340 Mr. H. B. Brady on EUipsoidina, 



On exposing the interior of the shell, by carefully breaking 

 away the chamber- walls (fig. 4), or on mounting young and 

 transparent specimens in Canada balsam, it is seen at once 

 that the column extending from the apex of the primordial cham- 

 ber (or sometimes from within it) to the anterior of the termi- 

 nal segment bears only superficial resemblance to the neck in 

 the chambers of the Nodosarice, and is in no way its homo- 

 logue : indeed the description of it in the memoir under notice 

 is correct in most of its features. The term " tubular," as 

 applied to it, is apt to mislead 5 for although in form the column 

 is often cylindrical and hollow, the walls have almost invaria- 

 bly perforations of considerable size, and are often even split 

 up into several smaller and independent portions. Figure 5 is 

 a drawing of one of these divided into three spreading arms ; 

 and in fig. 6 the tendency to separate into several distinct 

 members may be well seen. When partaking more of the 

 cylindrical or tubular form, a high magnifying-power and 

 careful regulation of the light will generally show the existence 

 of perforations, longitudinal and slit-like, from which it may 

 be inferred that the column consists of delicate lines of shell- 

 substance associated in perpendicular bundles. This conclu- 

 sion is further strengthened by the frequent occurrence of 

 surface-irregularities running in the same direction, ^^^hen 

 the column takes the common and more or less tubular form, 

 its apex is usually swollen at the point where it joins the en- 

 veloping chamber, whilst nearer the base little, if any, altera- 

 tion in diameter is observed ; in some instances it tapers regu- 

 larly down to the point of junction with the inner chamber. 



The shell-wall is not, as a rule, perforated at either the an- 

 terior or posterior extremity within the walls of the column. 

 In the exceptional cases in which an orifice occurs in the por- 

 tion of the chamber-wall corres]3onding to the upper end of a 

 segment of the central column, it may or may not form the 

 channel of communication. But the function of the central 

 body is not that of a stoloniferous tube ; and when it performs 

 this ofiice (if ever), it arises from casual irregularity in groAvth. 

 The pui-pose which it serves is, I believe, purely that of a sup- 

 port for the chambers, which are othei-wise so lightly held 

 together that the slightest shake would separate them. The 

 adhesion between the posterior portions of the chambers is 

 scarcely perceptible, and amounts to little more than the mere 

 juxtaposition of surfaces. If Professor Seguenza's figures be 

 drawn from perfect sjDecimens, and not from such as have had 

 the outer chamber broken away, it would follow that the sup- 

 port is formed before the enveloping chamber. The form of 

 the column and its relation to the shell make it improbable 



