BRITISH SPONGIADiE. 163 



The tallest specimen did not exceed two and a half inches 

 in length, and was about a line in diameter, until near 

 the distal end, when it expanded to about a line and a half. 

 This specimen was from Torquay. The stoutest specimen 

 was from the Guliot Caves in Sark ; 'it was two inches long, 

 was largest about the middle, and the greatest diameter 

 was three lines. 



The base consists of a small irregular sessile mass, from 

 the top of which a single virgultose branch springs, gene- 

 rally very much more attenuated at the lower end than at 

 its middle or near its apex, where it frequently expands to 

 one and a half or twice its previous diameter ; sometimes 

 but not very frequently assuming a pear-shaped distal 

 extremity, but more frequently gradually attenuating from 

 the expanded portion to its apex. Occasionally, the branch 

 divides into two, but this is not of very frequent occur- 

 rence. 



In yomig, and apparently immature specimens, the basal 

 mass is often not present, the sponge consisting of a single 

 iraegularly cylindrical virgultose branch, and in this con- 

 dition it frequently attains two inches in height. 



The structure of this species is very simple, no other 

 form of spicula existing in it than those of the skeleton, 

 but they are very abundant and variable in size. I could 

 not detect the oscula in the living specimens, but in the 

 dried condition they were very apparent, but few in num- 

 ber. In the latter condition, the pores also were visible 

 when viewed by direct light with a power of 100 linear. 



The specimens were abundant for about six feet from 

 low water mark at spring tides, in the sides of the north 

 end of the furthest of the two large caves from the approach 

 by land, and which can be only reached by land at low 

 spring tides. 



8Hymeniacidon lactea, Bowerbanki 



Sponge, Coating, surface smooth and even. Oscula 

 simple, dispersed, minute. Pores inconspicuous. 



