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



apertures, respectively marginated by an inflated round rim 

 extended upwards on one or two sides opposite into the form 

 of a lip or lips, so as to present en profil a serrated or cock's- 

 comb appearance (fig. 6). Colour coral-red or pink. Surface 

 uniformly even, except where interrupted by the brandies, 

 whose apertures (fig. Q^ccc) in many instances are more or 

 less filled with sponge-spicules entire and fragmentary, together 

 with grains of sand and other minute objects, forming a mass 

 which is continuous with strings of the same material exten- 

 ded in an irregular network between the apertures generally 

 (fig. 6, m m m) ; which network is frequently intersected by 

 the most delicate, straight, cobweb-like threads, the remains of 

 dried pseudopodia (fig. 6, s s). Presenting a variety of surface- 

 patterns according with the age of the structure, locally and 

 generally, viz. : — at first, or in the earliest period, a foraminated 

 groundwork in Avhich there may be a few unforaminated 

 dimples or depressions (fig, Q,g g g) ; then the dimples may 

 be united by limited,branchedjlinear, unforaminated areffi,some- 

 what narrower than the foraminated part, so as often to present 

 together a submeandriniform appearance (fig, 6, ^ ^) ; or the 

 dimples may be expanded into circular foraminated arese, sur- 

 rounded respectively by an unforaminated ring, the whole 

 being set in a foraminated groundwork (fig. 6, i) ; or, lastly, 

 over the thickest parts of the fully developed test, the fora- 

 minated groundwork may give place to a subhexagonal or poly- 

 gonal unforaminated reticulation, whose interstices only are 

 foraminated (fig. 6, h). Internal structure cancellous in appear- 

 ance, but originally consisting of subconcentric (imbricative 

 or eccentric) foraminated laminge supported on detached hollov) 

 pillars, whose positions respectively are for the most part indi- 

 cated by the *' dimples " and circular depressions externally, 

 each lamina thus forming a continuous cavity between itself 

 and the next following inwards, like the roof and pillars of a 

 crypt (fig. 3). Presenting, in horizontal sections at different 

 distances from the base, subconcentric layers diminishing in 

 number towards the truncated neck ; and in a vertical section, 

 the same in a conical form, interrupted above at the truncation 

 of the neck. Finally [i. e- in the old state) losing the fora- 

 minated portion of the lami na except on the surface ; the sub- 

 hexagonal network alone remaining internally, which, together 

 with the hoJlow pillars now become solid, forms a continuous 

 netted mass or labyrinthic reticulation, in which it becomes 

 difficult, for want of the foramination, to trace the subcon- 

 centric layers inside the surface-one (fig. 6, e, ^i). Cavernous 

 dilatations or cavities of the internal structure (fig. 6, i' v ??), in 

 continuation with each other, exist about the axis of the spe- 



