G. GENERAL NATURAL HISTORY AND ZOOLOGY. 343 



very much like the so-called Bathyhms. The letter will be 

 found in JSI'ature, August 19, 1875. 



PROFESSOR T. RUPERT JONES ON THE FORAMINIFERA. 



Professor T. Rupert Jones has published a paper on the 

 variability of form in the foraminifera, especially as illus- 

 trated in the Cristellarians. The systematic grouping at 

 present in greatest favor is based primarily on the texture 

 of the shell, ^:>or(3e^^a?20M5, hyaline^ or sandy ; and, secondarily, 

 on the arranojements of the segments of sarcode and the form 

 of the shell chambers; and the author considers this the most 

 natural method of grouping these extremely variable forms. 

 While it is undoubtedly true, as Professor Williamson sug- 

 gested as long ago as 1818, " that the hard shells of the fo- 

 raminifera do not constitute a sufficiently constant and im- 

 portant element in their organization to justify our trusting 

 to them as guides in the discrimination of species" (here re- 

 ferring to form rather than texture), we doubt very much 

 whether the grouping based on texture can be any better 

 relied upon. In the paper to which wx have alluded. Pro- 

 fessor Jones, who is, indeed, the highest authority, shows the 

 gradual passage of these groups into each other; and he states 

 that there are evidently several points where the diiferentia- 

 tion of the great foraminiferal groups is by no means abso- 

 lute, and that there are some general features of resemblance 

 between all the three great groups in the style of growth 

 and arrangement of the segments, and occasionally still more 

 binding links. Certainly any system of classification that 

 will do away with the unlimited multiplication of quasi-spe- 

 cific names, linked together by pseudo-generic titles, which 

 can only weary the catalogue-maker and throw obstacles in 

 the way of the systematist, should be accepted with thank- 

 fulness ; but there is yet very much improvement to be made 

 upon the system proposed by Messrs. Jones, Parker, and 

 Brady, and we doubt, after all, whether form, with all proper 

 allowance for possible variations from a normal type, is not 

 at present as safe a basis for classification as shell structure. 

 Thus the two otherwise undistinguishable gQner^x^Cornuspira 

 and Trochaimnina (as represented by T. incerta)^ are sepa- 

 rated by the latter method, yet we are quite certain, from 

 specimens obtained from soundings in the Bay of Campeche 



