NEW FORMS OF MARINE DIATOMACES. 515 
but lying nearer to the inner margin. On these lines are faint nodules, while at 
the middle of the inner margin there are distinct nodules. Length 0:0025’: 
breadth 00011’. The whole is marked by transverse strize, which also traverse 
the openings between the valves, in which openings a median line is also visible. 
Strie fine, subdistant, about 24 in 0-001". The divergent extremities are joined 
by a convex curve line. 
This very peculiar species occurs, but very sparingly, in Lamlash Bay. It has 
some analogy with A. marina, a form lately figured by Professor Smrru, in the 
Annals of Natural History (January 1857, vol. xix., pl. i., fig. 2.) But besides 
the coarser striation and distinct nodules of A. dubia, Professor Smrru describes A. 
marina as so much resembling A. afinis, that it has been confounded with that 
species on our coasts. - Now A. dubia has no resemblance whatever to A. afinis, 
nor indeed to any other known species; so that I have some doubts as to its being 
really an Amphora. The figures of A. marina given by Professor SmirH are not 
satisfactory, for they do not at all resemble A. afinis. 
77. Amphora truncata, n. sp. Pl. XIIL., fig. 77. Form of frustule slightly barrel- 
shaped, broad, with truncate ends. Length about 0-0028"; breadth about 0:0017’. 
Valves arcuate on dorsal, straight on ventral margin. Inner curve lines arise 
from the terminal margin, and bend gently inwards to a small nodule, rather 
nearer the inner than the outer margins. Inner margin of valve marked by a lon- 
gitudinal line of short transverse strize. In the rectangular space between the two 
valves, which is broad, are two similar longitudinal lines of short striz, near to, 
and parallel to those just mentioned, and between the two last-named lines or 
bars are traces of others. Valves transversely striated, but the strize are more 
conspicuous on a band at the outer margin, than elsewhere. So that the frustule 
appears, at least in a certain focus, marked with longitudinal striated bands, 
formed of short strize. 
This species is not very rare, in either of the two gatherings so often named 
in connection with Amphore. It frequently happens, that the line joining the 
ends of the valves appears to be interrupted in the middle. But by careful focus- 
sing it may be seen. 
The appearance of longitudinal striated bands on the middle part of the frus- 
tule seems to indicate a tendency in this species to the complex structure. In- 
deed, among the complex species there is one, A. guadrata, which has consider- 
able analogy with the present form. 
78. Amphora oblonga, n. sp. Pl. XIIL., figs. 78, and 78 6. Form linear elliptic, 
rather broad, the ends obtusely acuminate. Length from 0:0034’ to 0-004°: 
breadth from 0:001" to 0:0014’. The inner curve lines are strong and much 
curved, but they keep unusually near the outer margin of the valve, only in the 
middle projecting rather more than half way across. The central nodules, which 
are conspicuous, are situated outside of the curve lines, and nearer to the outer 
