518 PROFESSOR GREGORY ON 
striation on the inner compartments, by the beaked form of the detached valves, 
and finally, by its varieties. (Its complex structure, and its three systems of 
striee, are even more decisive characters.) 
81. Amphora Proteus, n. sp., Pl. XIIL., figs. 81,810; 81¢; 81d; and 81e. 
Form very variable, obtuse lanceolate, elliptical, barrel-shaped, broad and trun- 
cate, long and narrow, &c. It has usually the rectangular space between the valves, 
but sometimes the valves are in apposition, and then resemble twin frustules of 
Cymbella. Some of these modifications are figured. The size also varies prodigiously. 
Length from 0:0015" to 0-006"; breadth from 0:0013 to 00024". The broadest ex- 
amples are generally short. Valves acute, sometimes with arcuate, at other times 
with obtuse apices. Inner curve lines and nodules strongly marked, and inner 
compartments of the valve in a different plane from the outer ones. There are two 
peculiarities which are found in all specimens, fromthe smallest to the largest. When 
the outer compartment is in focus, and its strize conspicuous, the strize of the inner 
compartments appear in narrow lines or bars, separated by white longitudinal 
lines or raphes; and the transverse strize, which are finely moniliform, are, espe- 
cially, in a certain focus, traversed by longitudinal wavy lines or strize, produced 
by the circumstance that the granules of contiguous transverse strice are not 
placed exactly opposite each other. In figs. 81 and 81 4, the same specimen, a 
long one, is shown as it is seen in two different foci, one of which brings out the 
curve lines and nodules, the other the transverse strixe, which extend across the 
whole valve. These strize are about 22 in 0-001’; but in regard to the number of 
striae there are very great variations in this species, as I have shown, in former 
papers, to occur in other species. In some of the smaller specimens the strive are 
at least twice as numerous as in some of the larger, and even in the specimens of 
equal size they differ in this respect. But in all, the strize exhibit the characters 
I have mentioned as peculiar and characteristic. 
(I must here state, however, that there are some forms which, for the present, 
J include under A. Proteus, respecting which I have great doubts whether they 
ought not to form a distinct species. These forms have many characters in com- 
mon with A. robusta, but have uniformly a much finer striation, and consequently 
a very different aspect.) 
This species is very frequent in Lamlash Bay, and also in some of the Loch 
Fine dredgings. At first I was quite at a loss with the multitude of forms agree- 
ing in striation, but when I had observed the characters above mentioned, I was 
able to trace all these forms into one another by gradual transition. Those here 
figured are some of them very different; but intermediate forms occur. One of 
the figures represents two valves in apposition, which I suspect to belong to this 
species (fig 80, ¢); but Iam not quite certain about that one. 
I may here direct attention to the fact, that such a form as that shown in fig. 
81 e, resembles closely a twin frustule of a Cymbella or Cocconema. Yet it is con- 
