274 GOMPHONEMA. 



Valve rather broadly lanceolate, almost regular, length about 4 to 5 times 

 the breadth, with apices obtuse, feebly rostrate sub-capitate. Raphe surrounded 

 by a distinct hyaline zone, with a rather broad stauroneiform blank space. 

 Striae slightly radiant, 10 or 11 in 1 c.d.m. 



Fresh water. Common. 



G. ventricosum Greg. (Q.J.M.S., 1856, iv., p. 12, pi. 1, f. 40; 



H.V.H. Atl., pi. 25, f. 13*), plate 8, fig. 314 bis. 



Valve lanceolate-clavate, very inflated at the median portion, with upper 

 apex inflated obtuse ; lower apex obtuse, very narrow ; raphe surrounded by a 

 lanceolate hyaline area, enlarged at the median portion and showing in the 

 type form a single asymmetrical dot. Median striae finely punctate, n to 13 

 in 1 c.d.m. Length, 3*5 to 5*5 c.d.m. Breadth at the median portion, about 

 1 c.d.m. 



Freshwater. North of Europe: Scotland (Greg. ). Norway. Sweden. Finland (Cleve). 



var. ornata. Grun. (H.V.H. Atl., pi. 25, f. 14-15). 

 Distinguished by a semi-circle of dots arranged near the central 

 nodule. 



Habitat. Guatemala. Has been found in a fossil state in Hungary. 



G. Sarcophagus Greg. (Q.J.M.S., 1856, p. 13, pi. i, f. 42; 



H.V.H. Atl, pi. 25, f. 2* ; Type No. 216), plate 29, fig. 813. 



Grunow made this a variety of G, angusfafum. It is an extremely 

 remarkable form, recognisable by its sub-paralled sides, narrow apices and 

 very distant striae, about 8 in 1 c.d.m. Length, about 4 c.d.m. 



Fresh water. Scotland, mixed with the type form (Greg. W. Sm. !), Ireland (O'Meara). 



2. A large rounded hyaline area. 



G. olivaceum Kiitz. (Baa, p. 85, pi. 7, f. 13 and 15; h.v.h. 



Atl., pi. 25, f. 20, a and b; Type No. 221), plate 7, fig. 315. 



Valve lanceolate, feebly gomphonemoid, with apices slightly produced, 

 or a little clavate. Raphe surrounded by a distinct hyaline zone which, in the 

 middle of the valve, by the abbreviation of the median striae, forms a very 

 visible pseudo-stauros. Striae radiant, 10 in 1 c.d.m. Length, 2^5 to 3*5 c.d.m. 



Fresh water. Rather frequent, the two forms often mixed together. Belgium, England, Ireland 

 Sweden, etc. 



