187G.] 



Biology of the ' Valorous' Cruise, 1875. 



227 



only two or three trircadiate Rhahdammina centra presented themselves ; 

 so that I feel justified in concluding that the long straight rods are not 

 rays of Rhahdammina broken off from their centra, but that each repre- 

 sents two elongated and straightened-out arms of a Rhahdammina whose 

 third arm is abortive. The gradation towards the orthocerine Lituola^, 

 marked by their occasional imperfect segmentation, is only another 

 case of that general doctrine of intimate mutual relationship "^ hich I 

 have on several occasions pointed out as existing in each of the two 

 groups of perforate and imjperforate Calcareous-shelled Foraminifera, 

 and which, when all the new deep-sea Arenaceous types shall have been 

 carefully worked out, will be found, I feel confident, to be completely 

 applicable to that third series which is now coming to rival the other two 

 in the variety of its forms. 



"What is the relation between the xlrenaceous and the Calcareous - 

 shelled Foraminifera (whether the former are the elder, and the latter the 

 derived forms), is a question on which I shall at present only suggest, 

 reserving what I have to say upon it to some future opportunity. 



Diato:ms. 

 By Professor Geoege Dickie, E.L.S. 



Mr. Gwyn Jeffreys, during the voyage of the ' Valorous,' collected by 

 means of the towing-net, in lat. 58° 55' N., long. 34° 18' W., a peculiar 

 organism having the appearance of a small sponge. It was found to 

 have a very wide range, extending over some thousands of square miles. 



The general aspect of a specimen preserved in spirit is such that it 

 might be readily mistaken for a sponge. 



Specimens were submitted to Dr. Bowerbank and Mr. Carter. They 

 both reported it not to have the character of a sponge. The latter was 

 more specific in his opinion, and pronounced it be a Diatom, probably a 

 Synedra. Before receiving Mr. Carter's report I had arrived at the same 

 conclusion. 



The organism is a new species of the genus Synedra, and remarkable 

 on account of the large proportion of colloid matter which seems to 

 connect the frustules in masses. The former may be compared to the 

 sarcode, the latter to the spicules of a sponge ; but there is mere re- 

 semblance only. It is further notable on account of the gi'eat length 

 of the frustules as contrasted with their breadth. 



The countless multitudes of this Diatom and of others of the same 

 family, and the extent of sea over which they extend, are points of much 

 interest, contributing directly as they do to the support of various smaller 

 marine animals, and these in turn to larger forms, adding also to deposits 

 taking place at various depths. I add a brief description of Synedra 

 Jeffrey si : — ^Trustules greatly elongated, straight, in front view linear, 

 ends subcapitate, no pseudo-nodule, in side view linear rectangular, 



R 2 



