CEPHALOPODA. 77 



Shell, mucro (only known) chambered and siplmncled; winged externally. 

 Fossil, 2 sp. Eocene. Paris ; Bracklesham 



BELEMNOSIS, Edwards. 



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

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

 gated beak. 



FAMILY VI. SPIRULHLE. 



Shell entirely nacreous ; discoidal ; whirls separate, chambered (potytkala- 

 mous^) with a ventral siphuncle. 



SPIRULA, Lam., 1801. 



Syn., h'tuus, Gray. 



Ex., S. leevis (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. Funnel 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 delicate shell of the spirula 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 known by a few fragments, and one perfect 

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



Distr., 3 sp. All the warmer seas. 



ORDER II. TETRABRANCHIATA. 



Animal creeping ; protected by an external shell. 



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

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

 cles, and by a continuous horny girdle. Branchiae four. 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 Dillwynn, that shells of the carnivorous gas- 

 teropods were almost, or altogether, wanting in the palseozoic 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 fossil 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. 



