KONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 26. M:o 2. 73 



teristics as those of Neidium, and also the longitudinal keels or ridges, but the structure differs 

 entirely from that of Neidium and agrees with that of Diploneis. In my opinion this remarkable 

 form approaches nearer to Scol. latestriafa than any other. 



Gomplioneis Cl. N. Gen. 



Valve elongated, clavate, or asymmetrical with the transverse axis. Median line straight, 

 more or less oblique. Terminal fissures straight. Axial area narrow, linear. Central area small, 

 rounded, with one or more stigmas. On both sides of the median line are longitudinal lines. 

 Structure double: slightly radiate costse, and fine puncta, forming obliquely decussating lines. — 

 Zone broader in the upper than in the lower end, not complex. Cell-contents unknown. 



I have formed this new genus for some species formerly considered as belonging to Gompho- 

 nema, but differing from it both in the structure and in the presence of the longitudinal lines. In 

 these characteristics they agree nearly with Scoliotropis, but differ in the straight median line, and 

 the asymmetrical form of the valve. 



To Gomphoneis may perhaps also belong Gomphonema eriense GtRUN. 



The few known species of Gomphoneis are all of fresh-water habitat and are found in North 

 and Central America. 



Artificial key. 



{Central area on both sides of the central nodule with rows of stigmas . G. elegans Grun. 

 — — — — — — — — one or two stigmas . . 2. 



/ fiostae about 9 in 0,01 mm. .... . , . . G. Mamilla Ehb. 



\ — — 12 — — . G. herculeana Ehb. 



1. G. elegans Grun. (1880). — V. sublanceolate, tapering from the gibbous middle to the 

 broad rounded upper end, and to the narrower basis. L. 0,i2 to 0,15; B. 0,028 to 0,03 mm. 

 Median line broad Toblique). Axial area narrow; central area orbicular, with a circlet of stigmas. 

 Costse 10 in 0,oi mm., radiate in the ends. Puncta 22 in 0,oi mm. Longitudinal lines distinct, 

 median. — Gomphonema elegans Grun. V. H. Syn. PI. XXV f. 19. 



Fresh water: Shasta Co. Cal. foss. (Cl. M. D. N:o 264), Pitt River, Oregon (Grove Coll.)! 



2. Gr. Mamilla Ehb. (1854). — V. lanceolate, gradually tapering to the obtuse, narrow ends. 

 L. 0,09 to 0,15; B. 0,02 to 0,03 mm. Axial area narrow, linear. Central area small, rounded, 

 with one or two stigmas. Costse slightly radiate at the ends, 8 to 10 in 0,oi mm., alternating 

 with double rows of fine puncta, forming obliquely decussating rows, 16 to 20 in 0,oi mm. Longi- 

 tudinal lines marginal. — Gomphonema Mam. Ehb. M. G. XXXVII: 2 f. 10. V. H. Syn. PL XXIII 

 f. 1. Gomphonema oregonicum var. maxima Grun. V. H. Syn. PL XXIII f. 3. 



Fresh water: Shasta Co. Calif., fossil! Pitt River, Oregon (Grove Coll.)! 



3. G. herculeanum Ehb. (1845). — V. clavate, with broad and rounded or subtruncate 

 upper ends. L. 0,06 to 0,i; B. 0,02 to 0,022 mm. Axial area very narrow; central area small, 

 rounded, with one stigma. Costee slightly radiate at the ends, about 12 in 0,oi mm., alternating 

 with double rows of puncta (about 22 in 0,oi mm.) forming obliquely decussating rows. Longi- 

 tudinal lines faint, sometimes obsolete, median. — Gomphonema hercul. Ehb. Ber. 1845 (according 

 to Chase). Grun. Casp. Sea Alg. p. 11. V. H. Syn. PL XXIII f. 2. 



Fresh water: New York! Lake Erie (Cl. M. D. N:o 40)! Winnipeg River, Manitoba 

 Grove Coll.)! 



K. Sv. Vet. Akad. Handl. Bd 26. N:o 2. 10 



