NEW FORMS OF MARINE DIATOMACEZ. 493 
central nodule indefinite. Terminal nodules considerably within the margin, 
small. The two parts of the median line terminate in the middle in small rounded 
expansions, but do not meet. Strize delicate, but sharp, transverse in the middle, 
and gradually more and more curved towards the apices, where they become nearly 
vertical. They are not so close together as in some forms in which they are 
equally delicate, and there are about 54 in 0-001”. Valve thin, flat, hyaline. 
This remarkable form occurs in Professor AttMAN’s Lamlash Bay dredging, 
where, however, it is rather scarce; also in that of Mr Mixes. 
29. Cocconeis splendida, n. sp. PI. IX., fig. 29. Form, a pure broad oval. 
Length about 0-0044’; breadth about 00039’. Valve strong, and very richly 
marked with strie, which are highly inclined and curved near the apices. These 
strize are coarse, about 14 in 0-001’, and are formed of granules, which gradually 
diminish in size towards the median line. The four or five outer granules of each 
of the striz are set as closely together as possible, while the rest are separate. This 
gives the appearance of a broad marginal band. There is a small, nearly square 
blank at the centre, which is no doubt the indefinite central nodule. The two 
halves of the median line are strong, somewhat bent at the terminal ends, where 
they form elongated expansions, lying just within the dense marginal band. The 
central ends terminate in small expansions, which lie at the upper and under 
edges of the central blank. 
This beautiful form occurs in Lamlash Bay, but it is hitherto scarce. No doubt 
it will some day be found moreabundantly. It is, with the two preceding forms, 
remarkable for the size it attains, being the largest Cocconeis yet described, while 
C. major and C. pseudomarginata are but little below it in this respect, and even 
C. nitida is unusually large for this genus. 
GROUP III. 
FILAMENTOUS FoRMS. 
Of this class of forms, the number is considerable. It is worthy of remark, 
that most of them belong, so far as I am able to judge, to the genus Denticula, 
which hitherto has yielded only fresh-water species. But there are six of which 
the genus is doubtful ; partly because the F.V. alone is as yet known, which is the 
case in four of them; partly because, if not Denticule, they cannot well be re- 
_ ferred to any of the genera in Smrru’s Synopsis. One remarkable species, the 
genus of which is still uncertain, I have been compelled to remove from Himan- 
tidium, in which genus Professor SmirH had provisionally arranged it. The forms 
of this group are 14; viz.:— 
30. Denticula (?) interrupta, n. sp. 34. Denticula nana, n. sp. 
31. ... (2) capitata, n. sp. 35. ... Minor, n. sp. 
32. ... (2) ornata, n. sp. 36. ...  distans, n. sp. 
33. ... (2) levis, n. sp. 37. ...  staurophora, n. sp. 
VOL. XXI. PART Iv. 6R 
