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NEW FORMS OF MARINE DIATOMACEZ. 517 
phorz, the inner compartments seem to be in a different plane from the outer 
ones. This species exhibits two frequent varieties, both smaller than the typical 
form, which are figured (figs. 80 6, and 80c). One is long and narrow, its length 
being 0:0032", its breadth hardly 0:0008". The other is short and broad; its length 
being 0-002’, and its breadth 0:001". Both have the soft, hazy, indistinct aspect 
of the larger form, and both, when carefully examined, exhibit the same characters, 
except that the striation is perhaps somewhat finer. 
(Since the above was written, I have found that this species not only belongs 
to the complex group, but is one of the most interesting forms in that group. As 
will be seen in the descriptions of various complex Amphorw, the complex struc- 
ture is only seen in one focus, while in another, the frustule exhibits the charac- 
ters of a simple Amphora. This is peculiarly the case in A. spectabilis. The 
simple view, shown in fig. 80, is so thoroughly simple, that it never occurred to 
me that it could possibly conceal a second and more complex structure. But 
when I happened to examine, under a rather high power, and with oblique 
light, a frustule well placed for bringing out this structure, I detected the appear- 
ance shown in fig. 80d. In this case, the coarse transverse striz of the middle 
part, as seen in fig. 80, were still traceable, at the margin only, on one side, be- 
cause the frustule did not lie quite flat. In other examples, no such traces are 
visible on the complex view, although in general the very strong and elongated 
central nodules shine through. In fig. 80d, it will be seen that the whole frus- 
tule is composed of parallel, longitudinal, very slightly convergent bars, with a 
narrow sulcus between each two bars. These bars are transversely striated, and 
the strize, though much finer than even those of the inner and terminal com- 
partments of the valves, are yet quite distinctly seen, even more so than the 
others, being apparently free from the haziness above alluded to. Strice of the 
bars, in this view, about 50 in 0-001’. 
In this remarkable form we have the unusual occurrence of three distinct sys- 
tems of striation; 1s¢, The coarse, soft, and hazy transverse strize of the outer and 
middle compartments of each valve, on the simple view, fig. 80; 2d/y, On the same 
view, the finer and radiate strize of the two terminal inner compartments of each 
valve, which lie in a plane inclined to that of the middle compartments; and, 3dly, 
The still finer and parallel strize crossing the longitudinal bands, in the complex 
view, fig. 80 d, which lie again in a different plane. The frustule is also remarkable 
for its convexity, which is probably the cause, or one chief cause, of the indis- 
tinctness of the markings on the simple view.) 
This beautiful species is tolerably frequent in Professor ALLMaN’s dredging 
from Lamlash Bay, and in one from Loch Fine, less so in the other dredgings. 
The short variety is even more frequent than the typical form. The species 
has some resemblance to the preceding one in general form and coarseness of 
striation. But it is at once recognised by its hazy indistinct aspect, by the finer 
VOL, XXI. PART Iv. 6 Zz 
