BRITISH SPONGES 



2. HALICHONDRIA, Fleming. 



Halichondria, Flem. Brit. Anim. 520 — Halina, Grant in Edin. 

 Encyclop. xviii- 844. — Haliclona, Grant, Outl. Comp. Anat. 5. 

 — Halispongia, Blainv. Actinolog. 532. 



Character, Body multiform, more or less spongious and 

 elastic, often friable lohen dried, permeated hy canals open- 

 ing by oscida on the surface, composed of fibro-corneous and 

 siliceous threads woven into an irregular net-work, or of si- 

 liceous spicula variously crossed and netted together by a ge- 

 latinous cement ; surface porous, usually more compact in 

 texture than the interior, and not slimy : spicula simple, 

 crystalline. Marine. 



The name of the genus, says Dr Fleming, is derived from 

 ya^ic, silex, and %wh^bc, cartilago ; and there seems to be no 

 good reason for adopting the alterations of it which Dr Grant and 

 De Blainville have proposed. It is, upon the whole, an arti- 

 ficial group, embracing species which would never have been 

 brought under one head, had their form or apparent structure 

 guided us in the collocation of them ; and, accordingly, we find 

 the species scattered by authors through the genera Spongia, 

 Alcyonium, and Tethea, or collected under other and new generic 

 names. Even in regard of their composition, the Halichondriae 

 exhibit very considerable diversity, but they pass into one ano- 



