On Species q/'Squamulina and Difflugia. 32o 



pointed. Otlierwise it much resembles EugJypha. Nor does 

 the sudden retraction of tlie animal by means of the 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. 



Fif/. 1. Squamidiiia scapula, natural size. 



Fit/. 2. The same, full-grown test<», magnified five times : a, inclined posi- 

 tion. 



Fi(/. .3. Tlie same, full-prowTi test, 1-lotli of an inch long, greatly magni- 

 fied, to show structure and cavity : «, pedestal ; b b b, column ; 

 c, body ; d, neck ; e, head; ff, brush of spicules ; f/, triradiate 

 spicule of Grantia ciliata (calcareous) ; h, tritid spicule of I'a- 

 chymatismai?) ; tj/, dotted line indicating shape and size of 

 chambered cavity; A, aperture; //, tentacular (■') appendages 

 of marine animals. 



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

 clusively) are drawn strictly on the scale of l-24th to 1 -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, wherein the 

 different spicules of the head are intended to represent somf of 

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

 in one specimen. 



Fiij. 4. The same, summit of pedestal, with portion of column tinincated 

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



Fiff. 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. 



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

 test has been broken ofl", 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. 



Fir/. 8. The same, pedestal with portion of column attached, broken off 

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

 divisions are continuea up into the 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 

 divi.sion3 when fresh. 



Fi(/. U. The same, direct view of the pedestal under the same circumstances, 

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



f resenting the dried animal substance, 

 he same, upper view of the pedestal, showing the chambered 

 form of the mterior through the te,st; test chiefly Inmud of the 

 fragnients of sponge-.spicules : a, aperture of the summit ; 

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

 chitinous substance. 



This specimen, which I have mounted in balsam, 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. 

 Fit/. 11. The .<;ame, lower part of column broken ofl'from the pedestal at 



Ann. iL- Mar;. X. Hist. Ser. 4. Vol. v. 23 



