On Species o/Squamulina and Diffliigia. 325 



pointed. Otherwise it much resembles E^tglypha. Nor does 

 the sudden retraction of the animal by means of tlie three 

 sarcodal cords attached to the posterior part of its body cha- 

 racterize it as a distinct species less than the peculiar form of 

 the test. 



EXPLANATION OF THE PLATES. 

 Plate IV. 



Fig. 1. Sqummdina scapula, natural size. 



Fig. 2. The same, full-grown tests, magnified five times : a, inclined posi- 

 tion. 



Fig. .3. The same, full-o-rowu test, l-lotli of an inch long, greatly magni- 

 fied, to show structure and cavity : a, pedestal \ h bh, column ; 

 c, body ; r/, neck ; e, head; / /", brush of spicules ; g, triradiate 

 spicule of Grantia ciliata (calcareous) ; //, trifid spicule of Pa- 

 chymatisma (?) ; r«?', dotted line indicating shape and size of 

 chambered cavity; Z', aperture ; //, tentacular (?) appendages 

 of marine animals. 



N.B. This and the seven following figures (viz. 4 to 10, in- 

 clusively) are drawn strictly on the scale of l-24th to l-1800th 

 of an inch, to show their relative size individually and the rela- 

 tive size of the parts of which they are individually composed ; 

 latitude only being given to the spicular detail, wlierein the 

 different spicules of the head are intended to represent some of 

 the varieties that may be seen in many, rather than all together 

 in one specimen. 



Fig. 4. The same, summit of pedestal, with portion of column truncated 

 close to neck, to show, a, circular aperture and chitinous lining. 



Fig. 5. The same, upper portion of pedestal with part of column attached, 

 lateral view, to show chitinous lining just about the neck, un- 

 covered by arenaceous coat. 



Figs. 6 & 7. The same, disks of the pedestal left on the fucus after the 

 test has been broken off, showing the form of the pseudo-septal 

 divisions prolonged inwards from the margin, but ending short 

 of the centre, so as to leave an open area there. 



Fig. 8. The same, pedestal with portion of column attached, broken ofl 

 from the disk (dried specimen), showing that the pseudo-septal 

 divisions are continued up into tlie dome : a a, portion of animal 

 substance dried, showing, by its lobed form and position, that it 

 occupied the central area and the interspaces between the septal 

 divisions when fresh. 



Fig. i). The same, direct view of the pedestal under the same circumstances, 

 showing the same facts more satisfactorily : a, dark portion re- 

 presenting the dried animal substance. 



Fig. 10. The same, upper view of the pedestal, showing the chambered 

 form of the interior tlirough the test ; test chiefly formed of the 

 fragments of sponge-spicules : a, aperture of tlie summit ; 

 b, dried animal substance ; c c c, chambered cavities, lined with 

 chitinous substance. 



This specimen, which I have mounted in l)alsam, indubitably 

 homologizes the " pedestal" with the test of a Nautiloid Fora- 

 miniferous animal, together with the development of the "co- 

 lumn " from the initial or primary cell. 



Fig. 11. The same, lower part of column broken off from the pedestal at 



Ann. ih Mag. N. Hist. Ser. 4. Volx. 23 



