91 



NOVARA DIATOMS. 



Descriptions of New Genera and Species of Diatojns obtained by the 

 Austrian Imperial Frigate Nova?-a, during her Voyage round 

 the World. 



By Herr A. Grunow. 



(Translated by F. Kitton.) 



Part III. 



Navicula gemmata. GrerUle var. biseriata. Grun. — Stria? trans- 

 verse, 10 in. '001 composed of a double series of minute granules. 

 PI. 6, fig. 1. 



Polycystin Stone. Nankoori. 



A very interesting form, perhaps a distinct species. The strias 

 consisting of two rows of closely-pressed, somew r hat irregular 

 shaped granules. The central nodule is large, square, and as in 

 Greville's figure tridentate on both sides. 



The smooth space between the strias and the costas on each side 

 of the median line is less than in the type form, and the outline of 

 the valve more symmetrical. 



To this species perhaps belongs my N. spectabdis, in Verb 

 Wiener zool bot. Gesell, 1860, pi. 3, fig. 11, and which was changed 

 by Rabenhorst to JV. Grunowii, on account of the N. spectabilis of 

 Gregory. 



Entopyla omata. Grun.— Frustule large, valve linear, apices 

 rounded, median line not reaching the apices, costa? pervious (not 

 alternate) parallel, 10-12 in. -001, strias distinctly granular, in pairs 

 between the costae. PI. 6, fig. 2, a valve, b apex of a larger valve. 



Not uncommon on'Polycystin stone from Nankoori. 



Differs from Gephyria incurvata in the costas, which do not, as 

 in that species alternate, but cross the valve. In G. incurvata we 

 find a great number of minute puncta between the costae. 



Coscinodiscus ellipticus. Grun. — Valve elliptical or oblong, 

 puncta in central part large, subradiant or irregularly disposed, 

 decreasing as they approach the margin, where they form minute 

 radiant striae. PI. 6, fig. 4, a b. 



Very abundant. Polycystin stone, from Nankoori. 



Has a remarkable resemblance to Cestodiscus ovalis, Grev., but 

 I can in no instance find a trace of the round processes or nodule. 



Coscinodiscus oblongus. Grev. — Has radiating puncta, and the 

 puncta on the margin are only a little smaller, whereas our species 

 has a marginal band of very delicate and closely arranged puncta. 



Amphipleura Frauenfeldii. Grvn.— Central nodules x 1500 

 diameters. PI. G, fig. 3. 



Pleurosigma validum. Shadbolt. — Mic. Jour., vol. ii., pi. 1. 

 fig. 8. 



