168 BEITISH SPONGIAD^. 



resemble both in size and form tbose of i2. intermedmm, 

 but B. simpUcissimum is entirely" destitute o£ bihamate, 

 retentive spiculaj and in the dermis the spicula are 

 very numerous and are irregularly dispersed, and in 

 no degree approaching reticulation. The loosely 

 fasciculated dermal spicula and numerous rosette- 

 shaped groups of retentive, inequi-anchorate spicula in 

 the dermis of B. sordidum readily separate it from 

 B. intermedium. In truth the sponge in course of 

 description is really an intermediate species between 

 B. svmplidssimwm and B. sorAidMm. 



" It is quite possible, though not very probable, from 

 the rarity of the inequi-anchorate spicula in B. inter- 

 medivm that hereafter a few rosette-shaped groups may 

 be found in well-developed specimens of the species ; 

 as we find in B. sordidum they do not occur equally in 

 all parts of the dermal membrane, and in some por- 

 tions of it they are entirely absent.'* 



Genus 24, — Spongilla, Linn., i, 199 ; ii, 10. 



1. Spongilla pluviatilis (Pallas), ii, 339 ; i,- PI. IX, 

 figs. 217, 218; PI. XXH, figs. 517—519; iii, 

 PI. LIX. 



1867 Ephydatia flwoiaiilis, Gray. Proc. Zool. Soc, p. S50. ] 



2. Spongilla Pabpitti, Garter, in, 298, PI. LXXXVI, 

 figs. 5—12. 



1868 Spongilla Mayeni, var. Parfitti, PariB.tt. Sponges of 

 Devonshire, Trans. Devon. Assoc. Liter. Sci. and Art, 

 p. 17 (separate copy). 



