BemarJcs on the Foraminifera. By Prof. T. Rupert Jones. 85 



longitudinal ribbing of Nod. raphanus, we have the thick costata 

 (F. and M.), and the weaker ariminensis, D'O. In C. ornata, 

 D'O., this ornament is dying out. 



An excessive crest, accompanied with thinness (compression) of 

 the chambers, gives rise to the large and elegant Crist, cassis and 

 its subvarieties. 



When the keel is subdivided into spines, like the rowels of a 

 spur, cultrata becomes calcar (Lin.) ; and margaritacea, rosacea, 

 rostrata, and marginata are among the names given to subvarieties. 

 Granules on umbones and septa, or all over, are frequent in the 

 subvarieties of C. calcar and C. cassis. 



Some of the above-mentioned features and conditions are evi- 

 dently gradational ; the others are related by many similar grada- 

 tions not here mentioned, but some of which are indicated in the 

 Table. 



The long, flat Cristellariae, retaining something of the Marginu- 

 line growth, but with the posterior or downward angle of the 

 chambers reaching almost or quite down to the excentric umbihcus, 

 are known as Planularim, very delicate and pretty shells. PI. 

 crepidula (F. and M.) is little more than a Marginulina and rather 

 less than a Cristellaria of the rotidata group, but thin and im- 

 perfectly coiled ; its modifications are endless ; when keeled, it is 

 elongaia, D'O. ; rostrata, D'O., when mucronate also. With bolder 

 convexity and better development of the apertural margin, with 

 more numerous and neater chambers, and some trace of costate 

 ornament, we have PI. auris* Defrance, and its smaller forms 

 cymha and auricida, D'O. 



Conclusion. — Without having exhausted the subject, I think 

 that these remarks may be usefully suggestive to beginners and 

 students. One good piece of work that promises satisfactory results 

 would be the careful copying and collating of all the figured forms 

 of each "genus" and "species" of Foraminifera, so that their 

 gradations and their distinctions might be seen at a glance, and the 

 right appellation, according to priority and worth, be awarded to 

 the types and subtypes. These appear to have come from very 

 early times, increasing their varieties under every new set of modi- 

 fying conditions to which they were introduced. These varieties 

 have sufficient fixedness to give a peculiar /a a'es to the several local 

 groups of Foraminifera, fossil or recent ; and, insomuch, their chief 

 forms require a nomenclature for reference and identification. 



The remarkable persistence of Foraminiferal types, in general 

 character, has been often noticed ; and their conservative tendencies, 

 due to their simplicity and universal adaptability, has been com- 



* Batsch figured this shell, together with Frondicularia and Flahelluia, calling 

 them all Nautilus harpa, an appropriate name, had he defined the separate form. 



