228 



Characteristics and Habits of Testacdlus 



keep the orifice clear of soil, while the animal progresses 

 through this pulverulent material. [I have since seen that 

 M. de Ferussac has expressed, and more positively, both 

 these ideas ; and Mr. G. 13. Sowerby, also, that on the remark- 

 able power of extension and attenuation of body given to the 

 Testacelli. Fig.4<\. h shows their great power of contraction.] 



Mr. Blair's remarks, in VI. 43., intimate that the Testa- 

 cellus does not hibernate ; Mr. Lukis's facts, above, teach 

 the same thing; and a couple of facts known to me point to 

 the same conclusion. The Testacelli (of the species T. scutu- 

 lum, at least) seem to be, with regard to hybernation, in 

 precisely the condition of the naked slugs, whose case has 

 been so accurately described by G. J. in p. 116, 117. The 

 fact told of a T. scutulum, in VI. 44., from Mr. J. Sowerby, 

 jun.* ; and that related above by Mr. Lukis, of a Testacellus 

 laying its eggs after being twenty minutes in a warm room, 

 suggest that the Testacelli are, indeed, especially sensitive of 

 variations in temperature. 



Since the above remarks were w^ritten, we have striven to 

 meet Mr. Lukis's wish for a statement of the diagnostics of 

 the species of Testacellus. Mr. J. D. C. Sowerby has, in 

 relation to this object, supplied the following figures (j^.^l.) ; 



J S h i 



and we have transcribed, with his permission, from his copy 

 of Baron de Ferussac's Histoire Naturelle Generate et Parti- 

 culiere des Mollusques Terrestres Fluviatiles, the diagnostics 

 there given of T. haliotideus, Mauge?, and ambiguus; and 

 from Mr. G. B. Sowerby's Genera of Recent and Fossil Shells, 

 the one there given for T. scutulum, which is a species that 

 was unknown to Ferussac at the time that he published those 

 here quoted from him. 



T. haliotideus Faure Biguet. Animal : Flavidum, rufum, vel griseum, ma- 

 CLilatum aut immaculatum ; tentaculis cylindricis. Testa : Ovata postice 

 acuminata, cornea, crassa, extus rugosa, intus nitida; clavicuia [inner 

 lip G. B. Sowerby] alba lata et plana. 



♦ Since removed from among us by death. This most amiable and most 

 promising young man died of a tubercular consumption, on February 7. 

 1834, aged 18 years. His loss to us all, and to science, is feelingly regretted 

 by every one whom his uncommon modesty allowed to know him. 



