530 



MOLLUSCA. 



and tliiis, as tin- fislKTiiK'H sav, it perishes by suffocation. Oppian, fifteen hundred years ago, 

 charircd the star-tish with sinular atrocities : 



"The prickly star creeps on with fell deceit, 

 To force the oyster from his close retreat. 

 When gai)iiit!; lids their widen'd void display 

 The watchful star thrusts in a pointed ray ; 

 Of all its treasures si)oils the rifled case, 

 And empty shells the sandy hillocks grace." 



Nor have wo oven yet iiioiitioiiod all the cahuuities of the oyster; the insidious Drill — Fusus 

 ciueri'HS — punctures their shells by thousands, nay, by millions, and thus extracts the juices on 

 which life depends. Many parts of the sea are paved with shells, bearing evidence of these sub- 

 marine enormities. We need not pause to consider how like all this is to what we witness in 

 every human town or city, where we constantly behold the shells of men who have been uncon- 

 sciously tlrilled and sucked dry by the various kinds of sharp, sly, insidious Fusi Cincrei wliich 

 live and breathe and have a fat, prosperous, and respectable being, among men. 



Class VI. TlJIlflCATA. 



These animals present the appearance of shapeless gelatinous masses ; they are composed of 

 two tunics : the outer one is the mantle, and the inner one lines a large respiratory cavity. 

 They are divided into two orders, the Biphora and Ascidice. 



ORDER 1. BIPHORA. 



Tliis includes a group of free, swimming animals, usually of a glassy transparency, the bodies 

 of which may be compared to a tube furnished with two openings, one for the entrance and the 

 other for the exit of the water. Those of the genus Salpa possess an elastic external membi'ane, 

 so transparent that the whole interior structure may be seen through it ; by the contractions and 

 expansions of this jets of water are created, which cause the animal to move along. The Salpse 

 are divided into Aggregate and Solitary^ but these are only different states of the same species. 

 They are minute animals, sometimes seen floating on the sea in long chains. 



ORDER 2. ASCIDIiE. 



Forbes, in his "British MoUusca," says: "Rarely is the dredge drawn up from any sea-bed at 

 all prolific in submarine creatures, without containing few or many irregularly-shaped, leathery * 

 bodies, fixed to sea-weed, rock, or shell, by one extremity or by one side, free at the other, and 



presenting two more or less prominent orifices, from which, 

 on the slightest pressure, the sea-water is ejected with great 

 force. On the sea-shore, when the tide is out, we find similar 

 bodies attached to the under surface of rough stones. They 

 are variously, often splendidly colored, but otherwise are 

 unattractive, or even repulsive in aspect. These creatures 

 are Ascidice, properly so called. Numbers of them are often 

 found clustering among tangles, like branches of some strange 

 semi-transparent fruit. They are very apathetic and inactive, 

 living upon microscopic creatures drawn in with currents of 

 water, by means of their ciliated respiratory organs. The 

 leathery case is often incrusted with stones and shells, deco- 

 rated with parasitical, though ornamental plumes of coral- 

 lines, and not seldom perforated by bivalves, which lodge 

 themselves snugly in the tough but smooth skin." 



MASS OP COMPOUND ASCIDIANS MAGNIFIED. 



