Mr. H. J. Carter on the Gumminese. 25 



If we were to see a tough, wet, shining lump of dough lying 

 on a piece of sponge in our bath-room, there would be no hesi- 

 tation in distinguishing the two objects ; but if we were to 

 observe something like this attached to a sponge growing on a 

 rock in its natural habitat, the probability is that it would be 

 a Gummina. Such may give some idea of the typical form 

 of the Gumminese. 



As yet only one species has been noticed on the British 

 coasts ; and that has been designated by Johnston " Halisarca 

 Dujardinii" after the illustrious naturalist who first described 

 and gave it the name of " Halisarca " (a\to9, marine, and 

 <rapf*, flesh). Johnston found it in Berwick Bay, and has 

 given the following description of it in his ' British Sponges,' 

 published in 1842 (p. 192), together with a figure (pl.xvi. f. 8) : — 



" Halisarca, Dujardin. 



" CHARACTER. Substance fleshy or rather gelatinous, semi- 

 transparent, unorganized, forming an irregular crust on the 

 objects to ivliich it adheres. 



" 1. H. Dujardinii (plate xvi. fig. 8). 

 " Halisarca, Dujardin, in Ann. des Sc. Nat. n. s. x. p. 7, pi. 1. fig. 5. 



u Hab. On the underside of stones between tide-marks, and 

 on the stalk and roots of Laminaria digitata, common. Ber- 

 wick Bay; Holy Island (G. J.). 



" Sponge in the form of a gelatinous crust, spreading irregu- 

 larly, about a line in thickness ; the surface even and smooth, 

 of a straw or ochre-yellow colour, mottled with little pale cir- 

 cular spots or pores, produced apparently by a deficiency of 

 colouring-matter in their places. A few of these transparent 

 spots are larger than the others ; and if the former have any 

 relation to the pores of the true sponges, the latter may be the 

 analogues of the fsecal orifices. 



" This production is liable to be mistaken for one of the 

 crustaceous Compound Tunicata, or, rather, for the gelatinous 

 spawn of the naked mollusca; but a careful inspection easily de- 

 tects the difference. This exhibits no trace of any oviform bodies 

 or cellular tissue, and contains neither crystals nor spicula, but 

 is no other thing than a mass of irregular and granulous 

 globules, of great minuteness, that lie imbedded in a clear jelly, 

 covered over with a more consistent and coloured skin. Dujar- 

 din has ascertained that, when broken up, the separated masses 

 shoot out from their sides delicate prolongations or filaments 

 of various lengths, and slowly change their figure, in the same 

 manner as do the detached sarcoid pieces of the freshwater 

 sponges (see woodcut no. 9, p. 61)." 



