externally. 

 Fossil, 2 sp. Eocene. Paris ; Bracklesliam 



Belemnosis, Edwai-ds. 

 Type, B. anomalus, Sby. sp. Eocene. Higligate (unique.) 

 Shell, mucro, chambered and siphuncled ; without lateral wings or elon- 

 gated beak. 



FAMILY VI. Spira-LiD.E. 

 /S"//.?// entirely nacreous ; discoidal; w^hirls sepai-ate, chambered {pohjthala- 

 moi.(.s) with a ventral siphuncle. 



Spirula, Lam., 1801. 



Syn., lituus, Gray. 



Ex., S. hcvis (Gray.) PI. I., fig. 9. 



Body o])lon^, with minute terminal fins. Mantle supported by a cervical 

 and 2 ventral ridges and grooves. Arms with 6 rows of very minute cups 

 Tentacles elongated. Funnel valved. 



Shell placed vertically in the posterior part of the body, with the involute 

 spire tow^ards the ventral side. The last chamber is not larger in proportion 

 than the rest ; its margin is organically connected ; it contains the ink-bag. 



The delicate shell of the spiiiJa is scattered by thousands on the shores of 

 New^ Zealand ; it abomids on the Atlantic coasts, and a few specimens are 

 yearly brought by the Gulf-stream, and strewed upon the shores of Devon and 

 ComwalL But the animal is only known by a few fragments, and one perfect 

 specimen, obtained by Mr. Percy Eaii on the coast of New Zealand. 



Bistr., 3 sp. All the warmer seas. 



ORDER 11. Tetrabranchiata. 



Animal creeping ; protected by an external shell. 



Head retractile within the mantle. Eyes pedunculated. Mandibles cal- 

 cajious. Arms very numerous. Body attached to the shell by adductor mus- 

 cles, and by a continuous horny gii-dle. Branchice four. Funnel formed by 

 the folding of a musculai" lobe. 



Shell external, camerated (poly-thalamous) and siphimclcd; the inner 

 layers and septa nacreous ; outer layers porcellanous.* 



It was long ago remarked by DiUwynu, that shcUs of the carnivorous gas- 

 teropods were almost, or altogether, wanting in the palaeozoic and sccondaiy 

 strata ; and that the office of these animals appeared to have been performed, 

 in the ancient seas, by an order of cephalopods, now nearly extinct. Above 

 1,400 fossil species belonging to this order are now known by their 

 shells ; whilst their only living representative is the nardilus jjompihus, 



* The Chinese carve a variety of patterns in the outer opaque layer of the nautilus 

 shell, relieved by the pearly ground beneath. 



