NOTES ON RETICULARIAN RHIZOPODA. 295 



probably an exclusively pelagic type, and I have never met 

 with a dredged specimen the shell of which was more than 

 approximately complete. A comparison of Cymbalopora 

 hulloides Avith two or three species of the same genus not 

 having the large globular chamber Avould lead to the belief 

 that it also may be of essentially pelagic habit. 



But it is with the genera Glohigerma and its immediate 

 allies, and Puhinulina, that we are chiefly concerned in the 

 present inquiry. Of nine recent species, or well-marked 

 varieties of Globigerina (proper), at least two-thirds occur in 

 the surface gatherings ; indeed, though there are three or 

 four forms that hUve not been satisfactorily traced, the only 

 ones conspicuous by their absence are Gl. duhia, which 

 represents the most finely developed modification of the 

 '' hulloides " type, and Gl. digitata, the most divergent of 

 all from the normal form in its structural features. The 

 Orbuline Glohigerince are represented by 0. unicersa in 

 thin-shelled condition, and the absence of the very rare 

 0. neojurcnsis need not excite surprise. 



Amongst the Sph(Broidin<2, the thick-shelled Sph. dehiscens, 

 with its coarsely tubulated Avails, is not uncommon, whilst 

 the thin- shelled Sjjh. hidloides has never been met with at 

 the surface. One species of Pullenia (P. ohliqueloculatd) is 

 found sparingly at the surface, whilst the two smaller forms, 

 P. sph<Broide8 and P. quinqueloha, are only known from 

 dredged specimens. Lastly, Puhinulina supplies at least 

 five forms to the surface fauna, all of them pertaining to 

 one section of the genus : of these, two are rare, P. crassa 

 and P. 3Ienardii, var. tumida, and of them the number of 

 specimens found is insufficient for purposes of comparison or 

 argument; the rest are very common. Other PulcinuUnai, 

 found in abundance in dredgings from great depths, have 

 never been obtained by the towing-net. 



If the GlohigerincB obtained from the surface of the ocean 

 are compared with specimens of the same species collected 

 by the dredge, certain differences are at once apparent, the 

 most conspicuous of Avhich is the frequency of hirsute or 

 spinous shells in the former, and their comparative absence 

 from the latter source. This is so readily accounted for that 

 it need not be d^velt upon. It has already been stated that 

 nearly all the morphological varieties of Globigerina may be 

 found at times covered Avith these long silky spines ; and on 

 the other hand, though the spinous condition is very frequent 

 in pelagic shells, it is by no means invariable. 



Another point of some importance is the relatively smaller 

 size of the surface specimens. This has been made the 



