506 Mr. C. Meresclikowsky on Caltfornian Diatoms. 



middle, with rounded ends; length 0*0'i-0"140 mm., breadth 

 0*022-0'028 mm. Structure composed of cost*, which, 

 however, are very indistinct, almost invisible with an ordinary 

 magnify ing-power, the intercostal alveoli forming parallel 

 stria? becoming radiate near the ends, which are smooth. 

 Pseudoraphe very narrow, sometimes indistinct. Number of 

 stria? 5"5-6*5 in O'Ol mm. Number of puncta 8 in 0*01 mm. 

 Girdle-face as in B. arcuatum^ but with finer transverse costse, 

 usually 8 (from 6 to 10) in O'Ol mm. 



Fig. 21 shows a valve as it appears under an ordinary 

 magnifying-power, the costa not being seen and the rows of 

 puncta resembling those of Achnanthidiam brevipes; fig. 22 

 is a part of the valve under a greater maguifying-power. 



This species, which has probably already been described *, 

 but which for lack of necessary books I am unable to deter- 

 mine, is very frequent in the Aleutian Islands, and I possess 

 it also in a slide labelled " California," without further indi- 

 cation of locality. Other species which this slide contains 

 indicate tliat it comes from Northern California. 



137. Entopyla incurvata (Am.), Grun. Not rare in Southern 

 Calitoruia (Catalina ; Cleuiente Islands and the coast, 

 Jrlaliotus washings) ; Californian guano. [M.] 



Length 0*12 1-0-217 mm. ; girdle-face of a large specimen 

 O'Ol mm. ; distance between two costse 0'007 mm. 



138. Gephyria media, Arn. Redondo Beach, not rare ; Mon- 

 terey, rare. [M.J 



Length 0196 mm., breadth of the girdle-face attaining 

 0*057 mm. ; strias 5 in 0"01 mm. Eudochrome granular, 

 composed of 30-40 large granules. 



139. Grammatophora angulosa, Ehr. San Pedro, very rare. 

 [M.] 



140. Grammatophora angulosa, var. hamulifera, Kiitz. San 



Pedro, Monterey, very rare. [M.j 



141. Grammatophora arctica, 01. Not rare in Monterey and 

 in'^Morthern California, rare in Southern {Huliotus 

 washings). [M.] 



Valve linear, very slightly attenuated towards the apices, 

 breadth 0*007 mm.; stria? distinct, 12 in 001 mm., com- 

 posed of distinct puncta; length of the frustule 0*028- 

 0054 mm., breadth 0"013-0*021 mm.; septa forming two or 



* If not, its proper name would be R. gibbosum. 



