42 LINNEAN GENERA. 



Nautilus spirula. — The Spiral Nautilus. Plate III. fig. 11. 

 (Spirula Peronii, Lamarck.) Aperture of the shell orbicular; 

 whorls cylindrical, separated, and gradually decreasing inwards, 

 the first a little straight ; siphunculus contiguous to the walls of 

 the shell ; outside of a pale cream colour, pearlaceous within. 



Inhabits the American and Indian oceans. 



V Siphunculus, w w w w w chambers. 



The curious structure of the shell of the Nautilus Pompilins, (which 

 also runs, with some variation, through the whole genus,) cannot Wfe con- 

 templated without admiration, each cell or camera communicating with the 

 next by a small and short tube, the first or principal cell being far larger 

 than the rest, and appearing destined to contain the chief part or body of 

 the inhabiting animal, the nature of which is not yet properly understood, 

 appears, however, to be in some degree allied to the genus Sepia, but is desti- 

 tute of long arms or claspers, instead of which it is furnished with several 

 rows of short, broad, subdivided or palmated teutacula, spreading in a ra- 

 diated direction round the mouth or beak : it is also provided with a con- 

 cave expansile hood or process, which it is supposed occasionally to extend 

 by way of a sail. 



The animal is figured in Shaw's Nat. Misc. Plates 579 and 580. Its colour 

 is deep pink. 



With a very few exceptions the Nautili have only been found to inhabit 

 the ocean. 



Genus 20.— CON US. 



Animal a Limax ; shell univalve, convolute, turbinate ; 

 aperture effuse, longitudinal, linear, without teeth, entire at the 

 base ; pillar smooth. 



This genus in the Linnean System is divided into five families : *haviDg the 

 spire or turban nearly truncate or flat ; **pyriform, with the base rotun- 

 date, and sub-cylindrical, the cylinder one half longer than the spire ; •*** 

 elongate, \^'ith the base rotundate, cylinder twice the length of the spire ; 

 ****ventricose in the middle, and narrow at each end ; *****ventricose, and 

 emits a tinkling sound when thrown on its back upon a table. 



Conns striatus — The Striated Cone. Plate VIII. fig. 20. 

 Ovate, oblong, gibbous, clouded, and with strong transverse striae. 

 Four inches long. Inhabits Africa and India. 



Conus varius. Plate 11. fig. 12. Rubbed through to show 

 the internal structure of the shell. D Spire, f body, m m m pil- 

 lar or columella. 



The Cones inhabit the ocean, and are generally found on rocky shores. 



Many of the Cones are very beautiful. Some of them are the highest 

 priced of all shells, from their great rarity. One species, the Cedo Nulli 

 of Lyonet, is valued at one hundred guineas. Cones are covered with an 

 epidermis, and it is not till this is removed tiiat their beauty can be seen. 



