THE FRESHWATER PLANKTON OF THE SCOTTISH LOCHS. 509 
Class BACILLARIEZ. 
Order CENTRIC. 
Family RHIzOsOLENIACE. 
Genus Rhizosolenia, Khrenb., 1858; em. Peragallo, 1892. 
45. Rhizosolenia eriensis, H. L. Smith, var. morsa, var. n. (Pl. 6, fig. 23). 
Cellulz: a aspectu cincto vise apicibus ineequaliter emarginatis ad angulos duobus 
oppositos. 
Long. sine setis 77-230 »; lat. 7-21»; long. set. 21-39 mu. 
Hab.—Loch Shiel, Inverness. 
This Diatom was very abundant in the plankton of Loch Shiel, and varied greatly 
in size. It is well characterised by the excavation at two of the opposite angles of the 
girdle-view. Mr KE. Lemmermann, of Bremen, very kindly verified this determination. 
Order PENNATA, 
Family FRaGILARIACEd. 
Genus Fragilaria, Lyngb., 1819. 
46. F. Crotonensis (A. M. Edw.), Kitton, var. contorta, var. n. 
| Cellulze in fasciis brevissimis juncte, 20-40 in fascia unaquaque, fasciis multe sed 
gracillime subspiraliter contortis. 
Long. cell. 98-115 u. 
Hab.—Loch Ruar, Sutherland (J. Murray) ! 
; We have never before seen filaments twisted in the manner exhibited by this 
| yariety. Photographs of it will be found on Pl. 2, No. 5, and also on a smaller scale of 
| magnification on Pl. 1, Nos. 2 and 5. 
IV. GENERAL REMARKS ON ScoTTIsSH PHYTOPLANKTON. 
_ These remarks apply to the phytoplankton only, as, with the exception of the 
| Bhizopods and some of the Rotifers, the animal life of the plankton has not been 
noted. 
_ We have now examined the plankton of thirty-six of the lochs of Scotland, mostly 
those of the north-west of the country and of the Outer Hebrides, In our first paper * 
‘Wwe gave a detailed account of the plankton of fourteen of these lakes, and some general 
conclusions with regard to the main features of the plankton. In many of the lochs 
examined the phytoplankton is relatively abundant, and some of the most salient 
features of the plankton are to be noted among the Algz. 
| A large part of the phytoplankton—we are inclined to think considerably more 
* W. West and G.S, West, “Scottish Freshwater Plankton, No, 1,” Journ. Linn. Soc., bot., xxxv., 1903, pp. 
| 619-556, pls. 14-18. 
TRANS. ROY. SOC. EDIN., VOL, XLI. PART III. (NO, 21), 75 
