CALCAREA. -l!) 



packed with about a dozen grains (/) of one colour and one odd one (/>) (nucleus, 

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

 nucleus (c) 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 (//) and the other half (n) 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 lias 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. MINCHIX, E. A.. A Treatise on Zooln</y. Edited by E. Ray Lankestrr. P:irt II. Tin- PoHlVra ;ind 



I'uelrntiTa. Chapter III. Sponges, by E. A. Mincliin, M.A. limn. 



2. DENDY, A. Studies on tfie Comparative Anatomy of Spongas. V. Observations on tin- sinu-tuiv and 



Classification of the Calcarea Heterocoeln. Q. J. M. S., vol. :>'> (is 1 .):',), pp. 159-257, PI. X.-,\JY. 

 New Series. 



3. HAECKEL. Die Kallcschwiimme. Berlin. 1872. 



4. POLKJAEFF. C%?fo/^r Rep. VIII. 1883. 



5. BIIEITFUSS. Zool. Jahrbnch, Syst. XI. (1898.) 



6. LENDENFELD, R. VON. Die Spungien tier Adria. I. Die Kalksehwamme. Zeit. f. wiss. Zool. LIT I. 



(1891.) pp. 1-212. 



7. DENDY, A. Synopsis of Atmtrtilin/i I'lil-nrfu Heterocoela; trill/ // /ini/m.^n/ <-lii*xiiii-iitinn <>f ///////(////( H/H/ 



ilfxi-riptions ofsomp n/'ir ijeneni an/I species. Proc. Roy. Soc. of Victoria. Vol. V. (1*'.I2), pp. C'.i-lld. 



8. JfiNCHiN, E. A. The Charartermiml ^/jnonoinij of the British fyrdi-s <>/ ,s//i*////c.s- t>f tln'in-n us 



Proc. Zool. Soc. Lond. 1904, Vol. ii., p. 349. 



2 2 



