ALCIPPE LAMPAS. 553 



Hancock noticed this edging of hard shelly matter, and 

 naturally thought it was a secretion. Lines of deposi- 

 tion (PL 22, fig. 4, b), parallel to the edges of the furrow 

 can often be perceived in it : its thickness and extension 

 vary much : I have seen it on one side alone of the ori- 

 fice : it is, of course, never found at the broad end where 

 the process of enlargement goes on. The peculiar worn 

 surface with which it irregularly thins away downwards, on 

 the sides of the cavity, made me (together with the apparent 

 impossibility of such a secretion proceeding from an animal 

 wholly invested by a chitine membrane) suspect it to be 

 inorganic; and this view is certainly correct, for when a 

 fragment is dissolved in acid, a considerable residium is left 

 of bits of membrane, rubbish, and, in one instance, even of 

 the remnants of a foreign animal, apparently an annelid. 

 We have here all the circumstances favorable for inorganic 

 deposits of this nature, namely, finely triturated shell and 

 chitine or animal matter, produced by the excavation of the 

 chamber, sea- water, and movement. 



From the manner of growth of the animal, the fissure 

 leading into the cavity in the shell becomes much longer 

 than the orifice leading into the sack, and to prevent the 

 body being unnecessarily exposed, the upward projection of 

 the disc, already described, is formed under the narrow and 

 disused end of the fissure ; moreover, the two rims of the 

 inorganic calcareous deposit sometimes here approach so 

 closely, as almost or actually to touch each other; and 

 between them, as remarked by Mr. Hancock, there is 

 usually a little accumulation of grains of sand. This 

 narrow end of the fissure is generally curled either to the 

 right or left hand ; and I can only account for this fact by 

 supposing that, whilst the cirripede is young, and has not a 



of cloth, offers another example of the strong tendency which lime and animal 

 matter have to unite. Lately, Dr. Horsford, in ' Silliman's North American 

 Journal,' Jan. 1853, has discussed the chemical theory in an analogous case on 

 the coast of Florida; he attributes the aggregation to the formation of a 

 hydrate of lime through the action of the animal matter. Mr. G. B. Sowerby, 

 Junr., has described a case very analogous to that of Alcippe, (' Proceedings of 

 Zoolog. Soc, Mollusca,' PL 5, tig. 4, p. 162, 1S50), namely, that oiPholas calca, 

 in which a tube is formed of inorganic calcareous matter, serving to narrow the 

 entrance. 



