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Mr. H. J. Carter’s Contributions 
respectively characterizing these echinated sponges, as seen 
between Trikentrion Iceve and T. muricatum, the latter resem¬ 
bling in its structure that density and hardness which seems 
to me, as before stated, to exclusively belong to some of the 
Echinonemata, while the looser structure is common to all 
orders of the Spongida. 
Latruncula corticata , n. sp. (PL XXVII. figs. 1-4.) 
Erect, solid, lobate, covered with a thin chondroid dermal 
layer, apparently (the point of attachment having been broken 
off) subsessile (PI. XXVII. fig. 1). Colour now yellowish 
white. Texture chondroid on the surface (fig. l,a); reticulated, 
stiff, gum-like internally (fig. 1,5). Surface smooth as varnish 
to the unassisted eye; but under the microscope presenting 
the pointed ends of the skeleton-spicules in groups, just pro¬ 
jecting beyond the chondroid layer, which is papyraceous in 
thinness (fig. 2, b). Pores between the groups, now l-1200th 
inch in diameter and about l-333rd inch apart (fig. 2, a). 
Vents not seen, chiefly on account of the imperfect state of 
the specimens. Internal structure fibroreticulate, stiff, ar¬ 
ranged so as to present a plumose apprearance; fibre com¬ 
posed of the spicules of the species held together by the now 
dried, glutinous sarcode. Spicules of two kinds, viz. :—1, 
skeleton-, acerate, curved, smooth, sharp-pointed gradually, 
l-60th by l-4000th inch in its greatest diameters (fig. 3); 2, 
flesh-spicule, stout, straight or crooked (subspiral), spined, 
1-857th inch long (fig. 4) ; spines grouped at the ends and 
on the shaft in two places respectively at ecpial distances from 
each other (fig. 4, a), or dispersed more or less generally over 
the shaft (fig. 4, 5), or subspirally, giving the flesh-spicule a 
crooked form (fig. 4, c). Skeleton-spicules mixed with the 
flesh-spicules in the interior, the latter most abundant on the 
surface. Size of the largest specimen 3 x 2| inches. 
Hob. Marine. 
Log. Red Sea (so stated by the dealer). 
Obs. Examined in the dried state. There are three frag¬ 
mentary specimens of this sponge in the British Museum, 
which look as if they had all come from the same mass. 
Each bears my number 359 E, h, 23, and the register 
numbers 40. 5. 6. 56-58. Its generally stiff consistence, 
rendered flexible by soaking, makes it look very much like 
one of the Gumminida ; while the transitionary forms of the 
flesh-spicule (fig. 4, a, 5, c) show how the shaft may be spiral 
like that of the spinispirular, or straight like that of the 
sceptrella, whose typical forms respectively will be pointed 
out hereafter. 
