226 THE VOYAGE OF H.M.S. CHALLENGER. 



the existence of Norman's genus when, in 1875, he founded his genus Bursalina for 

 a species which appears to be identical with Quasillina hrevis ; he does not venture upon 

 a generic diagnosis, and, unfortunately, gives no spicular measurements. 



Vosmaer ^ has given a discussion of the genus and species, and 

 has also given some description of the minute anatomy. His 

 specimens seem to have been in much better condition than the 

 Challenger ones. There can be no doubt that the body is not hollow 

 in life, but the soft internal tissues generally shrink up and disappear, 

 or liquefy and run off, after the death of the animal, thus giving 

 „ ,„ ^ ,„, , to the sponge its characteristically hollow form. 



Fig. 10. — QimsiUtiia brevis, J. o j 



thl^'SimT^Nat'Tize^ '^^^ commou cxistencc of a single osculum at the summit of the 



sponge {vide woodcut, Fig. 10, o), a point of considerable interest, is 



demonstrated by the Challenger specimens. (Vosmaer states that he " never saw an 



opening on the top larger than those where the sea-water enters," but there can be no 



doubt that in life there is always an osculum at the summit of the body.) 



Quasillina hrevis, Bowerbank, sp. 



1861. Eiiplectella brevis, Bowerbank, List Brit. Marine Invert. Fauna (Brit. Assoc), p. 71. 

 1864. 1 Polymastia rohusta, Bowerbank, Men. Brit. Spong., vol i. pp. 178, 28.5, pi. xxix. 



fig. 358.2 

 1866. Polymastia hrevis, Bowerbank, Mon. Brit. Spong., vol. ii. p 64 (see also vol. iii. p. 25, 



pi. xi. figs. 1-9 and vol iv. p. 31). 

 1869. Quasillina hrevis, Norman, Last Eept. Dredg. Shetland Isles (Brit. Assoc. Rep. for 1868), 



p. 329. 

 1875. Bursalina muta, Schmidt, Jahresb. d. Comm. wiss. Untersuch. d. deutsch. Meere, Jahrg. ii., 

 iii. p. 116. 



The Challenger obtained fourteen specimens of this very remarkable sponge, nearly 

 all attached to pebbles by a stem or peduncle, and all from Station 49. Many of the 

 specimens have a single small osculum at the summit [vide woodcut. Fig. 10, o) ; all 

 appear to be hollow, containing in the large internal cavity more or less of a yellow 

 amorphous substance caked on to the body-walls. The spicules are, as usual, large and 

 small styli, the former measuring about 1-1 by 0*02 mm. and the latter about 0-28 by 

 O'Ol mm.; they agree very fairly with those of Bowerbank's species, as shown by his 

 preparations in the British Museum. 



It is doubtful whether the sponge described and figured by Schmidt ^ from the Gulf 



1 Sponges of the " Willem Barents" Expedition, 1880 and 1881, p. 20. 



2 There has evidently been some mistake here, we give this synonym because fig. 358, pi. xxix. vol. i. of Bower- 

 bank's Mon. Brit. Spong. is described in the first volume (pp. 178, 285) as Polymastia rohusta, but is referred to in the 

 third (p. 25) and fourth (p. 31) volumes as Polymastia brevis. 



' Spong. Meerb. von Mexico, p. 70, pi. x. fig. 4. 



