Mr. H. J. Carter on the Polytremata. 213 



or ends of pillars of support in foraminated groundwork ; h h, un- 

 foraminated linear areje uniting the same ; i, larger dimples or 

 circular arese, foraminated in the centre and surrounded by an 

 unforaminated ring; k, subhexagonal or polygonal unforaminated 

 reticulation, with foraminated interstices; /, fine linear (tuljular ?) 

 network in centre of unforaminated reticulation ; m m m, thx'eads 

 composed of an agglomeration of sand, siliceous spicules, and 

 other minute objects, connected with the apertures and with 

 each other ; n n n, spicules projecting from the apertures of 

 the entire branches; ooo, the same, projecting from apertures 

 formed in the ends of the branches broken off; p, triradiate 

 spicule arrested in an aperture ; q, purple spicule of a Gorgonia ; 

 ?• ?•, globo-stellates of a Compound Tunicated animal; ss, dried 

 pseudopodia ; t t, cancellated structure of interior ; vvv, cavities 

 in the same, containing spicules chiefly in a fragmentary con- 

 dition. 



Fiy. 7. Polytrema halaniforme, C&riQX (Carpenteria, Gray), on a valve of 

 Mytilicardia caJijctdata, nat. size : a, a, apertures. 



N.B. For good illustrations of the test of this species, see 

 Carpenter, ' Phil. Trans.' 1860, vol. cl. pt. 2, pi. xxii. figs. 1 and 

 5-15 ; also ' Introduction to the Study of the Foraminifera,' 

 18(32, pi. xxi. figs. 6-18, but not so well executed. 



Fiff. 8. The same. Supposed embryo, about l-92nd inch long : a, apex ; 

 b, base ; c, chitinous integument, micro-granulated ; d, large 

 spiral aperture ; e e, small papillary apertures ; /, one of same, 

 from which a minute filament of foreign substance is projecting ; 

 ^, internal cavity, surrounded by opaque granular material, ap- 

 parently in pouch-like cavities. Scale about l-12th to l-8.30th 

 of an inch. 



Fiy. 9. The same, embryos of (?), on fragment of cancellated cavity 

 from near circumference : «, lobed form, l-332ud inch in dia- 

 meter ; b b b, iinlohed smaller forms. Scale l-12th to l-8.30th 

 of an inch. 



Fiy. 10. The same. Sponge-spicule ; new form of bihamate or fibula, 

 from among spicules of the interior, l-250th inch long. Lower 

 end restored. 



Fiy. 11. Polytrema ntriculare, u. sp., group of three individuals, nat. size. 



Fiy. 12. The same, superior view, magnified: «, utricular bodies; bbb, 

 apertures ; c, polygonal reticulation of surface. 



Fiy. 13. The same, lateral view, magnified : a a a, apertures at the ends 

 of neck-like prolongations of the tests respectively. 



Fiy. 14. The same, basal view, from which the sarcodic (now chitinous) 

 layer at once of occlusion and attachment has been removed, 

 showing -.—a a a, cavities of the three individuals respectively, 

 each of which is filled with fragments of spicules, as represented 

 in J ; c, wall at base of test, showing relative position and size 

 of polygonal reticulation and foraminated layers respectively ; 

 d, apertures on internal aspect of foraminated layer ; e, sarcodic 

 (now chitinous) layer lining the utricular chamber and prolonged 

 into the aperture — reflected. 



Fiy. 15. The same, fragment of sm-face, magnified, to show, «, polygonal 

 reticulation, and, b, foramina at the bottom of the interstices 

 respectively. 



Fiy. 16. The same, vertical section of wall of test, to show relative 

 position and size of polygonal reticulation, a, and foraminated 

 layer, b. 



