NEW FORMS OF MARINE DIATOMACE^. 525 



of the figures, the dorsal margin is convex. Ventral margin of segments undu- 

 lated. The inner curve lines arise from the point of the beaks, run a little 

 outwards, then inwards to the nodule, placed very near the ventral margin. 

 Markings entire, coarse, subdistant. Striae about 12 in 0001". Between the la- 

 teral segments are from five to eight convergent bars, marked with the same 

 subdistant, entire striae. In one focus, not here figured, nothing is seen but bars 

 from one side to the other, which are thus eight or nine in number. 



This very pretty and interesting species occurs in the Glenshira Sand, but the 

 figure given of it in my last plate {Trans. Mic. Soc, vol. v., pi. i., fig. 35), is not, 

 at all events, the usual form. In that figure the markings are too close, and it 

 may possibly represent a different species. Indeed, I have some reason to think 

 that there are two species which resemble each other in several points. But I 

 have not yet ascertained this to be the case. I have found the form now figured, 

 which is the true A. crassa, more frequent in Lamlash Bay, where, also, I have 

 observed the detached segments, previously unknown to me, and which, as may 

 be seen, are very peculiar. It occurs also in Loch Fine, though less frequently. 



95. Amphora pusilla, n. sp. PI. XIV., figs. 95 and 95 b. Form linear, with 

 rounded ends. Length from 0-0014" to 0-0021" ; breadth 00004" to 0-0006". 

 Lateral segments very narrow, dorsal margin straight, except at the ends, nodule 

 not far from dorsal margin, inner curve line also near it ; striation conspicuous. 

 Between the lateral segments are five or six narrow bars, separated by very fine 

 sharp lines, and marked by subdistant granules or very short striae. Striae about 

 24 in 0-001", very strong at the margins of the frustule. 



This little form is not very rare in the Loch Fine dredging, so often referred to ; 

 and occurs also, though more sparingly, in Lamlash Bay. In general aspect, it 

 resembles a delicate miniature copy of the preceding species ; but the form of the 

 segments, the curve lines, and the striation, are all totally distinct. 



96. Amphora granulata, n. sp. PL XIV., figs. 96 ; 96 6; 96 c; 96 d; 9Qe; and 

 96 /. Form of frustule linear, broad, with slightly convex sides, and truncate ex- 

 tremities. Length from 0-0017" to 0-003" ; breadth 0-0008' to 0-0013". Lateral 

 segments slightly arcuate on the dorsal margin, which is suddenly narrowed at 

 the ends ; ventral margin quite straight, or slightly concave, apices sub-acute. 

 Segments marked with fine transverse striae, which are parallel, and from 24 to 

 36 in 0-001". Fig. 96 /, represents a detached segment. When the frustule is 

 so focussed that the lateral segments are distinctly seen, and their striae plainly 

 resolved, the space between appears nearly blank. But in another focus, the 

 whole frustule is seen to be made up of about twelve longitudinal bars conver- 

 gent on the ends, the backs of which are marked by subdistant granules, from 

 14 to 18 in 0-001". Hence the name. I have figured these two views of each of 

 two frustules, one short and broad ; the other longer and narrower. One figure, 

 fig. 95 e, represents a somewhat larger form, which also exhibits granulated bars, 



VOL. XXI. PART IV. 7 B 



