CALOAREA. 49 



« 



packed with about a dozen grains (k) of one colour and one odd one (b) (nucleus, 

 nucleolus ?), which stains a different shade. The outer sheath of cells each has a small 

 nucleus (e) and minute nucleolus (/). This sheath appears in some cases to surround 

 the inner cell entirely, and in other cases only to surround the outer part, and not to 

 exist between the inner cell (g) and the other half (a) of the ovum. 



It is possible that the smaller half of the ovum may be a feeding cell, supplying 

 nourishment to the larger half. The hyaline sphere of grains may be food material. 



In the ovum of Megapogon raripilus, the smaller half has a somewhat different 

 appearance, which suggests that it is made up of several concentric sheaths of cells 

 round a central one. These ova, however, are not well enough fixed to repay detailed 

 examination. 



REFERENCE LIST OF MEMOIRS CITED. 



1 . MiNCHiN, E. A. — A Treatise on Zoology. Edited by E. Ray Laakester. Part II. The Porif era and 



Coelentera. Chapter III. Sponges, by E. A. Minchin, M.A. 1900. 



2. Dendt, K.— Studies on the Comparative Anatomy of Sponges. V. Observations on the Structure and 



Classification of the Calcarea Heterocoela. Q. J. M. S., vol. 35 (1893), pp. 159-257, PI. X.-XIV. 

 New Series. 



3. Habckel.— Z^Jfi KalhscMvdmme. Berlin. 1872. 



4. PoLBJAEFF. — Ghallenger Rep. VIII. 1883. 



5. Bkeitfuss.— Zool. Jahrbuch, Syst. XI. (1898.) 



6 Lendenfbld, R. vok. — Die Spongien d&r Adria. I. Die Kalkschwamme. Zeit. f. wiss. Zool. LIII. 



(1891.) pp. 1-212. 



7 Dbndt a. Synopsis of Australian Calcarea Heterocoela .- with a proposed classification of the group and 



descriptions of some new genera and species. Proc. Roy. Soc. of Victoria. Vol. V. (1892), pp. 69-116. 



Minchin, E. k.—The Characters and Synonomy of the British Species of Sponges of the genus Leucosolenia. 

 Proc.'zool. Soc. Lond. 1904, Vol. ii., p. 349. 



8 



2 2 



