FROM THE EDDYSTONE C! ROUNDS TO START POINT. 443 



grains lyiug as nearly as possible side by side without overlap. The 

 figures were as follows : — 



102 VI f., 13 c. grms. by weight, 48 forarainifera. 



103 VII. 



90 VII. 



91 VII. 

 87 VII. 

 97 VII. 



105 VII. 



106 VII. 

 83 VII. 



)) 



I) 





203 

 104 



67 



81 



60 



29 



29 



93 „ R H. W.] 



PORIFERA. 



The only two species of sponges of which satisfactory records were 

 kept are Snterites domuncula and Cliona celata. The sponge fauna was 

 nowhere numerous on the grounds ; but in addition to the above, two 

 or three other unidentified species were occasionally taken. 



Stiberites domuncula was met with, forming the dwelling of the 

 hermit crab Uupagurus cuancnsis. 



Cliona celata. The importance of this species is very great, for, 

 boring as it does in mollusc shells of all kinds, it is the chief agent 

 which brings about their disintegration, and prevents their continued 

 accumulation on the sea-floor. On all the coarse grounds in the 

 neighbourhood of the Eddystone there are few shells, with the excep- 

 tion of those which are obviously quite recently dead, which have 

 not been attacked to a greater or less extent by Oliona, and a large 

 number are reduced to what is little more than a framework held 

 together by the sponge. 



Hydrozoa. 



[^Nomenclature : — Hincks, British Hydroid Zooiihytcs^ 



In this group I have received much assistance from my friend 

 Mr. E. T. Browne, the specimens in a number of hauls having been 

 identified by him. For geographical distribution I have relied largely 

 on Hartlaub (No. 38). 



The iiijluence of the hottom-dejoosit on the distribution of hydroids. 

 The Hydrozoa being all fixed organisms, the nature of the bottom- 

 deposit has in most cases, either directly or indirectly, a very great 

 influence on their distribution, and in an area such as that examined 

 during the present investigation, where the remaining physical con- 

 ditions to which the grounds are subjected are practically the same 

 for all, this influence can be very largely traced. 



Considered from the point of view of their modes of attachment. 



