34 Prof. P. T. Cleve and Mr. C. Mercsclikowsky on 



is probably T. tetraplasta, a new species, characterized by the 

 presence of four libroplasts instead of two, as is usually the case. 

 Tlie third figure is doubtless the T. vitrea, but the description 

 of the endochrome is erroneous ; there are two plates, it is true, 

 but they extend all along the connectives, being composed of 

 an upper and a lower part, uniting in the middle by a very 

 narrow band. As the same error has been committed by 

 Pfitzer, I give here a figure (p. 33) of the endochiome of this 

 species. The two elongated bodies on the right side represent 

 the two librojdasts, so characteristic for the whole genus. 



Mastogloia Smithii, Thor. (p. 92). 



Here, again, the description of Karsten can easily mislead 

 the reader, as was the casein regard to Achnanthidium brevipes. 

 When he says " Zwei Chromatophoren sind vorhanden," 

 this is certainly not correct. In a letter Professor Karsten 

 explains that he means two pairs of chromatophores united 

 by a common pyrenoid — which is correct, and agrees pretty 

 well with the figures. But the species, as Cleve points 

 out, is not M. Smithii, and cannot be the same on account of 

 the position of the plates along the connecting-zones, a position 

 very different from what Cleve and I have observed in 

 M. Snnthii. 



My recent observations on the structure of tlie genus 

 Mastogloia have shown the descriptions and figures given in 

 my ' Etudes sur FEndochrome des Diatomees ' to be very 

 exact. 



Cocconeis scutellum, Ehr. (p. 93). 



The foramina in the chromatojjliore-plate are not real. 

 The margins in this species are sometimes deeply indented 

 and the lobes may come in contact, thus ])roducing a kind of 

 pseudo-foramina. 



Amphora leta (p. 107). 



Tliis is no doubt the same species that I have described in 

 Etudes s. I'End. pi. v. fig. 9. The endoclirome is the same, 

 the outlines of the frustule are the same, and as to the divisions 

 of the zone Karsten says " Zonen mit punktirten Linien." 

 I have but little doubt that this is the A. composita Jan 

 figured in A. S, Atlas, pi. xxvi. fig. 44, which I believe to 

 be a good species. According to Cleve, A. beta might repre- 

 sent A. sulcata (Bieb. ?), Per. (Diat. mar. d. Fr. pi. xlvii. 

 fig. 7), but the outlines of the frustules in both species are a 

 little difi^crent and the size of the latter is smaller. 



