CASSIS. 



Genus Cassis, Lamarck. 

 Testa ovata vel triijono-ovata, ad iasiu canali remno ascen- 

 denie Urminata, spird brevi, anfractibus interdum vari- 

 qpsis, anfractu ultimo valde maxima, inflato ; colu- 

 mella sapissime plicato-rugatd vel granosd et plerwriqiie 

 late expunsd, aperturd elongatd plus minusve ani/usfd, 

 labro incrassato, dentato. 

 Shell ovate or triaugulaa-ly ovate, tenninating at the base 

 with a recm-ved ascending canal, spire short, whorls 

 sometimes varicose, last whorl very large, inflated; 

 columeDa most frequently pUcately wrinkled or 

 grained, and generally widely expanded, aperture 

 elongated, more or less narrow, lip thickened, toothed. 

 The Cassides, or Helmets, are a strong, muscidai", but 

 inactive group of moUusks, whose shell is mainly distin- 

 guished by its solid or inflated growth and short spire, 

 and by an abruptly ascendmg recurved canal, thi-ough 

 whicli the siphon conveying the water to the breathing 

 organs passes, and is of more than ordinary dimensions. 

 The head is stout and fleshy, prolonged into the tentacles 

 after the manner of Purpura and Buccinum., the eyes 

 being situated on the outer smface, near the base ; M. 

 Deshayes has, however, observed that in the C. sulcosa of 

 the Mediterranean they are elevated on a short pedicle. 



The calcifying functions of the Cassides are somewhat 

 vigorously exercised, some of the shells being of large 

 size and often of extremely soUd growth; the mantle 

 which lines the interior of the shell, extends in ample 

 folds about the aperture, and is fi-eely occupied in the 

 secretion of that rich display of enamel which, thi'ough 

 being deposited in layers of different tints, affords so 

 beautifid a material for the engraving of Cameos. The C. 

 MadagascarieuMS, on account of its finely expanded hp and 

 purity of colour, is particularly adapted for this singular 

 art of gem-engraving, practised by the ancients ; and the 

 well-known ' Bull's Mouth,' C. rufa, is also much used. 

 The opercidum of Cassis is very pecuhar; it is of a 

 honiy composition, of an elongated crescent form, crenu- 

 lated along the edge, and rayed with deep stria;. 



We have no representative of this genus on our own 

 coast, and only one species, C. sulcosa, ranges so far north 

 as the Mediterranean. According to the observations of 

 M. Deshayes, it lives upon the juices of difl'erent Bivalves, 

 whose shells it penetrates with its proboscis, like the 

 Murices. 



The chief localities noticed in the following monograph 

 are China, the Molucca and Philippine Islands, AJgoa 

 Bay and the islands of the Pacific, the West Indies, New 

 Holland, and New Zealand. It should be observed, liow- 

 ever, that the species are but sparingly distributed, and 

 very few new ones have been collected during the last 

 few years, amongst the vast numbers that have been 

 discovered of other genera. The shells present a lively 

 display of coloiu-s, and, from their singular plan of growth, 

 constitute a very characteristic type in the great series of 

 Gastropods. 



Species 1. (Fig. a, h, c, Mus. Cuming.) 

 Cassis torquata. Cass, testa ovatd, spird suhacumbiutd, 

 anfractibus evaricosis, convexis, lavibus, columelld basi 

 imiplicatd, labro quinque- vel sex-spinoso ; fnlwscente- 

 lacted, anfractibus maculis quadratis intense castaneis 

 equidistantibus miperne et inferne uniseriativi picfi.i, 

 labro castaneo macidato. 

 The enchained Helmet. Shell ovate, spire somewhat 

 acuminated, whorls destitute of varices, convex, 

 smooth, columella one-plaited at the base, Hp fivc- 

 or six-spinose ; fulvous cream-colour, whorls painted 

 round the upper and lower parts with a row of equi- 

 distant, square, dark chesnut spots, lip spotted with 

 chesnut. 



Variety (3. (Fig. I.e.) 

 Testa iucrassata, anfractibus superne nodoso-tuhei-culatis. 

 Shell thickened, with the whorls nodosely tubercled round 



the upper part. 

 Hah. New Holland. 



This species, of which four excellent figm'cs were pub- 

 lished in 1773 by Martini (Couch. Cab. vol. ii. pi. 38. 

 f. 383 to 386), has been confounded hitherto with that 

 commonly known to collectors under its two-fold aspect 

 of C. viiex and erinaceus. It is uniformly of smaller size 

 and eminently distinguished by its style of painting, the 

 pattern of which does not consist of longitudinal flames 

 or dot-lines, but of two conspicuous chains of square 

 chesnut spots, one eneircUng the whorls immediately 

 beneath the sutures, the other at the base; the large 

 intermediate surface being clear and unspotted, beyond 

 three faint indications of bands. 



Ausust, 1S4S. 



