92 МВ. G. S, WEST ON THE FRESHWATER ALG 
rather scarce. The apical horn was very short and only two ant-apical horns 
were present. 
From the examination of Dr. Cunnington's material collected in April, 
I agree with Schmidle's remarks upon Dr. Stuhlmann's collections which 
were made in October. The phytoplankton is essentially a Chlorophyceous 
plankton, and from the abundance of certain species of Staurastrum, it has all 
the features of a Desmid-plankton. 
Phytoplankton of Tanganyika—This lake is an elongated sheet of water 
lying between 3° and 9° S. lat. It has a length of 400 miles and a width 
varying between 10 and 45 miles. Its area is estimated at 14,000 square 
miles, and it is situated at 2700 ft. above sea-level. It is а deep lake, the 
southern end reaching a depth of 980 ft., and the northern end exceeding 
1300 ft. in several places. The mean temperature of the water is stated to 
be 24-7? C. (76:69 F.). 
Dr. Cunnington’s collections of plankton extended from July 1904 to 
February 1905, and can be considered as fairly representative of eight 
consecutive months from July to February inclusive. 
The phytoplankton is considerably richer as regards species than that of 
Lake Nyasa or Victoria Nyanza. The Chlorophycesm are not particularly 
abundant, and, as in Lake Nyasa, Desmids are practically absent. In direct 
contrast to the phytoplankton both of Nyasa and Victoria Nyanza, Pediastrum 
simplex was very scarce and the genus Colastrum was quite absent. Oocystis 
lacustris was the most abundant of the Protococcoidez, although Scenedesmus 
quadricauda was fairly general, and Scenedesmus bijugatus forma arcuatus 
was a feature of the October and November plankton. Other interesting 
species of the Protococcoidese were Crucigenia tetracantha, sp. n., Ankistro- 
desmus nitzschioides, sp. n., Cerasterias rhaphidioides, Reinsch, and Chodatella 
subsalsa, Lemm. The latter is а brackish-water species which occurred in 
abundance in one of the November collections. 
The Diatoms formed a large part of the phytoplankton throughout the 
whole eight months, and 25 of the species were not observed either in Nyasa 
or Vietoria Nyanza, Eight species of Navicula were noted, two of which, 
N. Tanganyike and N. distincta, are new. The genus Surirella was repre- 
sented by five species, of which three (S. plana, S. obtusiuscula, and 
S. Tanganyika) are new, and one of the others, S. striatula, is usually brackish 
or marine. А Diatom which I have considered to be identical with Nitzschia 
nyassensis, О. Müll, occurred in prodigious abundance from July to 
September, and in considerable quantity in the other months. The remaining 
Diatoms of importance were Synedra actinastroides, S. Acus var. ? revaliensis, 
Gyrosigma nodosum, and Cymbella grossestriata var. T. anganyikæ. 
The almost entire absence of Centric Diatoms is a noteworthy feature of 
