M.OARRA. 15 



Spicules (Pig. 

 Tin- //./'/ ipicuU* are of one sort :-- 



i It. .jul.u triradiataL . Rays straight, very slender, parallel, bluntly pointed, 

 140M to 200 n long x 4* to ?M thick. Ratio of length to tliirknew, 

 to 40. 



The Oscular spicults are of one sort : 



(k) Mate triradiates, strongly folded. Basal ray straight, nearly parallel, 

 bluntly pointed, 55 p to 90 M long x 1 it. to SM tliick. Paired rays nearly 

 straight in facial view, and twice bent when viewed parallel to the basal 

 ray. Tapering, moderately sharply pointed, 90 M to 140/* long x 8 M to 

 10 M thick. Oral angle 105 to 115. Angle of fold 110. 



LEUCANDRA KRIGIDA. 

 (Plate XXVII., Fig. 6, and Plate* XXIX. and XXX., Figs. 35-40.) 



Thi-re are eleven specimens of this new species in the collection. They are all fig- 

 shu|H-.l, \\itli the oscule at the thick end (see Fig. 6). The surface is smooth, pure white 

 and rather chalky in appearance. They vary in size from 10 mm. x 3 mm. to 

 30 mm. x 10 mm. (nee Fig. .15). They are all solid to the touch, though they vary 



much in texture when cut open. All but one of the specimens have the osculc 

 completely closed, and its presence is only indicated externally by a slight 

 protuberance. One specimen, 21 mm. long x 7 mm. diameter, has the osculc open ; it 

 is 2 mm. in diameter,* and is surrounded by a short spiculated membranous collar (see 

 Fig. 39). 



Tlu- canal .system varies considerably in the different Kpecimens ; in some there it* 

 .1 wide gaatral cavity with large branching canals opening into it, while in others there 

 is no gastral cavity, the excurrent canals all converging to the oscule. In cross-section 

 tlu- >JM-. iiiH-as differ less than might Iw expected, for the gastral cavity appears to lie 

 divided by delicate septa, which give the whole section a mesh'work appearance even 

 when longitudinal sections show a large cavity. 



The excurrent canals are usually surrounded with a fairly distinct skeleton of 

 Iri radiates, among which are a few quadriradiates. 



The incurrent canal system is made up of a series of very irregular spaces leading 

 from the surface into the rather more regular longitudinal canals ; these run parallel 

 to the excurrent canals, from which they may Ite distinguished by their lest* 

 pronounced skeleton, which never contains quadriradiates. 



The bulk of the skeleton consists of regular triradiates ; the quadriradiates round 

 the gastral cavities and excurrent canals are very constant in size. In some specimens 

 tin -y arc so rare that they can only be found with great difficulty. The apical rays, 

 which are slender and crooked, project into the canals. 



VOUIT. 2 K 



