SPONGES FKOM THE ABROLHOS ISLANDS. 489 
system is already of the leuconoid type. The large oxea are confined to the 
dermal cortex, where they form a well-defined layer, and have not yet invaded 
the chamber layer as in L. australis and, to a less extent, in L. antiqua. 
There are other minor differences distinguishing L. nipponica from either of 
the Australian species, but the material in our possession is not sufficient to 
elucidate all these. 
It is clear that Lelapia antiqua is intermediate in structure between the 
more primitive L. nipponica and the less primitive L. australis, and it is 
interesting to note that it also occupies an intermediate position geographi- 
cally, L. australis having been found so far only off the Victorian coast. 
Register No. aiui Locality. VII. 1 e, Sandy Isle. 
11. Dekcitopsis minor Bendy [1916 B]. 
There is one specimen in the collection. The sponge, which measures 
42 mm. in length, 25 mm. in breadth, and lias an average thickness of 7 mm., 
forms an irregular, oval, cushion-like mass, concave below, and probably grew 
on the back of a crab. The margins are broadly rounded. The surface is 
smooth and minutely punctate. The vents are small and few in number, 
scattered singly over the upper surface. Inhalant pores are closely scattered 
over the surface. Colour of surface in spirit varying from light brown to 
dark slate-grey, internally dull yellow ; texture firm and compact. 
The skeleton consists of a dense feltwork of loose spicules irregularly 
arranged except at the surface, where there is a dermal layer of perpendicu- 
larly arranged oxea. The spiculation agrees closely with that of the type. 
The ectosome and choanosome are not sharply differentiated, but the 
former contains many more spicules. There is no fibrous tissue in the ecto- 
some. The mesogloea of the choanosome is finely and uniformly granular. 
The dermal pores lead into short inhalant canals, which penetrate the ecto- 
some and lead into large crypts from which the inhalant canals of the 
choanosome originate. The canal system is diplodal, not eurypylous as 
described for Dercitopsis ceylonica Deudy. The flagellate chambers are large 
and pouch-like, with a short wide aphodus and a short narrow prosodus ; 
they measure about 0'04 mm. in longer diameter. The exhalant and inhalant 
canaliculi of the chambers are lined by flattened epithelium, the nuclei of 
which can be seen. The collared cells are apicinucleate. Small round 
testes are scattered in the deeper parts of the choanosome, in which 
spermatogenesis is clearly shown. Tailed spermatozoa are present. There 
is no trace of ova, so the species is probably dioecious. 
Previously known Distribution. Indian Ocean {^Dendy). 
Register No. and Locality. IT. 1, Wooded Isle. 
12. Dercitopsis mammillaris {Lendenfeld} . 
Plakinastrella mammillaris Lendenfeld [1906]. 
Dercitopsis inammillaris Dendy [1916 B]. 
The single specimen is of depressed cushion-like form, and has apparently 
been attached by a broad base to the vertical side of a rock, for two large 
