202 Mr. H. J. Carter on 



this species. To say that it never goes beyond the size or 

 consistence mentioned would be premature, since there are 

 many skeletal specimens of this family from Australia in the 

 British Museum which far exceed these in dimensions as well 

 as in compactness of structure. Then it should be remem- 

 bered that the older the growing specimen is, the thicker the 

 fibre, which, 'of course, is especially seen at the base. Thus 

 in two small specimens (? of a new species), received from the 

 same source, since the above Avas written, each about 4 in. 

 long, one of which is club-shaped and the other bifurcated, 

 the fibre commences in a thick, round, furrowed, skeletal 

 stem about l-12th in. in diameter, which throws out buds 

 from its surface and ultimately branches into a dendritic 

 form to support the sarcode of the head, which is of a brown 

 colour. Why the colour should be brown in one specimen of 

 the same species and red in another, while the soft fleshy 

 fibro-reticulation of the dermis is equally charged with ?-pig- 

 raental cells in all, I am ignorant. 



Fam. 2. Aplysinida. 

 Darwinella australiensis, n. sp. 



Massive, sessile, lobate ; lobes simply convex, or com- 

 pressed and elongated horizontally into meandriniform, thick, 

 erect, and branching ridges. Consistence soft, resilient. 

 Colour, when fresh, " Venetian red," now dark grey flesh- 

 colour. (Surface conulated, conuli about l-8th in. apart, 

 terminated respectively by a single filament or fibre, which 

 gives a hairy appearance to the whole, supported in the in- 

 terval by a beautifully soft and fleshy fibro-reticulated dermis 

 charged abundantly with triradiate keratose spicules, whose 

 rays intercross and lie parallel to each other respectively, so 

 as to leave interstices in which the pores are situated. Vents 

 numerous on the prominent parts of the convex lobes and 

 along the ridges of the compressed ones. Fibrous structure 

 loose, widely reticulated ; main or vertical branches composed 

 of a thin cylindrical wall of dark amber-coloured keratine, 

 cored, as usual, with a light grey granulo-flocculent substance, 

 but with the " core " much greater in diameter than the 

 thickness of the keratose wall, so that the fibre collapses on 

 desiccation, which is the opposite to that which obtains in the 

 Luffarida ; hence this is the chief distinction. Lateral or 

 small fibre very scanty, its place being supplied by the tri- 

 radiate keratose spicules with which the parenchyma is as 

 much supplied as the dermis ; the whole traversed by the 

 branches of the excretory canal-systems which terminate re- 



