BULIMINIDAE 127 



sections are too thick. Of their existence there can be no doubt, at least in D. sutilis 

 and D. wiesneri; probably also in the other species. 



(vi) The protoplasmic body is very voluminous. In specimens taken out of spirit and 

 dried for sectioning it occupies and almost fills every chamber. It is very clear and free 

 from inclusions of any kind and pink in colour. 



From the foregoing observations it is evident that in Delosina any interchange of 

 protoplasm between the diflFerent chambers, and between the interior and exterior of the 

 shell, can only be effected via the tubuli, which are minute. It follows that all food must 

 be digested and assimilated outside the test by the extruded protoplasm. This would 

 account for the absence of stercomes in the internal protoplasm. The functions of the 

 canals are entirely mysterious, but they may perhaps act as a circulatory system for 

 water. They can hardly have any advantage over the tubuli as exits for the protoplasm, 

 as the canals though of greater diameter than each tubule are few, while the tubules are 

 infinite in number. 



I am still almost as uncertain as hitherto with regard to the proper systematic position 

 oi Delosina. The single instance in which a Bulimine aperture has been seen is the only 

 fresh evidence of possible afiinities, and on that account I am transferring Delosina to 

 the Buliminidae, but without any definite conviction that the genus will remain there. 

 Neither Cushman nor Galloway in their recent systematic publications have found a 

 resting place for Delosina. It has no very apparent connection with any other genus; 

 though externally resembling both Bulimina and Polymorphina, its points of difference 

 exceed those of resemblance. The sieve-like apertural face suggests Pegidia and Spliaeridia 

 in the Pegididae, but there the resemblance ends. The canal system appears to be unique. 

 Finally, there is a peculiar quality in the material of which the test is constructed which 

 appears to be distinctive. Although hyaline and perforate the shell substance has none 

 of that glassy clearness which might be expected in a thin-walled form, but appears to 

 have a granular basis. There is a certain opalescent density in even the smallest and 

 thinnest specimens which marks them as different from other hyaline Foraminifera. 

 I should not be surprised if future research removed the genus to a new family esta- 

 blished for its reception. 



Sidebottom figured several diflFerent organisms under the name Polymorphina ? 

 complexa, and described none of them. For purposes of future reference I have, by com- 

 parison of the original types and published drawings, separated the records into five 

 species. 



262. Delosina complexa (Sidebottom) (Plate V, fig. 16). 



Polymorphina complexa, Sidebottom, 1904, etc., RFD, 1907, p. 16, pi. iv, figs. 1-3, and 



text-fig. 6. 



? Polymorphina complexa, Heron-Allen and Earland, 1914, etc., FKA, 1915, p. 673, pi. li, fig. i. 



Two stations: 175, 181. 



Test hyaline, thin-walled, finely perforate, round or oval in section, tapering to each 

 extremity, the aboral end more or less acutely pointed. Chambers few in number, long 

 and embracing, three to a convolution, the final convolution occupying the greater part 



