THE PLANKTON OF EASTERN NOVA SCOTIA WATERS 



SESSIONAL PAPER No. 22a 



been recorded from the North Sea, Iceland, and the neighbouring parts of the north 

 Atlantic. 



Another form was observed in August, 1902, which appears to be allied to the 

 above, and which may provisionally be referred to the same genus. One surface of the 

 central disc in this instance is vaulted, and each of the six projections is divided into 

 three tapering curved spines, the middle one of eachi group being curved inwardly 

 towards the flatter of the two surfaces of the disc. In the specimen observed the disc 

 measured 68//, the spines 40. For convenience the species may be called H. spina- 

 trifida (Plate III., fig. 6.) 



I was inclined to refer to the same group an organism which was met with once 

 in an oyster's stomach at IMalpeque (Plate III., fig. 4), and which is evidently identical 

 with Hensen's ' Sternenhaarstatoblast ' (Ic. Taf. IV., figs. 23 and 24). I notice, how- 

 ever, that Hensen describes ciliation in the interior of his cysts. 



HALOSPH^RA — Schmitz. 



This genus occurs in the form of free-swimming globular cysts, within which the 

 contents break up into swarm-spores. 



H. viridis Schmitz, first observed at the Naples Zoological Station, is a very fam- 

 iliar and abundant element of the plankton in June and July. The youngest cells have 

 diffused chlorophyll with scattered starch-grains and the nucleus is not visible. Even- 

 tually the protoplasm exhibits peripheral divisions. It is segmented mto numerous cells, 

 still connected by protoplasmic bridges (Plate III., fig. 7), which soon are broken, the 

 individual cells fashioning themselves into monadiform swarm-spores (fig. 7a). The 

 largest cells measured were 360;^. in diameter. 



SILIGOFLAGELLATA. 



' Cells without external membranes with one or two flagella, one central nucleus 

 and frequently many yellowish broM^n chromatophores, living within a shell formed of 

 solid or hollow siliceous rods. Peproduction unknown.' 



The above is the diagnosis given by Lemmermann of this singular group of which 

 I have found for the most part only empty shells belonging to the genera Distephanus 

 and Ebria. 



DISTEPHANUS — StoJir, 



D. speculum (Ehrenb.) Haeckel is met with in a variety which appears to be that 

 named regularis by Lemmermann, as the radial spines from the basal hexagon (20 fx 

 in diameter) are equal in length (15 ,a). 



EBRIA — Borgert. 



Ehria tripartita (Schum.) Lemmermann (PI. III., fig. 9) was not uncommon in 

 August. The genus differs from Distephanus in having a solid skeleton and two 

 flagella. It has hitherto been recorded from the Baltic and the Gulf of Naples. The 

 shells (which measure 20/7. in diameter) or fragments thereof, frequently occur in the 

 stomachs of oysters at Malpeque. 



FOBAMINIFEBA. 



Comparatively few forms were observed in the plankton, and some of these were 

 undoubtedly young examples of bottom forms swept up by storms. Only once in Sep- 

 tember did a thoroughly planktonic form make its appearance, viz., a young Globi- 

 gerina (sequilateralis ?) 150// in diameter with short delicate spines. 



