546 Transactions of the Society. 



a fictitious, though to some extent a practical, value in these pseudo- 

 specific names, when the student is collecting and arranging Foraminifera, 

 if he is desirous of distinguishing minute differences by nomenclatorial 

 terms ; but he should not be led to exaggerate the zoological value of 

 such varietal forms and conditions. Further, were naturalists to use 

 only such terms as might be approved of by exact biology, the 

 discoveries and observations made by earlier authors would perhaps be 

 too often forgotten or laid aside. Indeed, it is necessary to retain for 

 classificatory purposes many names given by these earlier workers, and 

 very desirable that observers should refer to these older works thoroughly, 

 when seeking for comparisons and new names. Amongst the several 

 Bibliographies of Foraminifera known to us, that appended to H. B. 

 Brady's 'Keport on the Foraminifera of the Challenger Expedition' 

 is by far the best ; it has carefully brought the literature of the subject 

 into notice, and is very useful for the above-mentioned purpose of enabling 

 the student to find what has already been done in this line of research. 



Since 1860, the period at which our present Table closes, there have 

 been published a very great number of papers on the Foraminifera ; the 

 labours of Keuss, Terquem, Karrer, and others having brought to our 

 notice hundreds of forms, amongst which the Nodosarinse predominate. 

 Of these papers we do not propose now to treat j but it will be useful 

 to refer to a work, by von Schlicht,* who, in a series of thirty- 

 eight large plates, illustrating the Foraminiferal fauna of one deposit 

 (corresponding, according to Hermann Credner,t to our Hempstead 

 13eds of the Jsle of Wight), devotes eight and a half quarto plates, 

 containing two hundred and thirteen figures, to the Cristellarise alone. 

 To the delineation of other members of the Nodosarinae (Lagena to 

 MarginuUna) he gives ten and a half plates, with two hundred and 

 sixteen figures. Von Schlicht only grouped his specimens in " genera " ; 

 but von Keuss, in the SB. K. Akad. Wiss. Wien, Ixii. 1870, carefully 

 described most of the forms, making many new " species." The most 

 cursory examination of these plates will show the extremely close 

 connection existing between all the forms ; and, having in hand the 

 illustrations of so fine a series from one deposit, and therefore of so large 

 a group of forms most probably living continuously in one area, and 

 under one set of conditions, we are enabled to see in a striking manner 

 how greatly one form can and does pass into manifold varieties, and how 

 difficult it is to recognise the limitation of species, and say where they 

 begin and where they end.J 



It only remains to again point out the completeness of the chain 

 which has for its links the sub-groups Lagena, Glandulina, Nodosaria, 

 Dentalina, MarginuUna, Vaginulina, and Cristellaria (including 

 EoluUna) ; and again to draw attention to the infinite number of 

 varieties, whose only claim to " specific " position consists in the varying 

 curvature of the shell ; other modifications, such as surface-marking, 

 form and position of orifice, variable flattening of the shell, &c., being 

 common to each of the several sub-groups above-mentioned. 



* ' Die Foraminiferen des Septarienthones von Pietzpubl,' 4to, Berlin, 1870. 



t ' Elemente der Geologie,' 8vo, Leipzig, 1883. 



X The recognition of these difficulties evidently led Dr. Goes to compile the valuable 

 lists in his paper on " The Eeticularian Rhizopoda of the Caribbean Sea," K. Svenska 

 Votcusk.-Ak. Handl., xix. 1882. 



