296 Mr. C. Mereschkowsky on Californian Diatoms. 
48, Trachyneis aspera, Ehr. San Pedro, common; Monterey, 
rather common. [M.] 
49. Trachyneis aspera, var. intermedia, Grun. San Pedro, 
not rare. [M.] 
Valve lanceolate, axial area rather broad on one side of the 
raphe, absent on the other. 
50. Pleurosigma estuarii, Bréb. San Pedro, rare. [C., M.] 
51. Pleurosigma cuspidatum, Cl. San Pedro, not rare. [M.] 
Endochrome composed of four narrow bands, having the 
same disposition as in P. Normanit. 
52. Pleurosigma elongatum, W. Sm. Laguna near San 
Pedro, marine and brackish, common. [M.] 
Endochrome composed of four elongate and_ straight 
bands, 
53. Pleurosigma formosum, W. Sm. Northern California, 
rather common. | M.| 
Endochrome composed of four very elongate and tortuous 
bands. 
54. Pleurosigma formosum, var. longissima, Grun. San Pedro, 
not rare. [M.] 
Length of the valve..........-- 0°465 0538 
Dread thie 5 cate cieas aes ease e 0042 0-055 
Oblique striae cs wa d¥e es vs ae oi 10-11 11-125 
Valves broader than in the type species; differs from 
var. balearica, which has the same broad valves, by the 
strie, which in the latter are 8-9 in 0:01 mm. 
55. Pleurosigma latum, Cl. Santa Monica, on Macrocystis, 
rather common. [M.] 
Endochrome composed of four bands forming several undu- 
lations of exactly the same kind as in P. Normanw and 
P. cuspidatum. 
56. Pleurosigma nubecula, W. Sm. Santa Monica, amongst 
Macrocystis ; Monterey, common. [C., M. ] 
Endochrome composed of four elongate and very tortuous 
bands. 
57. Pleurosigma rhombeum, Grun. [C.] 
58. Gyrosigma attenuatum, Kiitz. San Pedro, rare. [M.] 
59. Gyrosigma balticum, var. californica, Grun. Laguna 
near San Pedro, not rare. [C., M.] 
Endochrome composed of two perforated chromatophore- 
plates ; perforations narrow, oblique. 
