136 E. GROVE AND G. STURT ON 



75, PI. 5, Fig. 4), we have, through the kindness of F. Kitton, 

 Esq., inspected a perfect frustule, from which we learn that the 

 valves differ greatly in the length and form of the processes, those 

 in the one valve being long and taper, while those in the other 

 are club-shaped and spinous. 



We give a figure of the frustule. (PI. XI, Fig. 26.) 

 T. cordiferum, n. sp., Gr. and St. — Valve with slightly convex 

 sides and rounded angles. Processes distinct, circular, hyaline. 

 Surface of valve closely punctate, excepting where a conspicuous 

 clear space, having the outline of a heart, divides the central por- 

 tion from the rest. Length of side -0025". (PI. XI, Fig. 23.) 



T. weissflogii, n. sp., Gr. and St. — This species was previously 

 described by us (" J. Q. M. C," Ser. ii, Vol. ii, p. 328) with 

 hesitation as T. ccelatum, Jan., from its resemblance to the figure 

 of that species in A. Schmidt's "Atlas" (PI. 81, Fig. 19). Kecently, 

 through the kindness of Herr C. Janisch, we have examined an 

 authentic example of his species, and have come to the conclusion, 

 in which Herr Janisch agrees, that the two forms are specifi- 

 cally distinct. We have, therefore, much pleasure in naming the 

 Oamaru form after the well-known diatomist, Herr Weissflog, of 

 Dresden, whose assistance has been of great value to us in this 

 work. Valve nearly flat, with straight sides and slightly rounded 

 angles. The apices, which are large, and project but slightly, are 

 covered with delicate points. The centre is sparsely punctate, but 

 the radiating lines increase in number till at the margin they form 

 crowded lines. Length of side to -0075". 



We figure a specimen of average size. (n. XI, Fig. 22.) 

 T. pseudo-nerpaturrij n. sp., Gr. and St. — This species was de- 

 scribed and figured previously (" J. Q. M. C," Ser. ii, Vol. ii, p. 

 329, PI. 19, Fig. 19) as T. cancel latum, Grev., but since then, 

 having inspected Greville's authentic specimens, we have ascer- 

 tained that it is a distinct species. Valve with straight sides, with 

 a flat central triradiating portion, from which rises an inclined 

 plane to each apex. 



The intersection of these planes with the flat central portion 

 presents at the margin of the valve the appearance of a short 

 nerve or vein, two of which are conspicuous on each side. Our 

 figure is a little misleading, as the " nerves " are made to 

 resemble papillaa. In the centre of the valve there is usually a 

 spine, not shown on the figure. The processes are prominent, 



