BRITISH SPONGIADJE. 175 



length by six in breadth, and the same in height, but it is 

 evidently a portion only of the original mass. Mrs. Brett, 

 to whom I am indebted for my knowledge of this species, 

 obtained it between the tide marks on the northern side of 

 St. Katherine's Rock, at Tenby, and the colour, I am in- 

 formed, was the same when alive as when dried, light gray, 

 approaching closely to white. 



The variation in the size, and the modifications in the 

 form of the spicula of the skeleton is remarkable. The 

 normal form is evidently acuate, elongate, and not flexu- 

 ous ; the short and stout varieties of the normal form are 

 often flecto-attenuato-acuate, and the longer and more 

 attenuated varieties of the normal form are usually more 

 or less flexuous. Acerate or cylindrical spicula are of rare 

 occurrence, and are often inflated near the middle of the 

 spiculum. 



The skeleton spicula vary from -th to ^th of an inch in 

 length. The same tendency to great variation in size 

 here prevails among the bihamate spicula, but of these 

 there appears to be two distinct groups, one ranging 

 in length from ^th to ^th of an inch, and the other 

 from j^gth to ~ 5 th. inch. The latter are infinitely more 

 numerous than the former ones, but both are inter- 

 mixed on the surface of the membranes without the slightest 

 appearance of arrangement, while the minute acerate spi- 

 cula of the same tissues are usually collected in fasciculi, 

 irregularly disposed on the surface of the membranes. 

 These spicula do not exceed ^th part of an inch in length, 

 and are exceedingly slender. The slender flexuous acuate 

 spicula abound on the surface of the interstitial membranes, 

 and they are also intermingled with those of the skeleton. 

 The flecto-acuate spicula are considerable in number, and 

 somewhat uniform in size, but I could not ascertain that 

 they were peculiar to any one portion of the sponge. The 

 inflato-acuate are rather rare, the inflation is tolerably uni- 

 form in size but not in position, sometimes being in the 

 middle of the shaft, and at others near its base. 



In the dried condition, the texture of this sponge is 

 very open and cavernous. 



