REPORT ON THE CALCAREA. 37 



tendency towards sagittal differentiation, and the rays of the larger triradiate spicules 

 being of still greater dimensions and rather stouter. They attain the length of 0"5 mm. 

 with a diameter of 0'06 mm. I do not think that these differences would justify the estab- 

 lishment of a new variety. 



Hitherto Leucosolenia lamarckii has been found only in the Atlantic ; its distribution 

 is now extended into the Pacific. 



Colour. — White. 



Habitat. — Station 163a, June 3, 1874 ; off Port Jackson, Australia; depth 30 to 35 

 fathoms ; rock. 



Leucosolenia blanca, Miklucho-Maclay, sp. (PI. I. fig. 2; PL III. fig. 3). 



Guancha blanca, Miklucho-Maclay, Jenaische Zeitschr., Bd. iv. p. 220, 1868. 

 Aseetta blanca, Hseckel, Kalschwaimno, Bd. ii. p. 38. 



No auloplegma-forms of Leucosolenia blanca had previously been observed with 

 well-developed peduncle. Miklucho-Maclay (loc. cit., p. 223) states that the Sponge can 

 occasionally sink down instead of growing upright, and extend upon the ground in the 

 form of a bolster. Such bolster-like specimens are the only colonies presenting the 

 auloplegma-form, but their peduncles become rudimentary. Now both the specimens 

 of this species collected by the Challenger, although without any trace of the osculum, are 

 provided with a peduncle one and a half times as long as the longitudinal axis of the 

 colony itself. Taking into consideration that the specimens observed by Miklucho were 

 found in shallow water, whde those of the Challenger Expedition, on the contrary, were 

 dredged up from the depth of 450 fathoms, and further, that while no colonial specimens 

 of Miklucho-Maclay exceeded 3 to 4 mm. in length, and 1"5 to 2'5 mm. in diameter, the larger 

 Challenger specimen is 25 mm. long, with a broadest diameter of 15 mm. ; taking all this 

 into consideration, I think it very probable that the typical Leucosolenia blanca belongs 

 to the comparatively deep-water forms. If this could be proved, the possession of a 

 solid peduncle might be used as a generic character, and a new genus, GuancJia, estab- 

 lished amongst the Asconidse. This conjectural genus would consist of Leucosolenia blanca, 

 presenting a transition form to the sessile Asconidse, of the species described by 

 Metschnikoff, 1 and characterised by the horn-shaped triradiate spicules in the peduncle, 

 and of my Leucosolenia challengeri. 



Future investigations will decide the question, and meanwhile I establish for my two 

 specimens a third variety with the following diagnosis : — 



Leucosolenia blanca, var. bathybia (PI. I. fig. 2). — Basal ray of the triradiate spicules 

 not more than 1'2 to 1*5 times as long as lateral rays. 



1 Spongiologische Studies, Zeitschr. f. wiss. ZooiL, Bd. xxxii. p. 361, 1879. 



