THE PLANKTON DIATOMS OF THE BAY OF FUNDY 17 



SESSIONAL PAPER No. 39b 



Plate II. Fig. 5. Rhizosolenia. 



In its narrowly linear form and in the absence of lateral bristles the form here 

 figured resembles Rh. setigera — but the entire frustule is divided into oblique 

 segments of which the terminal ones are attenuated in opposite directions to be 

 produced into fine spinous processes. 



Plate II. Fig. 6. Rhizosolenia. 



) 

 This form is considerably broader than the last, but lacks the oblique transverse 

 lines and terminates in a more pronounced calyptra, of which the spine, as in the 

 last form described, is turned to one side. The frustule is also distinctly punctate. 



Plate II. Fig. 7. Rhizosolenia. 



The form here figured is noticeable for its wide diameter and for the fact that 

 the annuli curve from either side to a central or axial line, while the terminal setae, 

 the only ones present, are quite short and spine-like, recalling Ehrenberg's first 

 description of the genus, which is described as "attenuate and multifid, as If 

 terminating in little roots." It may be a variety of R. imbricata, Bright. 



Plate II. Fig. 8. Rhizosolenia? 



In its general aspect the form here figured is that of a Rhizosolenia, and I 

 have little doubt that it belongs to that genus. Its most marked feature is the 

 apparent contraction of the ends of the valves, suggesting the idea of puckering. 

 At their ends, in addition to a central sharp spine of considerable length, are two 

 little teeth or processes, projecting laterally. In the general form and terminal 

 spines, the species bears a close resemblance to that figured in Gran's Nordische 

 Plankton as Ditylium Brightwellii, and, as as indicated below, may have some 

 relationship with the latter. In Fig. 8b, two frustules are shown as connected and 

 with the terminal awns oblique and decussating. The endo chrome in these was 

 gathered in circular masses at the points where the fiustules approach. 



Plate II. Figs. 9-10-11. Triceratium. 



In connection with the forms last described, those represented in Figs. 9-11 

 are of very great interest. Thus the resemblance between Fig. 9 and Fig. 8 will 

 be at once apparent, so far as the general outline is concerned, but at one extremity 

 of the delicate gelatinous (?) cylinder in Fig. 9 is a triangular and at the other a 

 quadrangular enclosed form, both of which recall variant forms of the poly- 

 morphic genus Triceratium. Mr. Brightwell, in his paper illustrating this genus, 

 gives somewhat similar figures in the case of species Triceratium undulatum, the 

 valves as in this case being enclosed in a cylinder and, again as in this case, bearing 

 a prominent central spine. This gives strong confirmation to the view that 

 39b— 2 



