THE PLANKTON DIATOMS OF THE BAY OF FUNDY 15 



SESSIONAL PAPER No. 39b 



Plate I, Fig. 4. Chaetoceros species ? 



This form also resembles Ch. decipiens, Cleve in the cup-like form of its frustules 

 and in the number and attachment of the lateral awns, but the terminal curved 

 awns are not clavate, and the lateral bristles, which are spinous, after slight diver- 

 gence at the base become nearly parallel. \ 



Plate I. Fig. 5. Chaetoceros. 



This specimen has the general form and structure of Ch. decipiens, Cleve, 

 but in certain of the cells (primary) are inner tiansverse partitions which project 

 in the form of two high cone-shaped processes, each of which at the apex bears 

 a conspicuous dichotomously divided spine, which is very characteristic, while 

 the other (or secondary) cells are almost flat. It is to forms like these that the 

 name of Dicladia mitra has been given, but they are now thought to be resting 

 spores of Ch. decipiens. 



Plate I. Fig. 6. Chaetoceros. 



This form is probably related to the last, but between the two cingula the 



lateral surfaces are conspicuously undulate, with a prominent median cone on 



either side, separating two equally marked depressions, while upon the ends of 



. the frustule two diverging filiform spines arise from the centre of each cingulum. 



Plate I. Fig. 7. Chaetoceros. 



This Ls probably also a series of resting spores of Ch. decipiens but the branching 

 processes are more numerous. 



Plate I. Fig. 8. Chaetoceros. 



In this case there are also numerous processes, arising from a single convex 

 enlargement or dome, but these are alternately long and short and unbranched. 



Plate I. Fig. 9. Chaetoceros chriophyllum — Cast. 



This form differs from the preceding in the fact that the quadrangular valves 

 of the frustules, instead of being flat or concave, are convex, while the setae or 

 horns, which are of great length, arise from towards the middle of the valves and 

 not from the corners, being at first turned downwards and then, somewhat abruptly, 

 curving upwards, the single awns on either side making with those of the opposite 

 side nearly a right angle, while the terminal awns are much shorter, and diverge 

 at an angle of about 38°. Except in this latter character the species bears much 

 resemblance to Chaetoceros volans of Cleve. It is probably a variety of C. 

 chriophyllum — Castracane. 



