414 МВ. W. WEST AND PROF. G. S. WEST ON THE 
July to October, specimens of the latter being particularly good. The 
occurrence of these members of the Tetrasporaceæ simultaneously in about 
equal abundance does not lend support to the view suggested by one of the 
authors as a result of the examination of Australian material *, viz., that 
these two plankton-alg:e are states of one and the same organism. Rather 
does it confirm Wesenberg-Lund's observations + that the two are probably 
distinet. 
The Blue-green Alga Colosphirrium Kützingianum is one of the leading 
constituents of the plankton of Loch Lomond, dominating the whole plankton 
from August to September. It is never absent at any time of the year, 
although it is greatly reduced in the cold period when Melosira granulata 
is so abundant. An interesting discovery was the occurrence of an endophytic 
Aphanothece within the mature colonies of the Culospherium. On careful 
scrutiny this .tphanothece has been found in other lakes. (Consult p. 432.) 
The Flagellates and Peridiniez are only common in the month of September. 
5. осн KATRINE, PERTHSHIRE. 
This well-known Scottish loch is 8 miles in length by three-quarters of a 
mile in breadth, and is 364 feet above sea-level. Its greatest depth is 
495 feet. Towards the eastern end, where the collections were made, the 
surrounding mountains rise to 2398 feet. The collections were made 
monthly from August 1908 to July 1909. 
Aug. 18. 1908. Temp. of water 60° F. (=15°5° OC.) Varieties of 
Staurastrum paradoaum and Nt. cuspidatum var. таейтити were very common. 
Colosphiriun Kützingianum very abundant. Diatoms few and scarce, 
Rotifers frequent. Bosmina very abundant, 
Sept. 17th, 1908. Temp. of water 56° F. (= 13:3? (.). Very similar in 
all respects to the August plankton, but containing rather more detritus and 
fragmentary organic matter, 
Oct. 16th, 1908. Temp. of water 55° Е. (= 1271? (.). Several species of 
Staurastrum still pretty common. Celospherium much reduced in numbers. 
Merismopedia tenuissima common. — Jéhizosolenia morsa makes its appearance. 
Great Increase in amount of fine detritus. No Rotifers and very few 
Nauplii. 
Nov, Lith, 1905. Temp. of water 50° F. (= 10° C). Siaurastra still 
numerous. Very little Calosphariwn and with colonies in poor condition. 
Filaments of (Kdogonium very common and much finely divided organic 
matter. /thizosolenia morsa more numerous. No Rotifers or Entomostraca 
present. 
* G. S, West, in Journ. Linn. Soe., Bot. xxxix. (1909) pp. 75, 76. 
T С. Wesenberg-Lund, ** Studier over de Danske Söers Plankton,” Dansk. Fersky.-Diol. 
op. 5, Kjobenhavn, 1904, p. 21 (of Summary). | 
