126 DISCOVERY REPORTS 



sutures, A.E.) do not open directly into the chambers, but generally into a canal running 

 under the suture". Of the species he writes: "According to Sidebottom the apertures 

 are sieve-like on the apertural surface. He does not mention the rows of pores on the 

 sutures. Our specimens on the other hand have merely single pores on the apertural 

 face, and also at other points on the chambers, which at the sutures form into rows". 

 Wiesner's great contribution therefore is the information that a canal underlies the 

 suture, and that the rows of pores which Sidebottom and Heron-Allen and Earland had 

 figured opened into this canal, the existence of which had not previously been suspected. 



Through the kind offices of Herr Wiesner, Professor A. Schellenberg of the Zoo- 

 logical Museum, Berlin University, has allowed me to examine the stock of specimens 

 of Delosina collected at the Winter Station of the ' Gauss'. The majority of the speci- 

 mens are of Wiesner's "broad" form {D. wiesneri, No. 266) which is the commoner 

 species in the Kaiser Wilhelm's Land area, and they attain a larger size and greater variety 

 of construction than would be imagined from the few specimens obtained from the 

 Discovery material. There was also a single specimen of the "slender" form (Z). sutilis, 

 No. 265) which appears to be very rare, and another specimen oi D. complexa (No. 262), 

 sensii stricto. The chief value of the material to me was that Wiesner's canal system and 

 its branches, the " stitches ", could be distinctly seen in fragments of dead shells. I had 

 been unable to see it in the Discovery material, except for the brief interval during which 

 the canal becomes visible as an air-filled tube when specimens are immersed in fluid. 

 It vanishes as soon as the fluid has expelled the air, and it is hardly visible in my sections, 

 possibly because they are not thin enough. 



The three forms found by the ' Gauss ' are all present in the Discovery material but 

 in diff'erent proportions, the "slender" form D. sutilis occurring with some frequency, 

 the others being very rare. Before Wiesner's work came into my hands I had already 

 succeeded in grinding sections of D. sutilis, the greater size and thickness of the shell 

 enabling me to succeed where Sidebottom had failed with the smaller Mediterranean 

 specimens. The sections did not add a great deal to the sum of knowledge, but the fol- 

 lowing points were made out : 



(i) The great majority of the specimens are megalospheric, the megalosphere being 

 very large and pear-shaped. 



(ii) In one section the megalosphere has a loop-shaped aperture at its inner or narrow 

 end, communicating with the second chamber. It is strongly suggestive of a Bulimine 

 aperture. 



(iii) Otherwise, there is no direct communication between the successive chambers, 

 other than through the fine tubules in the walls. 



(iv) There is no general aperture on the final chamber. The coarse perforations of 

 the sieve figured on the apertural face of the final chamber by Sidebottom, and by 

 Heron-Allen and Earland, do not penetrate through the shell wall. They appear to be 

 short branching canals in the thickness of the wall, which is evidently spongy in this 

 area, and to be the termination of the Wiesner canal underlying the suture. 



(v) The Wiesner canals are not clearly visible in the sections, probably because the 



