414 Natural Histo7-y of Molluscous Animals: — 



Among the other families of gasteropodes, I do not re- 

 member any that are exclusively carnivorous, except the 

 genus Testacellus, to outward appearance scarcely differing 

 from the common slug, but distinguished by carrying a small 

 shell above the tail, and a species of Vitrina, or shelled ter- 

 restrial snail, found under stones in moist, shady, or grassy 

 situations in the higher parts of the Island of Madeira. Un- 

 like the slugs, the Testacellus burrows in the soil, and is the 

 dread of the earthworm on which it feeds ; and these habits 

 are accompanied with corresponding changes in its organis- 

 ation. Its body is more cylindrical than that of the slug, and, 

 in lieu of a shield confined to a limited portion of the neck, 

 the whole body is encased with a thick coriaceous coat, to 

 guard from the additional pressure to which it is exposed, 

 and to afford sufficient strength to execute its furrows. But 

 the most marked differences are found in the digestive organs. 

 In the mouth there is no corneous denticulated jaw, nor a 

 membranous spinigerous tongue ; but from between two ver- 

 tical lips issues a very small cylindrical proboscis, and appro- 

 priated to it a muscle which forms the most curious part in 

 the structure of the creature. It is large, cylindrical, lies 

 along the whole belly, and is attached to the left side of the 

 back by a dozen of very distinct fleshy slips, almost perpen- 

 dicular to the principal muscle of the body. (Cuvier, lib. cit, 

 Mem, xii. 7.) The size and strength of this muscle indi- 

 cate its paramount importance ; nor do all its actions seem to 

 be ascertained, although one of its uses is certainly to retract 

 the proboscis, and probably at the same time to grasp with 

 firmness the struggling victims of its ferocity.* The carni- 



* Since this letter was written out for the press, a very interesting paper 

 on the Testacellus has been published in this Magazine. (VII. 224.) From 

 the observations of Mr. Denson, it is proved that the animal has the power 

 of suddenly darting out its tongue to seize its prey : — " It is projected and 

 applied in an instant ; and, when applied, the action of a muscular struc- 

 ture, connected with its origin, draws it, and with it the worm, into the 

 slug's mouth." (p. 227.) We now know the use of the remarkable muscle 

 of Cuvier. — G. J. 



I have, in p. 226 — 230., shown, that, after I had made the remarks there 

 published, 1 had found that equivalent and many additional ones had been 

 published, long before, by M. de Ferussac and Mr. G. B. Sowerby. The 

 following one, from Mr. G. B. Sowerby, I strove to present in p. 227., in 

 connection with those there published ; but want of space excluded it : — 



" We have observed them [individuals of T. scutulum] attentively, and 

 were rather surprised that an animal generally so extremely sluggish in its 

 motions, after discovering its prey by means of its tentacula, thrusting from 

 its large mouth its white, crenulated, revolute tongue, should instantly 

 seize upon, with extraordinary rapidity, and firmly retain, an earthworm of 

 much greater size and apparent force than itself; but which, by its utmost 

 exertion, is unable to escape." (G. B. Sowerby y in his Genera of Recent 



