ON THE GENUS POLYMORPHINA. 209 
commend itself to a second observer. The first name is used for a mixed lot consisting 
partly of eompact fusiform Polymorphine, the remainder of doubtful Nodosarine. His 
genus Rostrolina, on the other hand, consists entirely of Polymorphine ; and its diagnosis 
is based upon the characters of the last chamber, especially its produced extremity and 
arcuate or slit-like terminal orifice. We have not pretended to sort the whole of the 
figures of the Polymorphinæ contained in Herr von Schlicht's work, but have inserted 
references to the least doubtful of them in their proper places. 
In the subdivision of this truly polymorphie genus we are dependent on certain con- 
stantly varying characters, and the specific (or rather varietal) names we have adopted 
are those which have been given to forms which represent the best-defined lines of de- 
parture from a central type. We are well aware that many Continental observers, with 
their inclination towards minute and nominal distinctions, may regard some of the groups 
associated under a single varietal name as embracing too wide a range in minor cha- 
racters; and we can only offer in defence the fact that we have in no case ignored a 
published trivial name that we could make of the slightest service in defining any par- 
ticular assemblage of forms; and regarding the arrangement we have adopted as suffi- 
cient to embrace every modification of the type that has come under our notice, we 
could not have carried the process of subdivision further without naming almost every 
specimen. 
The characters most available for purposes of systematic description are those depend- 
ing on the shape, number, arrangement, and “ setting on ” of the chambers, and the con- 
dition of the surface of the shell in respect to ornamentation. In M. D'Orbigny's first 
scheme of classification of the Foraminifera *, whilst the type was still only known by 
its smooth varieties, the genus was divided into four subgenera, which are given with 
their characters as under:— | 
PoLYMORPHINA (proper), having a large number of chambers visible, alternating upon 
two sides almost equally. 
 GurrULINA, having but few of the chambers visible, alternating upon three faces; cham- 
bers embracing. 
GLOBULINA, alternating on three faces, chambers embracing; three chambers only 
visible. 
PYRULINA, alternation irregular, or somewhat obscurely spiral, formed of half-em- 
bracing chambers. > 
These subgeneric names have been accepted with more or less reservation by subsequent 
continental writerst. But when a subdivision of this sort has confessedly no natural 
basis, it is fair to judge it on the simple issue of convenience as an artificial arrangement ; 
and it has been thought better to abandon the complication of terms it necessitates, as 
tending to confuse rather than to simplify a general scheme of the group. 
+ “Tableau méthodique de la classe des Céphalopodes."— Annales des Sciences Naturelles, Tome 'T*"*, 1826 
+ Quite recently Herr Karrer has abandoned the subdivision into subgenera, as Prof. Reuss also appears in some 
measure to haye done. 
