Remarks on the Foraminifera. By Prof. T. Rupert Jones. 71 



groups, a similar form of shell, but with considerable differences of 

 structure. 



The '• agathistegian " growth of shell, so characteristic of Miliola, 

 is represented in the Perforata by Allomoiyhina and Chilostomella, 

 and among the sandy forms by Trochammina milioloides. On the 

 other hand, the nautiloid, or disco-spiral, segmented growth, so 

 characteristic of the Perforata, is found in Lituola (L. nautiloidea 

 and L. canariensis), Endothyra, and Trochammina (T. inflata) 

 of the sandy group ; but it is only approached in the Im2)ei'forata 

 by Hauerina and Dendr/tina. The OrhicuUnida (porcellanous) 

 correspond, in annular and subdivided chambers, with Eetero- 

 stegina, CyeJoclypeus, &c. (hyaline). 



The alternate arrangement of chambers, seen so frequently in 

 the Hyalina, is less common ( Valvulina) in the Arenacea (unless 

 we include the sandy Textularise and Buliminm), and does not 

 appear among the Porcellana. 



Thus we see some general features of resemblance between all 

 the three great groups, in the style of growth and arrangement 

 of the segments, as represented by the shell ; and occasionally still 

 more binding links, such as the passage from the Perforate through 

 Valvidina and its arenaceous allies to the Imperforate group. We 

 also see very close kinship between some of the so-called " families," 

 and decidedly among the members (so-called " genera ") of these 

 subgroups, though we have here looked at only those of the Por- 

 cellana and Arenacea, and that very cursorily. It is well known 

 that the distinctive naming of the members of the so-called 

 " genera " of Foraminifera almost amounts in some cases to naming 

 the individuals themselves ; and that " subgenera," " species," 

 " subspecies," and " varieties " are terms easily applied to specimens 

 differing less and less from a chosen type, the characters of which 

 exist for us only in the shape, ornament, and other features of a 

 simple shell. Doubtless the real zoological distinctions (whatever 

 their relative value may be) are to be found in the morphology 

 of these Microzoa : doubtless also their shells have the impress of 

 their original and successional conditions, but these characters are 

 obscured to a very great extent, and wait for further elucidation. 



The following extract from a memoir by my friend Prof. 

 W. K. Parker and myself, in the ' Quart. Journ. Geol. Soc.,' 

 vol. xvi., 1860, pp. 293, 294, expresses the views on this subject 

 we then entertained, and which we still hold, looking, however, on 

 " species " of Foraminifera as more comprehensive, and less easily 

 defined, the more exact our acquaintance with them becomes. 



" With respect to the nomenclature adopted in our Tahle (of fossil and recent 

 Foraminifera of the Mediterranean and Euxine areas, loc. cit., p. 302), we have, in the 

 first place, been careful to eliminate all unnecessary binomial terms, such as dupli- 

 cate names, or names given to but slightly varied individuals; and at the same time 

 we have enumerated many well-marked varieties in each species, because of their 



