of Microscopical Organisms. 337 



Fig. 27. EuNOTiA . This is possibly a variety of 



Eunutia dizyga of Ehrouberg, but has only two teeth 

 approximate at the middle instead of four. The stria) are 

 fine, but distinct. 



Figs. 28, 29. These were doubtfully referred to Fragi- 

 laria constricta of Ehrenberg := F. undata, S. B. D., which 

 is represented as sometimes constricted and sometimes 

 inflated at the middle. These two are probably of the 

 same species, but F. undata is a fresh-water form. As, 

 however, it is a widely diffused species, and occurs on this 

 continent, this form may possibly be of identical species 

 with the British variety. , 



Figs. 30 and 31. Pinnularia dilata, Bail.^ nov. sp. 

 Small, linear ; in lateral view slightly dilated at centre and 

 ends ; ends obtuse and rounded ; median band large, cen- 

 tral nodule distinct. In front view panduriform ; the con- 

 strictions meeting the connecting membrane at the centre. 

 Stria; fine, close, and nearly parallel. 



Hub. Lat. 0° 29' 58" N. Long. 45° 58' 33" W. Para 

 River. 



The front view of this species resembles an Amphiprora, 

 the lateral view a small P. nobilis. It is only on turning 

 a frustule over, that its true nature is apparent. The strise 

 in both views are fine and nearly parallel. The form was 

 found at the depth of thirty-three fathoms. 



Fig. 32. Stauroptera . This form, which is 



doubtfully referred to Stauroptera cardinalis of Ehrenberg, 

 does not at all agree with Kiltzing's figure of that species, 

 nor can I regard it as identical with Stauroptera aspcra, 

 which it more nearly resembles. It is not so large and 

 stout as S. cardinalis, and the sides taper more, while it dif- 

 fers from the S. aspera in the striae being lines not resolv- 

 able into dots, and of considerable fineness. Moreover the 

 stauros is not dilated, and reaches the margin. It ap- 



JOUKNAL I!. S. N. II. 43 JULY, IStil. 



