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



teristics as tliose of Neidium, and also the longitudinal keels or ridges, liut tlie strncture differs 

 entirely from that of Nenlium and agrees witli that of Diploneis. In niy opinion this remarkable 

 form approaches nearer to Scol. latestriata than any otlier. 



Gomplioneis Cl. N. Gen. 



Valve elongated, clavate, or asymmetrical witli tlie transverse axis. Median line straiglit, 

 more or less obliqne. Terminal fissures straiglit. Axial area narrow, linear. Central area small, 

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

 Strnctnre double: slightly radiate costse, and fine puncta, forming obliqiiely decnssating lines. — 

 Zone broader in tbe upper tban in the lower end, not complex. Cell-contents nnknown. 



I have formed tbis new genns for some species formerly considered as belonging to GompHo- 

 nema, but diflFering from it both in the strncture and in the presence of the longitudinal lines. In 

 these characteristics they agree nearly with Scoliotropis, but differ in tbe straiglit median line, and 

 the asymmetrical form of the valve. 



To Gomphoneis may perhaps also belong Gomphmiema ericnse Grun. 



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

 and Central America. 





Artificial kcy. 



Central area on both sicles of the central nodnle with rows of stigmas . . Gr. elegans Grun. 



— — — — — — — one or two stigmas 2. 



Dostse about O in 0,0 1 mm (?. Mamilla Ehb. 



— — 12 — — G. herculeana Ehb. 



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

 broad rounded upper end. and to the narrower basis. L. 0, 12 to 0,15; B. 0,02 8 to 0,03 mm. 

 Median line broad 'oblique). Axial area narro^v; central area orbicular, with a circlet of stigmas. 

 Costse 10 in 0, 01 mm., radiate in the ends. Puncta 22 in 0, 01 mm. Longititdinal lines distinct, 

 median. — Gompltonema elegans Grun. V. H. Syn. Pl. XXV f. 19. 



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



2. G. 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 nai^row, linear. Central area small, rounded, 

 with one or two stigmas. Costie slightly radiate at the ends, 8 to 10 in 0, 01 mm., alternating 

 with double rows of fine puncta, forming obliquely decnssating rows, 16 to 20 in 0, 01 mm. Longi- 

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

 f. 1. Gompltonema oregonicnm var. maxima Grun. V. H. Syn. Pl. XXIII f. 3. 



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



3. G. hereuleaiium Ehb. (184.5). — V. clavate, with broad and rounded or subtruncate 

 upper ends. L. 0,o6 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, 01 mm., alternating 

 with double rows of puncta (about 22 in 0, 01 mm.) forming obliquely decu!;sating rows. Longi- 

 tudinal lines faint, sometimes obsolete, median. — Gomphonema herctil. 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 CoU.)! 



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



