Mr. C. Meresclikovvskj on Scllapliora. 191 



great ro.scnil)laiice of both species in every respect except 

 ill the tenuiiial nodules, which in S. (?) bacilli form is are not 

 transversely expanded. There can be hardly any doubt that 

 this species also belongs to the genus Selluphora and that 

 its endociirome will prove to be of the same kind as in other 

 species of this genus. 



It seems very probable that many other species of Navicula 

 belonging to Clove's gioup Mesoleiaj (and perhaps B icilbires 

 also, established by Cleve*), and especially the so-called 

 Dickicia, will also iiave to be placed in this genus. In my 

 paper "Etudes sur rEndochrome des Diatomues " I have 

 described one representative of this group (p. 17, pi. iii. 

 fig. 2'2)'\^ which is characterized by very short chromatophores 

 such as do not usually occur in the genus Navicula, while in 

 the genus Sdhrphora .short chromatophores are not uncommon 

 (figs. 9, 10, 13). It is true that the median valve part of the 

 plate is missing in my figure, but 1 may possibly have over- 

 looked it, as at the beginning of my studies on diatoms, when 

 these observations were made, I did not pay much attention 

 to tiie endochrome. 



Tiie following brief synopsis of the forms belonging to the 

 genus Stllaphora will facilitate their distinction and serve as 

 a convenient key for their determination : — 



Slriae distant in the middle of the valve (12- 



lo in 001 mm.) : freshwater forms. 



Terminal nodule.s with transverse e.x- 



);ansious. Two l;broplasts ; lateral 



prolongations of the chromatophore 



very elongated 'S'. jnipula (Kiitz.), Mer. 



Valve linear, with broad subrostrale 



ends '^- rectangularis, Greg. 



Valve linear, with rounded ends .... v. bad liar ioides (Grun.). 



Terminal nodules without e.xjuaiisions . . -S'. (?) bacillifonnis (Grun.), 

 Stria3 fine everywhere ; no libropla^ls : [Mer. 



marine forms. 

 Valve narrow, linear; fmstules enclosed 



in gelatinous tubes 'S'. Bor$<;(ncii, Mer. 



Valve elliptical ; frustules free H. elliptica, Mer. 



* Cleve, Svn. Xavin. Diat. part i. pp. 127 it 130. 



t It is erroneously named in my paper Amphipleura pellucida. Having 

 it now in a slide, I can easily see" that it is not an AviphipUura, but a 

 Dickicia ; and as the form of the valve is very ditierent from D. nlvacea, 

 the onlv species which Cleve has admitted in his sjTiopsis. it represents 

 probably a new species which might be called XaiMila {iJkkieia) 

 ohlita, -Mer. The two libroplasts of this species re.-emble those of >'^ella- 

 phoru pupu'd. 



14* 



