218 FAMILY GLOBIGERINIDA. 



portion being about two-thirds ; though we occasionally meet with specimens in which the 

 disk is unusually large and the length of the spines does not equal more than half its 

 diameter, and others in which the disk is unusually small and the length of the spines is 

 equal to its whole width. In the Mediterranean Calcarina, on the other hand, I have 

 seldom met with more than nine spines ; and any excess beyond that number is only 

 presented by specimens in which the disk is very large, so that wide intervals present them- 

 selves along its margin between the bases of the spines. Their spines are nearly always 

 simply clavate in form, any tendency to bifurcation or trifurcation at their extremities being 

 rare ; and they show but little disposition to increase in length with the enlargement of the 

 central disk, being often not only relatively but even absolutely shorter in old specimens ; as 

 if the spines had entirely ceased to grow, and the disk had (as it were) included their basal 

 portions within itself. In some instances, indeed, they scarcely show themselves enough to 

 attract attention ; being little more than tubercular projections from the margin of the disk 

 (Fig. XXXV, h). Notwithstanding, however, this strongly marked difference in general 

 physiognomy, it becomes obvious, on the comparison of a sufficient number of individuals, that 

 no line of specific distinction can be fairly drawn on such a basis between the Philippine and 

 the Mediterranean forms ; since among the Philippine we meet with numerous specimens in 

 which the spines are as few and simple as they are in the great bulk of the Mediterranean 

 (Fig. XXXIV, B, c) ; while specimens not unfrequently present themselves among the 

 Mediterranean, in which there is not merely an addition to the ordinary number of the 

 spines, but a manifest disposition in many of them to subdivide near their extremities, thus 

 showing an obvious approximation to the Philippine type. Although the spines usually 

 radiate nearly in the equatorial plane, yet it becomes obvious, when their connexion with the 

 central disk is examined, that they originate at different levels (Fig. XXXV, e, f) ; this will 

 presently be found to depend on the turbinoid form of the spire (^ 383). Besides 

 the ordinary radiating spines, an extraordinary growth of short pointed spines is sometimes 

 seen, either partially or completely covering one or both surfaces of the central disk (Fig. 

 XXXIV, g) ; and examples occasionally present themselves (Fig. XXXIII, a), in which 

 the development of these seems to have altogether superseded that of the ordinary radiating 

 spines. 



380. It is remarkable that among the very young specimens of this type, a yet greater 

 variety shows itself than among those further advanced in life. At Fig. XXXIV, a, b, c, is 

 shown what may be considered the ordinary or normal aspect of the young Calcarina ; whilst 

 in Plate XIV, figs. 6, 7, we have a representation (under higher magnifying powers) of an 

 example of what may be termed the hispid condition, which so frequently presents itself in 

 small CalcarincE as to give rise to a question whether they should not be made to constitute a 

 distinct species. I have satisfied myself, however, by the comparison of a large number of 

 specimens, that so continuous a gradation presents itself between the smoothest and the most 

 hispid specimens, as to render the attempt to separate them specifically altogether futile; and 

 Mr. Parker, who has examined a yet larger number of specimens, fully confirms this con- 

 clusion. Moreover, the internal structure of these hispid specimens shows no departure 

 whatever from the ordinary type. 



