tie Oscules of Cinaclijra. 663 



fringe of needles rising above tlie general surface; on the 

 upper part of the surface are smaller orifices, likewise 

 surrounded by a spicular fringe 



Sollas (9, pp. XXXV, 27) regarded tlie flask-shaped recesses? 

 as being either vestibules or cloacas, though he failed to find 

 any structural differences in them, and for convenience of 

 description he called them all oscules. The smaller orifices 

 and pits near the summit were considered to be young 

 undeveloped vestibules and cloacas of the same kind as those 

 on the rest of the surface. 



The good state of preservation of numerous specimens from 

 the Antarctic has enabled me to clearly distinguish two kinds 

 of depressions — vestibular and cloacal ; and later I was able 

 to note the same distinction in the ' Challenger' specimens. 



Cinachyra barhata in its adult condition (PI. XIV. fig. 1) 

 shows three zones : — (!) a basal root-tuft zone ; (2) a broad 

 " equatorial" zone of poral vestibules; and (3) a superior or 

 "polar-" zone of oscules («e«s?« sinc^o). In good specimens 

 these zones are clearly obvious to the naked eye, for the 

 surface pile of spicules is higher and looser in the poral than 

 in the oscular zone and slopes downwards ; the pile in the 

 oscular area is shorter and denser and points vertically 

 upwards, presenting, in fact, a stubble-like appearance. 



The orifices of the poral vestibules are usually wide open, 

 though even large ones may be closed; but in almost every 

 instance the oscules are tightly shut, the marginal fringes 

 being closed over them in the form of conical stacks. 



The shape of many of the specimens from Kerguelen is 

 oval and the poral zone and oscules are arranged obliquely 

 to the long axis. Often, too, at first sight no trace of oscular 

 fringes or oscules is apparent ; but by rubbing off the surface 

 pile at the superior end of the body, so as to leave a tonsure- 

 like patch, the oscules become visible as minute dark pin- 

 points on the surface (PI. XIV. fig. 3). 



Prof. Sollas has given such a full account of the poral 

 vestibules that there is no need to say anything further 

 about them here. The oscules are few in number in com- 

 parison with the vestibules ; in one specimen there are seven 

 of the former arranged in an open spiral on the summit and 

 over forty of the latter. 



Usually the oscules appear as low monticules each with a 

 shallow crater-like cup, but occasionally they may be flush 

 with the surface. On making a section so as to cut vertically 

 through an oscule, usually, owing to the extreme state of 

 contraction, no passage can be seen, but simply a break in 

 the continuity of the white cortex,, the fleshy tissues of the 



