514 Mr. C. Mereschkowsky on Californian Diatoms. 
have observed * I have never seen such narrow elongated 
valves as represented in fig. 23. It seems therefore advisable 
to distinguish it as a separate variety. The puncta of the 
valve are also much larger, and there is a punctum to be seen 
at the bifurcation of the awns which does not exist in the 
type species. General length 0°031 mm., length of the body 
0°018 mm., breadth 0°007 mm. 
186. Chatoceros lyra, Mer. Northern California, very rare. 
[M.] 
See my paper ‘f On Polynesian Diatoms,” chapter iv. 
187. Rhizosolenia setigera, Brightw. San Pedro, rare. [M.] 
Bristles very long, straight or arcuate, with a small bright 
punctum at the summit of the calyptra, or without it. Length 
of the frustule (without the bristles) 0°l mm. 
188. Rhizosolenia Stolterfothii, Per. San Pedro, rare. [M.] 
189. Rhizosolenia styliformis, Brightw. San Pedro, rare. 
[M.] 
190. Skeletonema costatum (Grev.), Cl. San Pedro, not 
rare. [M.] 
191, Stephanopyxis ferox, Grev. San Pedro, rare; Calif. 
guano. ([Gv., M.] 
192. Stephanopyxis turgida, Grev. Calif. guano. [Gv.] 
193. Anaulus birostratus, Grun. [V. H.] 
194. Biddulphia (Triceratium) alternans, var. tenuipunctata, 
Mer. Northern California, very rare. [M.] 
See my paper “ On Polynesian Diatoms,” chapter iv. 
195. Biddulphia (Triceratium) antediluviana (Ihr.), V. H. 
San Pedro, very rare. [M.] 
| have seen only one specimen, which was almost identical 
with the figure of Brightwell representing Ampjitetras tessel- 
lata +, and could therefore be determined as well as B. tesse/- 
lata. I fail, however, to see any difference between this latter 
species and B. antediluviana, except in the alveoli of the first 
species being less coarse (which is also the case in the specimen 
from San Pedro) and the marginsof the valve less concave than 
in the second one, although in this regard B. antediluviana 
* 1 have given a figure of Ch. tmewrvus in my paper “ Note on 
Diatoms from Chincha Guano,” in Ann, & Mag. Nat. Hist., November 
1900. 
+ ‘Diatomeentafeln zusammengestellt fiir einige Freunde,’ pl. ili. 
fig. 11. 
