CEPHALOPODA. 77 



Shelly mucro (oiily known) chambered and siphuncled; \\dnged externally. 

 Fossil, 2 sp. Eocene. Pai'is ; Bracldesham 



Belemnosis, Edwards. 

 Type, B. anomalus, Shy. sp. Eocene. Highgate (unique.) 

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

 gated beak. 



FAMILY Vr. Spirulid^. 

 Shell entirely nacreous ; discoidal ; whirls separate, chambered {polythala- 

 mous^ with a ventral siphuncle. 



Spirula, Lam,, 1801. 



Syn., htuus. Gray. 



Ex., S. la;vis (Gray.) PI. I., fig. 9. 



Body oblong, -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. Eunnel valved. 



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

 spire towards 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 dehcate shell of the spirnla is scattered by thousands on the shores of 

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

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

 Cornwall. But the animal is only knowTi by a few fi-agments, and one perfect 

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



Distr., 3 sp. All the warmer seas. 



ORDER II. Tetkabranchiata. 



Aiiimal creeping ; protected by an external shell. 



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

 caiious. Arms very numerous. Body attached to the shell ])y adductor mus- 

 cles, and by a continuous horny girdle. Branchice fom*. Funnel formed by 

 the folding of a muscular lobe. 



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

 layers and septa nacreous ; outer layers porcellanous.* 



It was long ago remarked by Dill\\7nn, that sheUs of the carnivorous gas- 

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

 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 fossU species belonging to this order are now known by their 

 shells ; whilst their only living representative is the nautilus pompilius, 



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

 shell, relieved by the pearly ground beneath. 



