322 



Gasteuopoda." 



-MOLLUSC A. Proboscidifeka. 



of the family, is of a creani-wliite colour, very hand- 

 somely marked with rows of brown spots. The Spotted 

 Anger is from six to eight inches long, and of an 

 elegant shape. It is a native of the southern seas and 

 the Indian ocean. 



Family III.— PLEUEOTOMID^ {Slit-mouths). 



The family of Slit-mouths or Pleurotomas 

 {Pleurotoniida), have somewhat nearer relations with 

 the Cones than the Auger-shells. The teeth are simple, 

 elongate and rather enlarged at the base, and the outer 

 lip of the shell has a notch or slit at or near its upper 

 e.xtremity. The siphon is produced, and the mantle 

 has a slit in the hinder part of the outer side, corre- 

 sponding with the notch or slit in the lip of the shell. 

 The foot is oval, short, thin on its edges, and carries on 

 its posterior extremity a pretty thick, horny, annular 



operculum, wliich varies considerably, and forms a good 

 character for separating the species into groups or sub- 

 genera. The shell is fusiform, with a turriculated spire, 

 more or less elongate, with roundish whirls, and the 

 aperture, which is ovate, terminates in a more or less 

 elongate, straight canal. The Pleurotomae are carni- 

 vorous in their habits, and the family contains many 

 species, which are world-wide, extending from Green- 

 land to Australia, and from low water to one hundred 

 fathoms. None of the species are of great size, the 

 largest scarcely exceeding four or five inches in length. 

 THE TOWER OF BABEL (Pleiirotoma Bahylonica), 

 a native of the Indian seas and the Moluccas, is the 

 typical species of the genus. It is from three to four 

 inches in length, turriculated, with convex whirls ; is 

 of a white colour, with circular keels or ridges which 

 are spotted transversely with black square dots. The 

 canal is rather long. 



Sub-order II.— PROBOSCIDIFEKA. 



This sub-order contains a much larger number of 

 species than the preceding, and many exceedingly 

 interesting and valuable shells are found amongst them. 

 The animals are carnivorous, feeding upon living mol- 

 hisca and other animals, and they are often found boring 

 round holes in shells to arrive at their inhabitants. 

 " Many wage war on their own relatives, and take 

 Ihem by assault; the bivalve may close, and the oper- 

 culated nerite retire into his home, but the enemy with 

 rasp-like tongue, armed with silicious teeth, files a hole 

 through the shell — vain sliield where instinct guides 

 the attack ! Of the myriads of small shells which the 

 sea heaps up in every sheltered ' ness,' a large pro- 

 portion will be found thus bored by the whilks or 

 purples ; and in fossil shell-beds, such as that in the 

 Tcuraine, nearly half the bivalves and sea-snails are 

 perforated, the relics of Antediluvian banquets." — 

 ( Woodivard.) At page 1 84, we have described tlie teeth 

 of the gasteropodous mollusoa, and have mentioned 

 there, that they are silicious in their composition ; and 

 being placed in the Proboscidifcra or carnivorous species 

 in several rows on a lingual ribbon, which is muscular 

 in its structure, we can easily conceive wliat powerful 

 weapons they prove in penetrating the hardest shells 

 or coverings of their prey. As animals which live on 

 animal food require the blood to be more perfectly 

 aerated than those which feed upon vegetables, so in 

 the Proboscidifcra we find that they are provided with 

 a siphon attached to the inner side of the front part of the 

 mantle, which enables the water more freely to arrive 

 at their breathing organs ; and the shells are always 

 formed with a canal placed in front of the pillar in 

 01 der to protect this siphon from iiijury. The proboscis 

 is long, and being furnished with a number of muscles, 

 can be exscrted a great way from the head, and with- 

 diawn again like the horns of a snail, so as to be hidden 

 within the bodj' — see fig. 52, proboscis of Buccinum. 

 The tentacles are placed close together at the base of 

 the proboscis, or are united by a veil at that part.; and 



the ej'es are sessile, generally on the outer side near 

 the base of these tentacles, though sometimes they are 

 placed at the tip or behind them. The animals are 

 unisexual, and the females are generally much larger, 

 and have much more ventricose whirls to their shells, 

 than the males. The eggs are contained in a kind 

 of horny or leathery (coriaceous) cases, each holding 

 man}' eggs, but only a few of which ever come to 

 perfection. " The cases of Buccinum undatum (our 

 common whilk) and Fusus dcspectua have been mis- 

 taken for the eggs of the oyster, and called Oystcrspat. 

 This error is the more remarkable as oysters are ovovi- 

 viparous, the young being found in the branchioe of the 

 parent in the month of July ; the eggs of Purpura and 

 other genera have, by a similar error, been described 

 as a species of Tuhidaria." — {Gray.) The lingual 

 ribbon of these animals is placed near the apex of 

 the exsertod proboscis, and the teeth are arranged in 

 one, three, or seven rows ; the gills are placed in two 

 series along with some mucous filaments. The oper- 

 culum, when present, is horny and annular. The 

 shells of the different species are subject to great 

 variation, according to the roughness or smoothness 

 of the sea they live in, and the quantity or quality of 

 their food. Some of the common wdiilks {Buccinum 

 undattini), for instance, are thick and rugose, others are 

 very thin, even, and finely coloured. These have been 

 described as distinct species. Examples may be seen 

 in the fine collection of shells in the British Museum. 



We will now, taking that magnificent collection as 

 our guide, proceed to mention some of the more 

 important families of this sub-order. 



Family I.— CASSIDULIDiE {Fig-shells). 



The family of Fig-shells (genus Pijrula of Lamarck ; 

 family Cassidulidce of Gray) are the first in order. As 

 constituted by the celebrated Lamarck, the genus 

 Pi/rula contains several types dissimilar amongst them- 



