396 Transactions of the Society. 



N. Grundleri is N. grandis (Kitton), whose valves are • 22-33 mm. 

 long, and • 04 mm. broad, with 3-4 carinal costae and 8 monili- 

 form striae in 0"01 mm. 



Sectio Perrya Kitton.* 



N. Fehigeri, Grim., n. sp. — Valve narrow linear, with oblique 

 truncate ends, and very sharp keel which is inflated on both ends 

 (as in N. scutulata, and others). Carinal striae short, 4-6 in 

 U • 01 mm. ; a second longitudinal band of similar striae (3-4 in 

 • 01 mm.) runs along the middle of the valve, to which is added 

 a third towards the ends. Transverse moniliform striae delicate, 

 20-21 in 0*01 mm. Florida (communicated by M. Febiger). PI. 



XIII. Fig. 15, ^^. 



Sectio Epithemoides. 



N. Janischii Grun. I. c. — Long, valves linear, thickened 

 towards the cuneate ends. Transverse moniliform striae fine, 22^ 

 in 0*01 mm., interrupted by stouter transverse striae, which are 

 prolongations of the carinal puncta (2^-4 in 0"01 mm.). The 

 puncta of the transverse stria3 form also oblique lines like those 

 on Pleurosigma angulatum. Pseudo-central nodule obvious. 

 Length, U • 245 mm. ; breadth of valve in the middle, • 0095 mm., 

 near the ends, 0'012 mm. Sandwich Islands, very rare. 

 PI. XIII. Fig. 14, ^. Only one half of the valve is represented, 

 the entire valve being too long for the size of the plate. 



Sectio Arcuate. 



N. Senegalensis Grun. — Valves slightly arcuate, with cuneate 

 blunt apices and convex dorsum, which is now and then obsoletely 

 constricted in the middle. Carinal puncta (or short striae) on the 

 convex side of the valve, 8-9 in 0*01 mm. ; transverse striae moni- 

 hform, 20-21 in 0-01 mm. Length • 099-0 • 138 ; breadth of 

 valve, 0' 01 1-0 '013 mm. Side view linear, slightly attenuated 

 towards the truncate ends, straight, or more or less arcuate. 

 Senegal Kiver on Nitella {leg. Perrotet). PI. XIII. Fig. 12, al c, 



900 

 1 • 



[This form, judging from the author's figures, appears to me to 

 belong to the section (or genus) Perrya, a being a partial s. v. and 

 6, c, frustular views. — F. K.] 



* I cannot agree with my friend Herr Giunow in considering the genus Perrya 

 as belonging to the Nitzschia, the structure of the valve being very different. 

 A transverse section somewiiat resembles a very narrow U with a long keel at the 

 base. The s.v. is very narrow and has a row of large dots along its entire length ; 

 this view can only be obtained by manipulating the valve in balsam ; without this 

 we only obtain a frustular aspect. — F. K. 



