OSCULA AND ANATOMY OF LEUCOSOLENIA CLATHRUS. 479 
with great accuracy, but says nothing of the oscula, though 
since he talks of ‘‘ Tarrus forms” it might be inferred that he 
had seen them. Oscar Schmidt’s work! on the development 
of this form contains no mention of oscula, 
The curious phenomenon which is usually termed lipostomy 
has always been a great puzzle tome. How can asponge exist 
without an osculum? The osculum is the central exhalent 
opening of the whole canal system, and to it converge all the 
currents which enter by the pores and flow along the canals. 
How can so important an opening be wanting? Haeckel 
attempts an auswer to the question in the case of this sponge : 
‘Tn the interior of the tubes the water goes in and out only 
by the pores.” 
Wishing to study the histology of this sponge, I was able, 
by the kindness of Sig. Lo Bianco, the well-known Con- 
servator of the Naples Zoological Station, to go with the little 
steamer “ Frank Balfour,” of the Station, in order to collect 
and preserve Leucosolenia material fresh from the sea; and in 
the very first specimen of Leucosolenia clathrus which 
came on board I saw oscula of such a size that I was perfectly 
astounded. ‘To be brief, 1 find that Leucosolenia clath- 
rus in the fresh healthy condition not only has oscula, but 
in the full-sized specimens larger oscula than any other Leu- 
cosolenia known to me, whether from pictures or in the 
flesh. 
The specimens of Leucosolenia clathrus may be for 
convenience divided into “large” and “small.” By large 
specimens I mean the big, full-grown colonies, often 10 cm. in 
length and 3 or 4. cm. in height. By small specimens I mean 
the very young colonies of 5 mm. or less in extent. Fig. 1 
represents two oscula of a large specimen seen in profile, 
natural size ; one osculum (@) is widely open, the other (4) is 
partly contracted. Fig. 2 represents three more oscula from 
the same specimen (which had altogether ten oscula), seen 
1 «Tas Larvenstadium von Ascetta primordialis und Ascetta 
clathrus,” ‘Arch. f. mikr, Anat.,’ vol. xiv, 1877, pp. 249—263, Taf, 
XV, XVl. 
