324 E. GROVE AND G. STURT ON 



from -0022" to -0067" ; breadth about -0017". Not rare. (PI. 

 XVIII, Figs. 4 and 5.) 



R. lanceolata, Gr. and St., n. s.p. — Valve narrow, lanceolate, 

 tapering finely to the subacute ends. Centre and ends clear, re- 

 mainder covered with somewhat irregular transverse dotted lines, 

 about 30 in -001". Central process small but distinct. Marginal 

 set*. Length, -0065" ; breadth, -0007". Very rare. (PI. XVIII 

 Fig. 6.) 



PSEUDO-RUTILARIA. Nov. SUBGENUS. 



We have formed this subgenus for the reception of the species 

 described below, which, while resembling Rutilaria in other 

 characteristics, is without the central clasping process, so impor- 

 tant a feature of that genus. Perhaps R. recens Cleve (" On some 

 New Diatoms," Stockholm, 1881, p. 19, PI. 4, Fig. 7) may be 

 placed here. 



Ps -rutilaria monile, Gr. and St., n. sp. — A very novel and 

 interesting Diatom. Valve composed of circular or nearly circular 

 cells, the central being the largest, and furnished with a few 

 scattered spines. On each side are a number of similar cells (in 

 our specimens from 8 to 11), which gradually diminish in size to 

 the end. Length about -005". The margins of the cells project 

 on each side in small cusps, each of which bears one or two seta?. 

 The surface of the valve is faintly dotted. In the frustular view 

 the valves are seen to be in connection at the centre and ends, and 

 the processes appear to grasp each other as in Hemianlus, the inter- 

 mediate space being occupied by the setae. (PI. XVIII, Figs. 7 

 and 8.) 



Note. — In all the specimens observed we have found that the 

 number of cells on the one side of the centre exceeds that on the 

 other side by one. 



Striatelle^e. 



Grammatophora oceamca, Ebr. — One fragment observed. Strias 

 50 in -001". 



Isthmus. 



Isthmia enervis, Elir. (" V. H. Synop.," PI. 96, Figs. 1, 2).— 

 Fragments not unfrequent — corresponding with the recent form. 



Biddulphi.e. 

 Biddulphia Tuomeyii, Bail (Roper, " T. M. S.," Vol. vii, PI. 1, 

 Figs. 1 and 2 ; " V. H. Synop.," PI. 98, Figs. 2, 3).— Frequent. 



