328 



GASTEROrODA.- 



-MOLLUSCA.- 



-Pboboscid:feka. 



shell, and almost entirely conceals it fiom view. Being 

 Bmoolh aiid provided with a slimy mucous secretion, 

 it thus covers (he surface of the shell with a fine layer 

 of bright enamel. Some species possess an operculum, 

 but others have none. 



Genus Harpa. — The Harp shells are well known 

 to collectors, and are fiivourite objects of their research; 

 the richness of their colours, and the elegance of their 

 forms causing them to be much sought after. They 

 are swollen ventricose shells, with an ample mouth 

 and a short spire. They are all distinguishable at first 

 sight by a number of elegant longitudinal ribs, and a 

 highly-polished callosity on the front part of the colu- 

 mella. At present nine species have been described, 

 but at the time of Linn£eus only one was known, which 

 he described as a species of Buccinum {B. harpd). The 

 animal which inhabits the shell was not known even 

 to Lamarck, when he founded the genus Harpa. M. 

 Raynaud, however, a surgeon in the French navy, was 

 enabled to give some details of a species found by him 

 alive in India, and his observations were afterwards 

 confirmed by MM. Quoy and Gaimard. It resembles 

 that of the Olive shells, having a very large foot, which 

 is divided into two portions. The anterior half is 

 broad, but the posterior portion is elongate, terminates 

 in a sharp point, and is nearly as long as the whole 

 shell. It is so disproportionately large indeed, that it 

 cannot be quickly withdrawn within the shell. The 

 animal, therefore, has the power, when suddenly at- 

 tacked by an enemy, of spontaneously detaching this 

 hinder portion, by pressing it firmly against the lip of 

 the shell, or by means of a sudden contraction, and 

 thus enabling it to withdraw the rest of its body within 

 the shell. It possesses the faculty also of reproducing 

 the lost portion after a time. There is no opercu- 

 lum, as such an appendage would be of no use to the 

 animal, since it would be separated by ths rupture of 

 the foot. 



THE SWOLLEN HARP [Harpa ventricosa) " glories 

 in a rich vermilion red skin." At the Jlauritius it is 

 caught, like the Olives, with lines baited with small 

 pieces of flesh. " It is the amusement of the place," 



Fig. 215. 



The Many-ribbed Harp (Harpa imperialis). 



says Mr. Broderip, " to watch over the trim apparatus 

 of lines hung over some sandliank to tempt the various 

 brilliant species of Oliva which there abound, or to 

 Wait for the more rare approach of the Harp shell, till 



the rich hues of its inhabitant are seen glowing through 

 the clear blue water, in the rays of a tropical rising 

 sun." 



THE MANY-RIBBED HARP (Harpa imperialis) is 

 one of the rarest and most beautiful, and perhaps the 

 most precious of all the species. Though now much 

 depressed in value, it was at one time a shell of high 

 price — fig. 215. 



Placed here by Dr. Gray, comes a small family of 

 molluscs, very unlike any of the preceding, as far as 

 the shell is concerned, but brought amongst the Probos- 

 cidifera, by the structure of the teeth and the form of 

 the animal. 



Family— LAMELLARIID^. 



This family have a thin, pellucid, spiral, ear-shaped 

 shell, with a large patulous aperture, and a receding 

 inner lip. The mantle is large, and completely covers 

 the shell ; the proboscis is elongate, strong, and retrac- 

 tile ; and the tongue is linear, and spirally twisted 

 behind, as in Purpura. The family is represented in 

 Plate 1, figs. 1-4, by the species Ermea perspikua, 

 which is a native of Great Britain, and fig. 5, Coriocella 

 nigra. 



Family— FASCIOLARIID^. 



This family contains the Tulip shells and the Mitres. 



Genus Fasciolaria. — The Tulip shells are fusi- 

 form, elongated, and swollen, with a conical spire. The 

 whirls are round and smooth, or angular and waved ; 

 the mouth is ovate, outer lip crenated, grooved within ; 

 columella tortuous with several oblique folds in front. 

 The canal of the shell is elongate, and the operculum 

 claw-shaped, with the nucleus apical, sometimes radiately 

 grooved. The species are not numerous, only about 

 sixteen having been described ; but the}' have a wide 

 range in their distribution, being found in the Medi- 

 terranean, Cape Verd islands. West Indies, Ceylon, 

 Philippine islands, Australia, Western Africa, and South 

 America. One of the species, the Gigantic Tulip shell 

 {Fasciolaria gigantea), from the South Seas, is very 

 large, sometimes attaining a length of nearly two feet. 



Genus Mitra. — The Mitres have a fusiform shell 

 with a conical, elevated spire, compressed whirls, a 

 small mouth, and a short canal. The columella is 

 obliquely plaited with about five folds, and the oper- 

 culum, when present (it is wanting in the larger species), 

 is very small. The mantle of the animal is inclosed, 

 and the foot is small, folded longitudinally when con- 

 tracted. The proboscis is generally very long and 

 large, that of Mitra episcopalis being more than one 

 and a half times the length of the whole shell, and being 

 capable of being projected to the distance of five inches. 

 The species are numerous, exceeding three hundred 

 and fifty, and vary very much in form and sculpture. 

 They are found chiefly harbouring in the Philippine 

 Archipelago and other groups of islands, few occurring 

 on the shores of continents, and in deep water from fifteen 

 to eighty fathoms. When irritated, some of them emit 

 a purple fluid having a nauseous odour. The larger 

 species are said to be sluggish animals. This seema 



