Mr. C. Mcrcsdikowskj on Scllupliora. 189 



This is a small aiul very delicate form, the frustules liviiiGj 

 in long, very thin, f,'elatiiiou3 tubes, in which they are disposed 

 in several rows. Whether the tubes are ramified or not [ 

 cannot say, as I have not seen entire colonies. When out of 

 the tubes the frustules move very slowly, and, as I ascertained 

 by turning them on both sides, they move on whichever 

 valve, the dorsal or the ventral, they are lying. 



The endochrome is composed, as usual in this genus, of 

 one plate, resting by its narrow median portion (m.) on the 

 dorsal valve, with the mar«:ins extended in four narrow linear 

 prolongations (;'?••) which rest on both connecting-zones. 

 The median or valve part is thicker than the prolongations, 

 as can be seen by comparing tigs. 7 and 8, m., with figs. 8 and 

 9, pr.'f and this part is a little elevated, t. e. nearer to the 

 dorsal valve than the prolongations (figs. 7, 8). In tlie valve- 

 face (figs. 6, y) these latter appear as very narrow and 

 usually short dark lines, never reaching the ends of the 

 f rustule ; in the zonal as])ect they are seen as narrow linear 

 bands, with rounded ends and straight margins occupying 

 only a small part of the coimecting-zone, not reaching either 

 the dorsal or the ventral margin of the frustule; from the 

 latter they are always more distant than from the former. 

 I'he ventral part of the frustule is therefore entirely colourless. 

 'J'he colour of the endochrome is light yellow, witii a 

 greenish tint. Pyrenoids absent. Elajoplasts variable ; 

 usually there are two small ones applied to both margins of 

 the median part along the central line (fig. 6), frequently 

 there are four (fig. 9), sometimes none. Two very small 

 elffioplasts are also occasionally to be found at the ends of 

 the prolongations (fig. 8). The central plasma is applied 

 to the iinier surface of the median portion of the chromato- 

 phore (fig. 3, pL) as a hemispherical protuberance, containing 

 in its centre a nucleus {nc.) ; sometimes the plasma reaches 

 the ventral valve (fig. 7). 



This species is rather common in some of the lagunas near 

 San Pedro (California). It may be considered a marine 

 species, the water in these lagunas connected with the open 

 sea being quite saline. 



The species is named after a distinguished Russian 

 diatomist. Professor E. Borscjow, author of a very valuable 

 work on the Diatoms of West Russia *, unfortunately 

 interrupted by his early death. 



* E. Borf9ow, ' Die Siisswasser Bacillarieu (Diatoniacecn ) des weat- 

 lichon Russlauds ' : Kiew, 1S73. 



A7in. d' Mng. N. J list. Ser. 7. IV. ix. U 



