LITHOTRYA. 



TESTA irregulariter subpyramidalis, lateribus 

 compressis^ pedunculo tubuloso^, tendineoque im- 

 posita, octovalvis; valvis contiguis, inaequalibus, 

 lateralibus sex^ inferioribus minimis ; dorsali 

 magna^ ligulata^ anticd minutissima. Appendix 

 testacea patellam inversam referens^ ad basim 

 pedunculi. Animal intermedium inter sessiles et 

 pedunculatos Cirripedes, saxorum cavos, ab ipso 

 terebratos^ incolens. 



We are happy to have an opportunity of introducing to 

 our readers a new Genus, partaking of the peculiarities of 

 both Lamarck's orders of Cirripedes, being pedunculated 

 like Anatifa^ &c. but having at the base of the peduncle a 

 shelly appendage, analogous to the testaceous base of 

 Acasta and Balanus, and possessing besides, a peculiarity 

 not to be found in any hitherto described Genus of this 

 class, that of penetrating stones for its habitation. This 

 Genus is an instance among others in proof of the necessity 

 of an acquaintance with the animals inhabiting and pro- 

 ducing shells, and of the importance of an intimate 

 knowledge not only of their forms and external characters, 

 but also of their habits and economy; inasmuch as a 

 knowledge of the shelly portions of it alone, would convey 

 to us but a very imperfect idea of the subject ; it would 

 present to us a few irregular and dissimilar valves which 

 we should not know how to place so as to describe their 

 relative situations ; we have even known instances in 

 whichr various detached parts of some of the shells of some 

 Cirripedes have been mistaken for bivalves, as the base of 

 Acasta might very easily be for a Patella. Linne united 

 into a single Genus all the shells which compose Lamarck's 

 class Cirripedes, because, although there is so great a 

 diversity among the shells themselves, he has well observed 



