295 



a decidedly freshwater coUection, and Staur. dilat. W. Sm. is also 

 mentioned as a freshwater form in W. Sm., Syn. I, p. 60. 



ad Frag. æqv., pp. 187 — 189. 



Heiberg, in his Gonsp. crit. Diat. Danic, p. 61, has described, 

 under the name of Fragilaria æqvalis, a new species which he 

 has figured in PI. IV, fig. XII, and with regard to which he remarks 

 that it "Appears to be commoniy distributed." It has 20 "faint"^ 

 striæ in 10^«. De Toni (Syll., p. 682) has placed this species under 

 Frag. virescens. In the explanation of PI. XLV, fig. 39, in V. H., 

 Syn., the Frag. islandica Grun. figured in that plate (Fig. 37) is 

 mentioned as foUows: — "Cette forme marine, apparentée au Fr. 

 stridula? serait d'apres W. Arnott le Frag. æqvalis Heiberg;" in 

 VAN Hedrck's Types du Synopsis des Diatomées de Belgique No. 313. 

 a Fr. capucina var. æqvalis Grun. is present, which Grunow names 

 — but with a query — as a synonym of Frag. æqvalis Heib. 

 in my example of type no. 313 only pieces of filaments of the 

 Fragilaria in question are present, and thus verification is impos- 

 sible). Lastly A. Cleve (Beitr. z. Flora d. Båren-Insel, p. 18) thinks 

 that Frag. æqvalis Heiberg is perhaps synonymous with Frag. ca- 

 pucina. By the courtesy of the authorities of the Botanic Garden 

 IN Copenhagen I have been able to examine two coUections which 

 Heiberg (1. c.) mentions as containing Frag. æqv., one from Funen : 

 Østergaard (Lyngbye, Nord. Algeh., no. 18) and the other from 

 Jutland: near Vejle (Lyngbye, Nord. Algeh. no. 12). The former 

 sample, of which only an exceedingly small quantity was to hånd, 

 contained in addition to a quantity of Diatoma vulgare only a very 

 few indeterminable pieces of filaments of a Fragilaria. The latter 

 sample contained in addition to other Diatoms among which were 

 many specimens of Melosira varians, several Fragilaria, which 

 however, as far as I could see, were related to the group of forms 

 belonging to Frag. construens, all with more or less irregular con- 

 tours (among others Frag. constr. semibinodis was found) so that 

 none of them could have been the original of any of Heiberg's 

 figures. 



The examination of these two samples, consequently, gave only 

 negative results. 



If I express any opinion as to what Frag. æqval. Heib. is, it 



'svage 



