352 Information respecting Scientific Travellers, 



This plant occurs in delicate ochraceous or ferruginous masses, 

 falling into powder on the slightest touch. The filaments are so 

 slender, and the joints so obscure, that I have been unable to de- 

 termine the form of the frustules, and have therefore taken the 

 specific character from Ehrenberg ; I am also unable to ascertain 

 whether the joints are marked by any central line. Having 

 received from Mr. Dillwyn a specimen of his Conferva ochracea, 

 which I am able confidently to refer to this species, I have re- 

 stored the original specific name. Ehrenberg is no doubt correct 

 in placing the plant in this genus, as the filaments are siliceous 

 and cylindrical. 



When submitted to a red heat it acquires a reddish tinge, 

 which circumstance, together with the colour and slender fila- 

 ments, will easily distinguish it from all the other species. 



Analysis. 



, ( Joints very obscure, the central line apparently wanting, ochracea. 



' (Joints and central line distinct 2 



{Filaments moniliform ; frustules connected in pairs 3 

 Filaments not moniliform ; frustules not connected in 



pairs 5 



o / Frustules and connecting portion closely striated glob f era. 



' \ Frustules with one to three lines, not striated 4 



{Frustules globular ,.. nummuloides. 

 Frustules longer than broad, cylindrical, with the ends 



rounded Borreri. 



f, r Junction-surfaces not striated varians. 



' \ Junction-surfaces striated 6 



6. 



( Frustules broader than long arevaria. 



\ Frustules two or three times longer than broad orickalcea. 



XLV. — Information respecting Scientific Travellers. 

 We take much pleasure in announcing that three enterprising bo- 

 tanists are now engaged in exploring the most interesting portions 

 of the far West, and that their collections of dried plants will be 

 offered to subscribers, in sets, as they come to hand. Two of these 

 collectors, Mr. Charles A. Geyer (well known as the botanist of Mr. 

 Nicollet's official north-western expedition), and Mr. Liiders, who are 

 for the present attached to SirWm. Stewart's party, have by this time 

 reached the Rocky Mountains. The particular field of Mr. Geyer's 

 operations, and the extent of his journey, were undecided at the 

 time of his departure from St. Louis. Mr. Liiders expects to spend 

 the next winter, and perhaps the ensuing summer, at a station of 

 some Roman Catholic missionaries on the upper waters of Lewis and 

 Clarke's or Great Snake River. These botanists being well ac- 

 quainted with the vegetation of the general Valley of the Mississippi 

 and of the lower Missouri, will doubtless avoid the common and 

 better known plants of this region ; and thus their collections may 

 be expected to prove unusually choice and valuable. 



