M 



H. H. GRAN AND K. YENDO. 



M.-N. Kl. 



fig, 19). Such spores as he has dehneated have hitherto, as far as our 

 researches extend, been found only in C. misumense (fig. 7). There are, 

 however, certain difficult points which make it doubtful whether his 

 frustules can be referred to the latter species. 



Loc. Boshu Prov. (Okamura). Misaki; Misumi; Echigo Prov. (Yendo). 

 Yeddo Bay (Cleve & Möller Diaton:î. No. 307). Enoshima; Akashi 

 (Schröder). 



Chaetoceras misumense sp. nov. 



= C. Lauderi Ralfs, var. Lauder: 1864, p. jj, PI. 8, fig. 3. 

 We found a form of Chaetoceras in the material from Misumi, which 

 accords very well with the plant which has been described and figured by 

 Lauder as a variety of C. Lauderi Ralfs. It has several peculiar char- 

 acters sharply defined, and must be mentioned as an independent species. 

 The frustules are quadrangular, measuring 20 — 30 11 in breadth, and 

 20 — 40 /< in height, and are elliptical in a valvar view. The setae spring 

 directly from the corners of the valves, at first diverging and then grad- 

 ually bending in a direction parallel to the axis of the chain. Their 



terminal half is armed with minute 

 spinous processes arranged spirally. 

 The terminal horns have a similar 

 direction to that of the setæ, but 

 bend more abruptly near the points 

 of insertion and then run almost 

 straight out, forming an acute angle 

 with one another. The two horns 

 are in one plane. They are more 

 robust than the setæ, and like them 

 are beset with minute processes. 

 The foramen is elliptical or 

 broadly lanceolate in a surface 

 view, but practically narrow lan- 

 ceolate in an optical section. There 

 are two peculiar depressions in the 

 middle of each valve, as shown by 

 Lauder. 



The girdle-bands become 

 much narrowed about the middle 

 of the complanate side of the frus- 

 tules. 



Fig. 7. Chaetoceras misumense. 



a. Terminal portion of a chan. X 360. 



h. Part of a chain seen from half 



way towards the apical side. X 360. 



c. Spores. X 360. 



a and b, from alcohol specimens; c 



from a burnt preparation. 



