Remarks on the Foraminifera. By Prof. T. Rupert Jones. 75 



As Lagena, so Nodosaria occurs in a compressed form, and is 

 then known as Lingulina ; and this bent and partially coiled is 

 Lingulinopsis. A Lingula much outspread on each side, by the 

 overreaching of the chambers, in stretching backwards, becomes a 

 Frondicularia ; and if this has an excentric or coiled beginning 

 it is a Fldbellina, which, without the backward lateral stretch of 

 its later chambers, would be a simple flat Cristellaria (Planiilarla). 

 If a Frondicidm'ia ceases to have outspread chambers, and grows on 

 as a Nodosaria, it is Amjpliimorpliina. 



A flattened Dentalina, with oblique chambers, is Vagmulina ; 

 and if the aperture be a rift along the front of the chamber, instead 

 of a round hole at the margin, it is Rimulina ; and a Vaginidina 

 with coiled commencement is either nearly or quite a Margiyiulina, 

 which without its straighter portion is a Cristellaria. 



Trigonal or quadrilateral Nodosari^e, known as Orthoeerinae, 

 usually have a thick shell ; but some take on a Nodosarian or Denta- 

 liue growth in advanced age, and are then termed Dentalinopsis. 

 Their relationship is indicated by this style of growth ; CristellaricB, 

 Marginulinfe, and Vaginulinee have the same habit. 



Infinite gradations of form connect the "' genera " and " sub- 

 genera " enumerated above ; and the same habit of ornamentation 

 obtains throughout, namely, ridges and riblets, often broken up 

 into prickles, or dying away in granules. In the subdiscoidal 

 and the nautiloid forms a marginal, and often a single dorsal, 

 crest is the reduced, or concentrated, rejDresentative of the ridge 

 ornament. The thickening of the septal edges, and of the um- 

 bones, is frequent and extremely variable. Lastly, the relative 

 size and proportion of the segments (and consequently their shape 

 in coiled shells) produce some of the greatest differences in the 

 aspect of Nodosarine and especially Cristellarian shells. This 

 variability in the size of the chambers in closely allied individuals 

 seems to rest on the peculiar habits of the animal, — its well- or 

 iJl-fed condition, its freedom of growth, and such like ; and, if the 

 chambered segments are specially connected with the reproductive 

 processes,* other reasons for relative difierence of size may exist ; 

 but the gradational conditions are such as to preclude any idea of 

 the proportional size of chamber being a specific character. 



Cristellaridea. — The many " trivial " names and binomial 

 appellations given to Cristellarians (as indeed to all other con- 

 generic Foraminifera) have been sore troubles to the cataloguist, 

 though of some little use to the collector, and even to the pakeon- 

 tologist, in recognizing the individual kinds of Microzoa, which 

 difier so much in external appearance. In reducing them, however, 

 to zoological order, to which mere external aspect is not the chief 



* As Mr. Carter suggests fm' Opcrculini, ' Annuls Xat. Hist.,' scr. 4, vol. xiv 

 1875, p. 423. 



VOL. XV. U 



