BY G. I. PLAYFAIR. 123 



in Suri. margayitacea Miiller, Nyassaland, i., P1.2, f. 12, we have 

 a form of that genus with punctate costae (probably temporarily 

 only, however). The frustules of these TryhlionellcB are very 

 narrow and compressed in girdle-view, and slightly twisted round 

 their long axis. I am inclined to believe them degraded forms 

 of Cymatopleura solea, which is found in the upper reaches of 

 the river at Kyogle. In this connection, cf. Miiller, Bac. aus 

 Nyassaland, i , p. 23, f.4. 



Genus Melosira Ag. 



Melosira varians var. moniliformis (O.F.M.). (PI. v., f.l6, 17). 



Diam. 16-26; alt. cell. 16-26 (rare usque ad 60 /x). 



Lismore (3, 5, 22). Cum forma typica. 



Cf. Kiitzing, Bac, p. 53, T 3., f.ii., 1-3, whose figures work out 

 at diam. 12-20 /x. i/. varians (diam. 14-30/x) is common in the 

 river, being found in almost every gathering. [M. granulata, 

 very rare, only once noted). In var. moniliformis, the cells 

 become first semi detached and later entirely free, in which con- 

 dition they are liable to be mistaken for Gyclotella frustules. 



Genus Gyclotella Kiitz. 



Cyclotella Meneghiniana Kiitz., forma. (PI. v., f.l8). 



Diam. 12-28; crass. 11-14 /x. Striae in ambitu circ. 30. 



In the type, the central area of the valve is not sharply out- 

 lined, the striae are delicate, and the edge shows as a well-defined 

 rim 1-1^ /x in thickness. The girdle-view is rectangular, the face 

 of the valve, with the exception of the inflated half of the central 

 undulation (when present), being beneath the level of the edge. 

 These specimens were not quite typical, since they were not quite 

 rectangular in girdle-view, but somewhat inflated, the striae 

 showing over the edge. 



Yar. convex A mihi. (PI. v., f.l9, 20). 



V^alvae area centrali distincte definita, glabra, area marginali 

 rugosa vel striata. A latere cingulato visae, lateribus convexis in 

 medio planis vel plus minus undulatis. 



Diam. 8-36, diam. areae centralis 8-15; crass. 8-20 /x. In 

 ambitu striae 24-30 vel, apud cell, validiores, rugae 50-60. 



