Diatoms from Chincha Guano. 483 



7. Grammatophora angulosa, Ehr. Very rare. 



There exist at least two different forms similar in their 

 general aspect, but differing in the strise, which are usually 

 confounded. In one of them the stria} are distinctly seen 

 under a moderately high magnify ing-power (12-14 strise in 

 O'Ol mm.), while in the other they are invisible under such 

 conditions (about 20 stria? in O'Ol mm.). The Chincha form 

 belongs to the latter, which I consider to be the genuine 

 G. angulosa, the other belonging to a quite different species. 



8. Grammatophora maxima, Grun. Rare. 



This species has been found hitherto, so far as I know, 

 only in a fossil state in Californian deposits (Redondo, Santa 

 Monica, San Pedro, Monterey, &c). I have seen several 

 beautiful specimens in the Chincha guano, and it is also 

 sometimes to be found in a living state in California. 



9. Sceptroneis caduceus, Ehr. Rare, and always in a broken 



condition. 

 Attains a large size, over 0*1 mm. 



10. Chaetoceros bicoronata, sp. n. Very rare. 



Of this species I have seen only a single endocyst, which 

 in its general outlines, as well as in the disposition of the 

 awns, resembles greatly the endocysts of C. seiracanthus, 

 Gran, recently described by H. Gran *. It differs essen- 

 tially from the latter in having a corona of spines not only on 

 one of the margins of the median part of the endocyst, but on 

 both ; the spines are also much stronger than represented in 

 the figures of Gran. Unfortunately I neglected to make a 

 drawing of this species at the time 1 found it, and afterwards 

 I did not meet with it again. 



11. Chaetoceros borealis, Bail. Rare. 



12. Chaetoceros chinchae, sp. n. (PI. XVI. figs. 3-7.) Not 

 very rare. 



Of this species I know only the endocysts, which have a 

 very peculiar appearance. Their form is elongated elliptical, 

 with rounded ends ; the margins are provided with short, 

 more or less irregular spines, which become shorter towards 



* H. Gran, in ' Norske Nordhavs-Expedition/ plate iii. figs. 40, 41. 



