LAGENIDA. 37 



The chief variations from this central type depend upon alterations in the nature of 

 surface-ornamentation, or the shape, length, and direction of the neck. We are fully 

 convinced that there is no true specific division determinable from these characters, either 

 among the costate group above indicated, or even in the much wider range of Lagena 

 in general. The division of the genus into Ectbsolenian {Lagend) and Entosolenian 

 {Entosolnid) groups, adopted by Professor Williamson, in his Memoir on the Lagence, 

 and in his Monograph, whilst it might afford us some general assistance in classifying a 

 bulky list of varieties, seems only to lead into greater difficulties, for we find that the 

 principal forms may be traced in series from the pear-shaped body, with the long, thick- 

 lipped neck, through every gradation of shortening, and eventually of intussusception. 

 But if the distinctions founded on contour be thus open to objection, still less dependence 

 is to be placed on the shape of the aperture, for systematic purposes. There can be little 

 doubt that the typical form of the aperture, if we may judge from the finest and most 

 fully developed specimens, is very similar to that of the Polymorpldnce and Nodosarince, a 

 circular orifice surrounded by radiating lines. The radiation is only to be observed in 

 exceptional specimens ; but the majority of tlie Lagence preserve the circular form of 

 orifice. In the feebler varieties, especially those which have no neck, there is a tendency 

 towards an oval form of orifice, and in the flattened specimens grouped as L. marginata 

 the typical round mouth is represented by a mere slit. Professor Reuss has divided his 

 family Lagenida into two genera, Lagena and Fissurinn, on these peculiarities. It has 

 been reserved for Professor Seguenza to carry subdivision to an extreme. He recognises 

 no less tlian eight " genera" of Lagenida, namely, Ovulina (shell oval, aperture circular), 

 Phialina (shell oval, aperture at the top of an elongated tube), Aiiijjhorina (shell fusiform, 

 aperture circular), Tetragonulina (shell square and tubulated, aperture circular), Flssurina 

 (shell compressed and equilateral, aperture in the form of a slit), Amygdalina (shell com- 

 pressed and inequilateral, aperture slit-like), Trigonulina (shell triangular, aperture slit- 

 like), and, lastly, Obliquina (shell twisted, aperture circular). 



We need not say that with such a generic subdivision we have no agreement ; and 

 still less, if it were possible, with his list of new species — an example of hair-splitting to 

 which we know of no parallel in systematic zoology. Of the 102 "new species" of Lagena 

 described in his memoir, there may, perhaps, be foiu' or five undescribed forms worthy of 

 subvarietal names; the rest are ordinary specimens of well-known forms, long since 

 described. If the system pursued by the Italian professor were to be followed, it would 

 soon become necessary to describe and name every individual specimen. 



As we have before stated, the situation of the general aperture in relation to the body 

 of the shell is exceedingly open to variation, even in groups of specimens identical in their 

 other characters. We find in rare examples, under similar limitations, another complicity 

 in the classification, arising from the occurrence of an orifice at each end of the shell. This 

 peculiar development may be traced through the " caudate" varieties of the various forms ; 

 and, as all the feeble Lagence, especially clear-shelled and slightly striated individuals, have 



