Cornuspira diffusa. By E. Herun-AIlen and A. Earland. 275 



ance. Its size diminishes to a maximum of 3 mm., and, while 

 retaining the characteristic shape and striolation of the test, the 

 shell assumes a delicacy and fragility comparable with C. diffusa, 

 which possesses the same striolate surface in a less marked degree. 

 It is not difficult to account for the development of the tubular 

 and ramifying scheme of growth. The object of the wide slit- 

 shaped aperture evolved by C.foliacea Philippi sp., and in a more 

 advanced stage by its ally C. striolata Brady, is obviously to secure 

 immediate access for the pseudopodial outgrowths to extended 

 feeding grounds in the superficial ooze. In some specimens of 

 C. striolata. the slit -like aperture extends over more than half of 

 the entire periphery of the shell. This increase of aperture must, 



Fig. 36. 



however, have its detrimental feature in the increased fragility of 

 the test, there being no internal septa to strengthen and support 

 the two thin parallel walls. It is, therefore, not surprising to find 

 that some of the large deep-water specimens of C. striolata show a 

 tendency to variation in the direction of tubular outgrowths, which, 

 while strengthening the general aperture of the shell, allow ready 

 passage of the pseudopodia to the ooze. From this stage to the 

 development of the ramifying protean growths of G. diffusa, the 

 transition appears to be slight. 



In the plates to the ' Challenger ' monograph {supra) Brady 

 figures a " monstrous specimen " of Cornuspira foliacea Philippi 



