306 DR. G. P. BIDDER ON 



colour of the spherules in the fresh state is golden-brown ; the organism is 

 therefore to be assigned to the Chrysomonadinese, of which Syncrypta appears 

 to be the genus whose colony and monad agree most in form with that 

 observed, and this genus also shows a paired spot. In the new species the 

 monads are separated by interstitial jelly as in Uroglenopsis, but the shape 

 and symmetry of the individuals are as in Syncrypta ; in Syncrypta also the 

 16-celled stage alone is figured by authors, whereas Uroglenopsis is shown 

 with 64 cells or upwards. The linear dimensions of spongiarum are one- 

 fourth those of Syncrypta volvox, and the outer coating of jelly is less ; both 

 these characters may be associated with the marine habitat. The small size 

 precludes a statement as to presence or absence of fine needles in the jelly. 

 I observed five 16-celled spheres in living collar-cells of Sycon ciliatum, and 

 an 8-eelled sphere in a flagellate chamber of Grantia compressa, all of 

 diameter 3-^yu. to 4//,; the constituent monads appeared to be uniformly 

 brown spherules or polyhedra, smaller and more separated than in the 

 stained preparations. Possibly only the chromatophores were visible. 



Neither Dendy nor I have observed at Plymouth multiplication beyond 

 16 cells, Dendy 's fig. 93 being identical with my fig. 13 a, of which I wrote : — 

 "As noticed also in other sponges there are in the chambers large masses 

 containing hundreds of transparent globules (fig. 13 a) laden with small 

 detritus. While their individual size and appearance strongly suggests 

 ejecta from the cells (cf. figs. 4 & 10), their large aggregate mass" makes 

 this supposition difficult without stronger evidence" (1895, p. 42). This 

 detritus was observed in enormously greater quantities than the comparatively 

 rare spheres of Syncrypta in sponges of the same date, and even if my 

 explanation of it as cell-fseces were incorrect, it cannot be supposed to be 

 derivative from the 4-, 8-, 16-eell stages. (Note D, p. 319.) 



I propose, therefore, that the organism be assigned to the genus Syncrypta 

 until an expert removes it, and put forward the following brief diagnosis : — 



Syncrypta spongiarum, nova. — Spheres of 4, 8, and 16 golden-brown cells, 

 and isolated monads, found in the flagellate chambers of Grantia compressa 

 at Plymouth ; external diameter of sphere 3 to 12 fi. Diameter of monad 

 ^ to 3 /u, ; it has a pair of " eyespots " and a large pyrenoid. The amount 

 of inter-cellular jelly is considerable. In the Mediterranean, 32-cell stages 

 also occur. Observed in December, January, April, and(?) July. 



Dendy's fig. 82 and fig. 85 suggest the correctness of my conjecture as to 

 the collar-cells feeding on the Syncrypta [which the observations recorded 

 above have since verified on the living sponge] * ; it is possible that Syn- 

 crypta may in some circumstances survive the process and propagate itself 

 in the tissues of the sponge. 



* [It has become evident also that the brown " spherical dotted globnle " of fig. 1, C, infra, 

 p. 318, was an ingested Syncrypta sphere.] 



