NOTES ON RETICULARIAN UHIZOPODA. 265 



undesirable basis for the division of an unusually variable 

 group. The number of varietal forms that can be said to 

 have uniformly only three external segments is exceedingly 

 limited, whilst on the other hand, most of the QuinqueloculijicB 

 have a triloculine stage of growth. Under d'Orbigny's defi- 

 nitions young specimens and adults of the same variety have 

 over and over again been placed as new species in separate 

 genera. Amongst smooth-shelled forms the anomaly might 

 pass unnoticed, but amongst those in which peculiarity of 

 surface-ornamentation affords the principal distinctive cha- 

 racter the double nomenclature becomes a palpable absurdity. 

 There is still another objection to these generic terms, which 

 is brought into stronger light by specimens obtained from 

 the " Challenger" dredgings, namely, that the number of 

 exposed segments is not necessarily either three or five. In 

 one striking subarenaceous species, which I propose to name 

 Miliolina aXteolinifortnis, there are often seven or eight, long, 

 narrow chambers in the peripheral whorl. There is another 

 arenaceous form (Miliolina triquetra, nov.), in which, instead 

 of two segments, one up and one down, forming the axial cir- 

 cuit of the test throughout, there are in the final circuit three 

 segments, the contour becoming flattened in the same way 

 as in Biloculina co7itraria, and more or less triangular. 

 Neither of these could be included in any of the Milioline 

 genera as hitherto constituted. Instances of the same sort 

 might readily be multiplied, but enough has been said to show 

 that TrilocuUna and QuinquelocuUna ought now to be dis- 

 carded as generic or even subgeneric names, just as Adelosina 

 was long since abolished and for similar reasons, and that 

 some general name less open to objection should be found 

 for this portion of the group. 



The term Miliola naturally suggests itself, but that and 

 the corresponding 31iliolites were used by Lamarck for the 

 entire series, whether bi-, tri-, quinque- or spiro-loculine, and 

 in this sense it has also been applied by Messrs. Parker and 

 Jones and others to the Serpida seminulum of Linne, as the 

 central type of the whole group. Prof. W. C. Williamson, 

 after discussing the question with his usual shrewdness,^ 

 employs the modified term Miliolina for the section under 

 consideration. I can see no objection to this course, and am 

 inclined to think that with some modification of the charac- 

 ters assigned to the genus, in the monograph referred to, its 

 general adoption would be a distinct gain to zoologists. 



Concerning the other MiUolicla there is little that need be 

 said in these preliminary notes. Some points of interest in 

 * ' Recent Foramiuifera of Great Britaiu,' p. 83. 



