LITHOTRYA. 



animal, and which may be compared to the operculum of 

 the Balani, are grooved at their bases, and covered with 

 minute impressed dots ; the inferior lateral valves very 

 small, approximated to the dorsal one, which is the largest 

 of all, and of the same width at its extremity as at its base, 

 generally transversely sulcated and dentated at its edges, 

 the anterior valve placed at the lower part of the aperture 

 and very minute. It has an irregular, shelly, cup-shaped 

 or inverted patelliform appendage, to the inside of which 

 the base of the peduncle is attached, and by which it is 

 fixed to the bottom of a deep regular cavity, undoubtedly 

 the work of the animal in a limestone rock. We cannot 

 undertake to explain the manner in which this animal 

 pierces the tubes in which it takes up its abode, but, inas- 

 much as all the specimens we have seen, amounting perhaps 

 to more than twenty, are all attached by the same means to 

 the innermost extremity of the same shaped holes, the 

 larger specimens having proportionably large holes; we 

 are compelled to believe that the animal possesses the 

 means of perforating calcareous stones, and we do not 

 think them bored, because they are rather elliptical, besides 

 which, we have formerly met with an animal of the same 

 nature, (probably of the same Genus) having also a shelly 

 base, inhabiting similar perforations in Oyster shells 

 brought from the Red Sea by the Earl of Mountnorris : 

 unhappily we have not the opportunity of comparing 

 these, having given our specimens to Dr. Leach some 

 years ago. 



In plate 166, f. 5, of the Encyclopedie Methodique, is 

 a representation probably intended for one of these animals, 

 but its shelly base is not distinguished ; and although it 

 shows the grooves in the dorsal valve, it is not in other 

 respects very good*. 



Of course we have never yet seen any fossil remains 

 of this Genus ; indeed among fossil remains those of the 

 edunculate Cirripedes are remarkably scarce, they occur, 

 owever, in the Crag of England, and the calcareous sand 

 of the neighbourhood of Paris. 



The specimens we have figured are from Montserrat, 

 one of the Antilles ; Mr. Charles Dubois has obligingly 

 favoured us with them. 



♦ Upon further examination, we find this figure is copied from Solander 

 and Ellis, pi. 15, f. 5, where we are told that it is a Lepas from the Mosquito 

 Shore, and a good Latin specific character is subjoinedj we have adopted 

 the specific nanae dorsaUs from that work. 



