New Diatoms from Honduras. Described by A. Grunow. 173 
More common. To tlie above localities may be added 
Honduras, Caraccas, Samoa, Constantinople. 
I am not sure whether the two species are distinct ; in case 
they should prove not to be so, I wish to retain the name of 
P. Martensianus for both forms. The structure of the valves 
resembles that of Surirella gemma. In the middle of the concave 
margin a small dot like a terminal nodule may be perceived. 
[This form has been long known to diatomists by the MS. 
name of Surirella reniformis. I should be inclined to consider it 
a distorted form of Surirella. S. gemma sometimes occur with a 
deep indentation in one of the margins. — F. K.] 
Nitzsehia. 
N. Kolaizeclcii Grun. N. valvis lanceolatis, ad utriumque finem 
versus leviter attenuatus acutiusculis, carina marginali, punctis 
carinalibus 8-9 in ‘01 mm. valvis striato punctatis, granulis ita 
dispositis ut striarum directiones in angulo acuto sese serantes tres 
efficiant, striis transversis 17-18 in • 01 mm. obliquis 13-16 in 
•01 mm. Longit. '0G7-'12 mm., latit. valvae , 0075-‘01 mm. 
Tab. CXCIY., Fig. 10. 
Very rare in the Honduras gathering, more plentiful in the 
stomach contents of Salpa spinosa from the Southern ocean, kindly 
communicated by Herr Weissflog. This species is nearly related to 
N. lanceolata, but differs widely in its markings, which resemble 
those on Pleurosigma angulatum. 
Bacillaria. 
B. paradoxa var. tropica Grun. Valvis linearibus (hinc inde 
lateraliter monstrosa inflatus) apicibus paullum attenuatis, obtusis, 
punctis carinalibus 6-7 in ■ 01 mm. striis transversis 24-25 in 
•01 mm. Longit. • 10— • 16 mm., latit. valvre ’0065 mm. Tab. 
CXCIV., Fig. 11. Common in the Honduras gatherings, Bengal, 
Polynesian Islands. 
Distinguished from B. paradoxa by its finer striae, the striae of 
which are 20-21 in '01 mm., and the valves linear with obtuse 
apices or linear lanceolate. 
The genus Bacillaria is only distinguished from Nitzsehia by 
the union of the frustules into longer or shorter filaments [ ? and 
also by the remarkable movement of the frustules. — F. K.], a 
difference which becomes extremely dubious as several species 
of Nitzsehia sometimes occur in filaments. A similar difficulty 
exists in distinguishing the exact separation of other genera allied 
to Nitzsehia, all marks of distinction between them being in- 
constant. 
There are a few species of Nitzsehia allied to N. ( Eunotia ) 
