No. 389.] REVIEWS OF RECENT LITERATURE. 
9 439 
Pond Infusoria..— The activity of the Bohemian fresh-water 
biological station is manifested by Svec’s paper on the Infusoria of the 
Unterpoéernitzer pond. Workers in fresh-water fauna will welcome 
the very full biological and systematic treatment of an hitherto much 
neglected field of investigation. Pelagic Infusoria are represented 
by but seven species, three of which are described as new. Codonella 
lacustris alone occurs throughout the year, being found under the ice 
in the winter and reaching a maximum in the spring. The lowering 
of the temperature of the pond during the summer by an influx of 
rain water is followed by a rapid increase in the number of ‘this spe- 
cies. Littoral Infusoria abound, not only among the aquatic vegeta- 
tion and the diatoms alongshore, but also in the surface scum which 
gathers in such regions. The greater part of the sixty-nine species 
recorded in the paper occur in this region. The bottom fauna con- 
tains but few individuals belonging to but six species. In all, ten 
new species are described. CAR 
Variation in Veneride.’? — The result of work on 1000 specimens 
of a Western representative of the large Veneridæ from many locali- 
ties is another illustration of the extreme variation, not only in 
color tint but in color scale and color pattern, which may exist in an 
otherwise very well demarcated form, Sixteen varieties based on 
color are described and arranged in six groups. These varieties are 
not traced to their relations with environment, though all forms, 
except those based on the number of rays, are said to be highly local. 
The varieties would appear to be discontinuous; e.g., Mr. Stearns 
appears to indicate that the number of rays is either just about the 
typical twenty or “very many” more or “very many” less. It is 
interesting to note that the two valves vary independently of each 
other. In fact, it would seem from Mr. Stearns’s description that one 
valve might be Cytherea crassatelloides var. pauciradiata, while the 
other was C. crass. var. multiradiata, With this extreme variation 
in color goes extreme stability of form and interior coloration. The 
only variety of form noted is in degree of ventricosity and elongation, 
clearly correlated with an exposed habitat calling for deeper burrow- 
ing and consequent elongation of siphons. 
1 Švec, F. Beiträge zur Kenntniss der Infusorien Böhmens. I. Die ciliaten 
Infusorien des Unterpocernitzer Teiches, Bul. nt. Acad. d. Sci. Bohême (1897), 
2 Stearns, R. E. C. Notes on Cytherea (Tivela) crassatelloides Conrad, with 
Descriptions of Many Varieties, Proc. U. s. Nat. Museum, vol. xxi (1898), pp 
371-378, Pls. XXIII-XXV. 
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