26o DISCOVERY REPORTS 



obvious affinities with C. cettcola, Nelson, in the characteristically curved raphe and in 

 the sculpture of the lower valve, but other notable differences appear to justify the foun- 

 dation of a new species. Chief among these are the much greater width of the girdle 

 (20-30/x) and the very much stronger curvature of the valves. In addition the valves are 

 longer in proportion to their breadth, and altogether larger than the largest known 

 valves of C. ceticola {ca. 30 x i8ju.). The size of the valves of C. wheeleri was of the order 

 of 35-42 X 20-22/x, and the girdle was produced into acute projections at the ends of 

 the lower valve. The impression that we are concerned with a species hitherto unknown 

 gathers strength from the fact that this form was observed upon Humpback whales 

 only. A microphotograph of this species is shown in Plate XI, fig. 5, and the points 

 mentioned above are also indicated in fig. 6 and 7. A formal description of this species 

 is as follows : 



Cocconeis wheeleri, n.sp. (Plate XI, figs. 5-7) 



Raphe, partibus mediis et striis valvae inferioris similibus C. ceticolae, Nelson, sed 

 lanceolatioribus, valvis valde arcuatioribus. Mensura valvarum 35-42/x x 20-22/x. 

 Altitudo cesti 20-30/x . Cesto producto in projectiones acutas in extremis valvae inferioris. 

 Hab. in cuti cetorum Megaptera nodosa, South Georgia. 



When first encountered during the 1930-1 season it was thought that it possibly 

 represented C. ceticola in a stage of auxospore formation, but the slightness of the 

 action exerted by solvents upon the girdle, and the large size of the frustules, soon 

 served to dispel this notion. 



Navicula sp. ? A minute species of Navicula characterized by the possession of well- 

 marked central and terminal nodules (Plate XI, fig. 9) was frequently found upon 

 whales. The striation of the valves, if present, was too slight to be made out under 

 ordinary conditions, and accordingly its specific identification has been deferred. In rare 

 instances this diatom occurred in such numbers as to form film in the absence of C. 

 ceticola. On one Blue and one Sperm whale it was observed to have penetrated the 

 epidermis, with the result that the latter showed marked signs of deterioration in 

 patches, the main feature of this apparently pathological condition being the develop- 

 ment of a brownish colour. Sections across such patches showed the diatoms densely 

 packed along the dermal layer with their long axes at right angles to the surface of the 

 whale's body (Plate XI, fig. 8). Perhaps in correlation with this apparently parasitic 

 habit the endochrome of these diatoms was observed to be of a very pale greenish, 

 almost colourless shade, similar to that of the diatoms found in the baleen. 



Navicula spp. Several small species of this genus were met with in the skin film 

 from time to time in numbers such that they were almost certainly present when the 

 whales were alive, but since they formed but an insignificant proportion of the film as 

 a whole, and their identification presents special difficulties, no attempt has been made 

 to name them. It is noteworthy that the colour of the endochrome of these diatoms 

 was comparable to that of the C. ceticola among which they were found. 



Gyrosigma (Rhoicosigma) arcticum, Cleve (Plate XI, fig. 10). Individuals agreeing 



