!^Ir. (>. Ml resell kowsky on Californiin Dialoms. 470 



all tliCaC furni.s wliich li.ivo been coiifoiiiiilc 1 iiii k-r the name 

 of i.V. clusteriutn '- : — 



I. fJiidlf-faro not diirorin^^ from tlif \nlvo- 



I'llCO. 



A. JvMif.'-th oviT GO! mm. 



a. Fnistulc arcuate. 



aa. Hotli or one end curved back- 

 wnrds ; very large fornid, attain- 

 in}: OuG4 mm .V. tenuiiustris, var. ntrits. 



lb. Y.\nh not curved backwards. 



Frustule jrently arcuate X te?iuiroi>tn'g (tyjacii). 



J-'ru>tule str(in;^ly arcuate, semi- 

 circular X. tenui'rostrU, forma 



b. Fni.-tulo straigbt. [si-mivircuUtvU. 



Knds I'oriijinjr a hook N. tenuirustrin^ var. 



^Jtauixlifera, 

 Not forminn- a liook N. ienuirosiris, t'orma 



B. LeniTtii UOO mm. or less. [direc/a. 



Leuirtli about OOo mm .V. fniitirostn's, vnr./mrta. 



I.enjrtli about O.Jo mm A. f. var. ptirci, forma 



11. Girdle-face difleriuL'' from the valve-face. IminiUissima. 



Juistra curved on the .«ame .<ide X yranlis. 



l\o-tra curved in contrary directions . . N. yracUU, var. reversn. 



]2(». Nitzschiella californica, sp. n. (IM. IV. figs. IS-i'O.) 

 Ivedoiulo 13e;ieli, common. [M.j 



Vitlve furiitorm, abruptly terniinaling in straight rostra 

 (tig. 18). Gircllc-faee (tig.s. J 9, 20) a-symmetrieal, with one 

 side straight and the other convex ; rostra forming a knee- 

 like curve at their junction with the body, tlins being carried 

 to one side. Endochrome composed of two plate.s. General 

 length 0-()')C-<)-()(;3 mm., length of the body 0-02 5-0-029 mn)., 

 breadth O'OOSo-O-OOoo mm. 



127. Cylindrotheca gracilis (P)reb.), Grun. (PI. IV. lig. 21.) 

 !San Pedro, rather common. [M.J 



I first observed this freshwater diatom in the ^[i-ditfr- 

 rancan (Villefranehe) in purely marine wa'er, and now I have 

 met with it again in San Pedro, in marine water too and in 

 great abundance. The size is extremcdy variable, from 0"03o- 

 0-224 mm., breadth from 0-015-0 008 mm. Tho frustulo is 

 sometimes arcuate, especially in small individuals. The 

 endochrome is com])osed of 2 to 3G rounded or elliptic granul -s 

 arranged in a spiral along the inner wall.s of the IVnstule. 



128. Cymatopleura angulata, (Jrev. Calif, guano. [Gv.] 



* Small individuals of -V. biphicata have been probably also couffuuided 

 under this name. 



