198 A MONOGRAPH OF THE 



to the same authority, " on the rocks, at the lowest spring 

 tides only." 



28. Hymeniacidon jecusculum, Bowerbank. 



Sponge. Coating ; surface corrugated, slightly hispid. Os- 

 cula simple, dispersed: submarginated, slightly ciliated. 

 Pores inconspicuous. Dermal membrane pellucid, 

 abundantly spiculous ; spicula acerate, long, and 

 slender ; inner surface furnished with numerous stout 

 angulated, equi-anchorate, retentive spicula. Skeleton : 

 spicula attenuato-acuate, basally spined, long and 

 stout, occasionally subclavate ; spines rather short and 

 small. Internal defensive spicula attenuato-acuate, 

 entirely spined ; short, occasionally subclavate ; spines 

 large and long. External defensive spicula acerate, 

 like those of the dermal membrane. Spicula of inter- 

 stitial membranes acerate, long, and slender, sometimes 

 flexuous, numerous. Retentive spicula, angulated, 

 bidentate, equi-anchorate, rarely tridentate, large, and 

 stout, exceedingly numerous, 



Colour. Alive, vermilion-red; dried, dark flesh-red. 

 Habitat. Caves, Island of Harris, Hebrides ; Capt. F. 

 W. L. Thomas, R.N. 



Examined. In the dried state. 



I am indebted to my friend Captain Thomas, of the 

 Hydrographical Survey, for this new and interesting-species, 

 which he found on the side of a cave on the coast of the 

 Island of Harris, at low water spring tide. In its present 

 dried condition it is one inch and a half in length, three 

 fourths of an inch in breadth, and four lines in thickness, 

 and in colour and appearance very closely resembles a thin 

 slice of sun-dried muscle of beef or mutton; but when 

 alive, my friend states it is of a pure vermilion-red colour. 

 The surface is irregularly corrugated, and the corrugation 

 appears to be produced principally by the slightly elevated 



