232 A MONOGRAPH OF THE 



work is in error in considering the sponge described by 

 Dr. Grant in the 'Edinburgh Phil. Journ./ XIV, p. 114, as 

 the same species as Ellis's sponge. Dr. Grant has kindly 

 furnished me with specimens of the sponge that formed the 

 subject of his paper, and in neither external nor internal 

 characters does it agree with Ellis's species. I am therefore 

 induced to believe that my friend Dr. Johnston could not 

 have seen Dr. Grant's specimens when he wrote his ' His- 

 tory of the British Sponges.' Ellis's sponge has certainly a 

 prior claim to the name of panicea, and the species so ably 

 described by Dr. Grant must retain the name of Halicho/i- 

 dria incrustans, under which designation it is described by 

 Dr. Johnston, ' History of British Sponges/ page 122. 



This species is quite as variable in colour as it is in form. 

 When littoral it is most frequently yellow, orange or green; 

 but when from five or ten fathoms in depth, it is usually ash 

 gray or cream coloured. 



I cannot do better than to refer my readers to Dr. 

 Johnston's excellent history of this species in his work on 

 ' British Sponges/ for the general account of this very 

 protean sponge. The large number of species into which 

 its different forms have been divided by various authors 

 strongly illustrates the inutility of external form as a prin- 

 cipal specific character in the description of the species of 

 the Spongiadae. 



2. Halichondria glabra, Bowerbank. 



Sponge. Coating thin. Surface smooth and glabrous. 

 Oscula simple, very small, in dispersed groups of 

 three to five or six in number. Pores inconspicuous. 

 Dermal membrane translucent, furnished with an 

 irregular network of spicula, rete frequently multi- 

 spiculous ; spicula same form and size as those of the 

 skeleton. .Skeleton. Spicula sub-fusiformi-acerate, 

 long and slender. 



Colour. When dried, pale yellow 



