50 ANIMAL PARASITES AND MESSMATES. 



also develop themselves on the eggs of the Plagiostoma, 

 and are then capable of living separately. In the sub- 

 stance of this polyp lives a crustacean, the nature 

 of which Mons. Lacaze-Duthiers has not yet made 

 known. 



The superb sponge, Eiqjlectella asijergilliim, the 

 elegant structure of which cannot be sufficiently ad- 

 mired, is, unlike the Alcyonium of the Dromia, rooted to 

 the soil, but nevertheless gives shelter to three kinds of 

 crustaceans : Pinnotheres, Palemonidae, and Isopods. 

 These supposed plants have been known for many years 

 under the Spanish name of Regadera, or the English 

 "Venus' Flower-basket;" they were first brought from 

 Japan, and afterwards from the Moluccas, and more 

 recently from the Philippine Islands . In almost all the 

 individuals which Professor Semper was able to study in 

 those parts, were found the same crustaceans. These 

 Euplectellde have just been met with to the south-west of 

 Cape St. Vincent, by Wyville Thomson, who has brought 

 up some from a depth of 1090 fathoms, while on board 

 the Challenger, This skilful professor has discovered 

 another sponge to the north-west of Scotland, at a 

 depth of 460 fathoms; it bears the name of Holtenia 

 Carpenteri; and I have in my possession a fine specimen 

 which I owe to his generosity, and keep as a souvenir of 

 the delightful hospitality which he extended to me at 

 the Edinburgh meeting. 



There are also sponges which construct a dwelling 

 in the abode of their neighbour. We find, among others, 

 a small sponge known under the name of Clione, which 

 establishes itself in the substance of the shell of oysters, 

 and hollows out galleries as the teredo does in wood. 



