518 PROFESSOR GREGORY OX 



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 

 striae, are even more decisive characters.) 



81. Amphora Proteus, n. sp., PI. XIII., figs. 81, 81 b; 81 c; 81 d\ and 81 e. 

 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 00015" to 0006' ; breadth from 00013 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, from the smallest to the largest. When 

 the outer compartment is in focus, and its striae conspicuous, the stria? of the inner 

 compartments appear in narrow lines or bars, separated by white longitudinal 

 lines or raphes; and the transverse stripe, which are finely moniliform, are, espe- 

 cially, in a certain focus, traversed by longitudinal wavy lines or stria?, produced 

 by the circumstance that the granules of contiguous transverse stride are not 

 placed exactly opposite each other. In figs. 81 and 81 b, 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 strife, which extend across the 

 whole valve. These striae are about 22 in - 001" ; but in regard to the number of 

 stria? 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 stria? 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 striae exhibit the characters 

 I have mentioned as peculiar and characteristic. 



(I must here state, however, that there are some forms which, for the present, 

 I 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, e) ; but I am 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- 



