and Physiology of the Spongida. 39 



specimen, unless very large or very small and of definite form, 

 goes for nothing specifically. 



All the calcareous sponges are small, and many diminutive, 

 even when full-grown ; while many species of siliceous ones 

 have been found of very large dimensions. Thus, while the 

 cavity of Grantia ciliata may when full-grown only admit a 

 pin's head, a small child might sit down in the great suberitic 

 siliceous sponge called " Neptune's cup." Dr. Bowerbank, in 

 a note written to my friend the late Dr. J. E. Gray, mentions 

 a massive sponge (Suberite, mihi) nearly as large as a "military 

 drum j" and the crown of another from Belize, in the Bay 

 of Honduras, " 3 feet across." The well-known " Neptune's 

 cup," just mentioned, also belongs to the Suberitida. Mr. 

 Clifton, again, in a note to Dr. Gray (which I possess), states 

 that he has seen specimens of a branched sponge (Axos 

 Cliftoni. Gray) on the beach in South Australia, after a storm, 

 " 6 feet long." In the British Museum there are many species, 

 too, of totally different sponges, massive, excavated and fron- 

 dose, or flabelliform, of comparatively gigantic growth ; but, 

 as I have before stated, they are only indications of the size 

 that some sponges may attain, aud therefore of little or no 

 value specifically. Still the smallest and most amorphous 

 fragment of a sponge which presents a new set of spicules 

 should not be overlooked. That called "Acarnus innominatus, 

 Gray," I first found on a large specimen of Ectyon sparsus, 

 Gray, from the West Indies, in a fragmentary state not larger 

 than the human nail ('Annals,' 1871, vol. vii. p. 273, pi. xvii. 

 figs. 4-6), a specimen of which as large as the human head 

 was afterwards presented to the British Museum, from Ceylon, 

 by Mr. Holdsworth. 



Parasitism. 



As no living being is exempt from parasites, so the sponges 

 have theirs. Algse, polypes, cirripedes, and crustaceans live 

 in and on them respectively, as I hope to show hereafter in a 

 separate and illustrated communication. One parasite in 

 particular, for which I have proposed the name of Spongio- 

 pliaga communis ('Annals,' 1871, vol. viii. p. 330), so entirely 

 replaces and simulates the sarcode of the original sponge, in 

 Hircinia especially, that, but for its occurrence in many other 

 sponges of a totally different kind and in different parts of 

 the world, it might (as it has been) be considered part of the 

 sponge itself. 



