ZOOLOGICAL CONSIDERATIONS. 11 



two hands to represent the modifications (" species ") of two such parallel types of 

 ForaminiiiTa, the thumb of one hand resembles more closely the thumb of the other hand 

 than it does any other of the fingers on its own. In other words, the extreme member 

 of one series bears greater similarity to its isomorph in the other series than it does to its 

 own nearer relations, and so on through the remaining members of the respective groups. 

 Under conditions like these, artificial subdivision based upon minor morphological 

 characters is certain to infringe the order of nature, owing to its tendency in some cases 

 to separate forms closely allied, and in others to place together such as have no natural 

 affinity. 



The disposition to variation in minor characters is another point that has not been 

 sufficiently recognised, and an endless multiplication of " species," with almost hopeless 

 confusion in nomenclature, is the result. Take, as an example, a series of forms belonging 

 to the sub-order Perforata, say that of which the best central type is Nodosarina 

 (Mdrr/iniilina) raphanus. All the specimens referable to the type consist of a single 

 row of segments joined end to end ; the row may be straight, arcuate, coiled a little at 

 the base (crozier-shaped), or helicoid ; the individual segments may be rounded, 

 cylindrical, somewhat compressed laterally, much flattened, or embracing ; the general 

 aperture may be central or excentric ; the surface of the shell may be smooth or have an 

 ornamentation of parallel ribs, spines, or tubercles ; whatever the precise form of the 

 investment, the animal, so far as we know, is the same a single row of bead-like lobes 

 of sarcode, with no power to build for itself other than a perfectly simple shelly 

 covering. Between the extremes of character possible within the limits above laid down 

 every conceivable intermediate condition has been found ; and if the word " species " is 

 anything more than a conventional term, the whole ought to constitute a single species ; 

 but governed by the exigencies of a partially artificial arrangement, the modifications 

 embraced in this simple unbroken series constitute thirteen -genera or almost two entire 

 families in Professor Reuss's classification ; and how many hundreds, if not thousands, of 

 so-called "species " have been founded upon the trivial characters above enumerated it 

 would need much patience to ascertain. 



To revolutionise the present nomenclature of the Foraminifera is no part of the object 

 of this essay ; if that is ever attempted it must be from a broader standpoint than the 

 Carboniferous Rhizopod-fauna affords. It is impossible to start de novo, and it is there- 

 fore only left for us to determine what course is open to the least objection under the 

 conditions that at present exist. So far as " specific " names go, it is manifestly best to 

 accept those that represent tolerably well-marked morphological characters, even when 

 they are matters of degree and manifestly variable, but without attaching any true 

 specific value to them. The advantages of a binomial nomenclature are universally 

 admitted ; but in the present state of natural history science it is impossible to express 

 the details of zoological relationship thereby, and we must either use a trinomial or even 

 quadrinomial method of designation, or be content with names whose uniformity does not 



