264 A MONOGRAPH OF THE 



24. Halichondria Hyndmani, Bowerbank. 



Sponge. Branching and anastoDQOsing from numerous 

 small attenuated bases ; branches slightly compressed, 

 terminations corymbose. Surface rugose, hispid. 

 Oscula and pores inconspicuous. Dermal membrane 

 thin, transparent, furnished with a few, dispersed 

 bidentate inequi-anchorate retentive spicula. Skele- 

 ton. Spicula attenuato-acuate, semi-spined basally, 

 somewhat stout. Internal defensive spicula attenuato- 

 acuate, entirely spined, few in number. Interstitial 

 membranes. Tension spicula cylindrical, slender and 

 flexuous ; retentive spicula bidentate inequi-anchorate, 

 minute, dispersed ; and simple and contort bipocil- 

 lated anchorate spicula, minute, dispersed. Sarcode 

 abundant, dense and purple in the dried state. 



Colour. — Alive, light yellow. Rev. WalterGregor; purple, 

 J. S. Bowerbank. In spirit, dark purple ; when dry, brown, 

 with a tinge of purple. 



Habitat. — Strangford Lough, Messrs. G. C. Hyndman 

 and Wm. Thompson. Moray Frith, Rev. W. Gregor. 

 Hastings, J. S. Bowerbank. 



Examined. — From spirit, alive, and dry. 



This highly interesting little sponge was dredged in 

 Strangford Lough, in June, 1846, by Messrs. Hyndman 

 and Thompson, in from fifteen to twenty fathoms water ; 

 it is based on the shells of Pecten opercularis. The largest 

 specimen is one and three quarters inches in length by one 

 and a quarter inches wide, and one inch in height. It was 

 attached to the shell by a number of small basal points,- 

 but the whole by anastomosis forming one sponge. In 

 several other smaller specimens the same peculiarities of 

 character exist. The termination of each branch of the 

 sponge is corymbose, and the terminations of the whole, as 



