SYNCRYPTA SPONGIARUM. 309 



though "in the centre of the cells there is seen clearly in life a roundish 

 structure, probably a nucleus, or still more probably a pyrenoid.'" If the 

 material were identical, Dendy, having dealt with it only in the preserved 

 state, would presumably obtain only the conditions figured by Urban, with- 

 out evidence of the nucleus or pyrenoid described in the fresh cell. 



The resemblance of Dendy's figure to Urban's is striking, many of the 

 cells are adhering in pairs, and many (not all) of these pairs are noticeably 

 smaller than their neighbours; one pair (at '2 o'clock' of the drawing, 

 14 mm. below "ep.") shows the adpressed ellipsoid form of the twins 

 figured by Urban, the diameters of the ellipse being 4 fj, and 3/x. It is worth 

 mentioning also that in the plate ihe ratio of the diameters of the largest 

 yellow bodies lo the smallest is about as 4 : 3 : that is, about as ; 3 /2 : 1, or the 

 ratio of the diameter of a sphere to that of one of two equal spheres formed 

 from it. 



The presumption appears strong that the organism drawn by the two 

 authors is one and the same ; if so, Dendy's view that the bodies are meta- 

 morphosed collar-cells is contradicted by Urban's observation of a normal 

 layer of collar-cells covering the yellow bodies and showing no sign of 

 degradation. 



Both authors found their cells resist caustic potash ; both found a spherical 

 wall with grauular contents (I know of no observation of a resistant cell-wall 

 in collar-cells in any stage of metamorphosis). Dendy's "yellowish colour" 

 may well be Urban's " grime Farbe " differently treated and viewed by 

 different eyes (Urban states that in other Naples Olathrinidse he has "orange- 

 gelbe, schwefelgelbe, und griiue Farben oft genug gefunden," but I never 

 saw a Clathrinid at Naples I should have described as green). 



There is strong resemblance between the descriptions and figures of these 

 cells in Clathriuids by Urban and Dendy, and the descriptions and figures 

 by Schulze (1879 b) and Polejaeff (1884) of " brown spherical algse from the 

 outer layer of a Hircinia variabilis" (187!' b. p. 38). The spheres are drawn 

 by Schulze 6 /j, in diameter and by Polejaeff 8 fj. and 9/x, described by 

 Schulze 6 fi to lOyu. They have a cell-wall and uniform granular contents, 

 and give the sponge a red-brown colour (1879 b, p. 25). The only differences 

 are : (a) some of the cells attain a diameter i /j, in excess of any observed by 

 Urban and Dendy; (b) Schulze describes the colour as " violettbrauner," 

 whereas Urban found his cells " von eio-entiimlich rotlicher Farbun»\" 



It appears, therefore, that Syncrypta spongiarum is found in all stages from 

 4 to 16 cells, and as isolated monads, in the flagellate chambers of Grantia 

 compressa at Plymouth, where the collared cells ingest it. Its 16- and 32- 

 celled stages appear in the flagellate tubes of Mediterranean Clathrinidas, 

 where they have been figured as sperm-balls, and there is some evidence that 

 these stages are formed within the mesoglcea of the Clathrinid. On the other 



