466 DE8CEIPTI0N OF [Poli/ffostrica. 



apex terminated by a mucro, knob-shaped. Length 1 -696th. Alive 

 in Niagara, and fossil at Farmington. 



GoMPHONEMA insulcire (Ehr.) — A new Holland species. 



G. tenuicolle. — Also a new Holland species. 



G. Palea. — A fossil species, discovered by Ehrenberg in earth 

 from the Jura range in France. 



G. exiguum (Kiitz.) — Minute, very smooth ; on secondary side lan- 

 ceolate; stalk rather thick, subramose. Length 1-1 440th. 



G. minutissimum (Gre\dlle.) — Very minute, quite smooth, linear- 

 cuneate, andciu-ved; on secondary side narrowly lanceolate, striated; 

 stipes slender, subramose. Length 1 -2400th to 1 -430th. Cluster 

 l-72nd. England. On Callithamnion in pools and lakes. Its presence 

 gives a yellowish appearance to the water. The terminal puncta are 

 distinct (P. 14, figs. 9 and 12.) 



G. tenellum (Kiitz.) — Small, very smooth, secondary side narrowly 

 obovate; stipes short, simple. Length l-1440th. 



G. macropus. — Lincar-cuneate, truncate at each end, quite smooth ; 

 on secondary side obovate oblong ; stipes very short or obsolete. 

 Length 1.1080th. On Yaucheria. 



G. angustum. — Cuneate-linear, truncate at each end, smooth ; 

 on secondary side obovate-lanceolate ; stipes elongated, but 

 lost in the aggregated mucous mass. Length l-720th. Wurzburg 

 and Falaise. 



G. telogrojihicum. — Minute, and very smooth, slender, cuneate, 

 more acute at the base, dilated at the apex, aggregated on a short 

 stipes branching as a simple close umbel. Length 1-1 200th. 



G. digitatum. — Very minute and smooth, linear- cuneate, flabeUi- 

 form; stipes simple, dilated. IJpward length 1 -680th. On Conferva. 



G. abhreviatum. — Frustules broadly cuneate, conjoined in a flabelli- 

 form manner, very smooth, on secondary side obovate, the apex 

 rounded; stipes rather thick. Length 1-1 152nd to l-840th. 



Var. faj hrevvpes. — Stipes very short = Echinella ahlreviata 

 (Ehr. 1838.) 



Var. (h) longipes. — Stipes elongate, subramose = G. rotundatum 

 (Ehr. 1838.) Common on fresh- water Algae. 



G. curvatuin. — Cuneate and cui-vcd, quite smooth ; secondary side, 

 obovate lanceolate (P. 16, f. 11.) 



