3s8 DISCOVERY REPORTS 



Forty stations : 48, 51, 228, 230, 236, 388 ; WS 71, 73, 76, 77, 78, 80, 83, 84, 86, 87, 88, 89, 90, 91, 

 92, 93, 95, 97, 98, 99, 108, 109, 210, 213, 217, 219, 221, 225, 245, 246, 248, 408, 409, 433. 



Universally distributed and, at certain stations, forming a considerable proportion of 

 the whole bulk of the material. The species is evidently polymorphic, as two, or perhaps 

 three, very distinct forms occur at most of the stations in company. The first is a large 

 form which is the true d'Orbignyan Type as verified in Paris, although it is much less 

 delicate than his figure suggests, the markings being as a rule rather obscure (Plate IX, 

 figs. 26-28, 32, 33). It agrees in size with the d'Orbignyan dimensions, " Diam. i mm." 

 The test is thick- walled, opaquely white, the sutural lines nearly flush, sometimes quite 

 invisible, the peripheral edge generally showing no lobulation. Sections reveal both 

 megalo- and microspheric forms, there being little observable external difference, save 

 as regards size, the microspheric form being larger than the megalospheric, and 

 generally flatter. 



The second form is quite small as compared with the foregoing, rarely attaining one- 

 fifth of its dimensions (Plate IX, figs. 29-31). It is thin-walled, very hyaline and the 

 chambering is clearly visible as in d'Orbigny's figure, the peripheral edge being slightly 

 lobulate, as he describes it to be. We have not been able to cut sections of this form, but 

 owing to certain differences in size and external characteristics which we have observed 

 in a series of specimens, we have every reason to believe that both micro- and megalo- 

 spheric specimens occur in this small form as well. This smaller form is the type which 

 has been usually met with by us in gatherings practically all over the world. The large 

 type on the other hand we have only met with in high latitudes both north and south, 

 so it is presumably confined to colder waters. 



A third form, which may be described as intermediate, is in size from three to four 

 times the diameter of the small form, and partakes of the external characters of the large 

 form, of which it is probably an immature or pauperate stage, though it is occasionally 

 found at stations where the large form is not recorded, viz. 51 and WS 86, 89, 98, 213, 

 217, 225. At stations 228, 230, 236, and WS 95, 221, 408, 409, only the small form was 

 found, and few and poor specimens at that. As these stations are widely separated, we 

 can offer nothing in explanation. 



161. Cassidulina crassa var. porrecta, var.nov. (Plate IX, figs. 34-37). 



Eleven stations: 388; WS 76, 83, 84, 88, 89, 91, 93, 97, 210, 225. 



At many of the stations where the large type of C. crassa occurs, there is a tendency to 

 a form of variation characterized by the drawing out of the final chamber into a more or 

 less produced terminal portion. The variation is unquestionably a form of senile 

 deterioration, as it affects only the last few chambers of large and mature specimens. No 

 young individuals with drawn-out final chambers were observed. Seen by itself the 

 variety would be sufficiently striking to warrant a separate specific name, but there is no 

 doubt that it is merely a local and senile variation. The best and most characteristic 

 specimens occur at stations WS 83 and 91 and especially at 388. At first sight the variety 

 recalls Cassidulina braziliensis , Cushman (C. 1918, etc., FAO, 1922, p. 130, pi. xxv, 



