XX PROCEEDINGS. 



etc. He noted that these deposits in lakes on different sides of the 

 same watershed were characterized by the presence in more or less 

 abundance of some peculiar species. He was endeavoring to obtain 

 sections of some of these deposits so as to be able to compare the varia- 

 tion of or succession in th, species since the first deposits were laid on the 

 barren beds of the lakes carved out in the glacial period. Over a 

 hundred different species had already been observed in our fresh water 

 deposits, many of them identical with those found in similar deposits 

 in the Eastern hemisphere. Among them were found the silicious 

 epicules of several species of freshwater sponges, which appear 

 to be also more or less abundant in all our freshwater deposits. The 

 following species of diatoms have been already identified in these 

 deposits : 



Cocconeis pediculus, Ehr. C. placentula, Ehr. Gomphonema 

 acuminatnm, Ehr. G. a, var. coronatum, Ktz, G. a. var. laticeps, Ehr. 

 G. cristatum, Ralfs. G. gracile, var. naviculoides, Grun. G. abbrevia- 

 tum, Ag. G. capitatum, Ehr. G. intricatum, Ktz. G. cistula, Hemper. 

 Epithemia turgida, Ehr. E. gibba, Ehr. E. g. var. parallela, Grim. 

 E. argus, Ehr. Himantidium arcus, Ehr. H. a. var. majus, W. Sm. 

 H. a. var. tenellum, Grun. H, formica, Ehr. H. pectinale, Ktz. H. 

 p. var. ventricosum, Grun. H. p. var. minus, Ktz. H. p. var. undula- 

 tum, Ralfs. H. soleirolii, Ktz. H. bidens, W. Sm. H. b. var. diodon, 

 Ehr. H. praeruptum var. inflatum, Grun. H. polydon, Brun. H. 

 polydentulum, Brun. Amphora ovalis, Ktz. A. affinis, Ktz. Cymbella 

 gastroides, Ktz. C. cuspidata, Ktz. C. ehrenbergii, Ktz. C. lanceolata, 

 Ehr. C. delicta, A. Sch. C. cistula, Hemper. C. heterophylla, Ralfs. 

 C. tumida, Ktz. N. ambigua, Ehr. N. appendiculata, Ktz. N. affinis, 

 var. amphirhyncus, Ehr. N". rirma, Grun. N". Hitchcockii, Ehr. N. 

 legumen, Ehr. N. dicephala, Ktz. N. radiosa, Ktz. N. scutellum, 

 O'Meara. Pinnularia oblonga, Rab. P. viridis, Rob. P. v. var. 

 hemiptera, Rab. P. perigrina, Ehr. P. nobilis, Ehr. P. major, Rob. 

 P. dactylus, Ktz. P. gibba, Ehr. P. divergens, W. Sm. P. interrupta, 

 W. Sm. P. mesolepta, Ehr. P. nodosa, Ehr. Stauroneis phoeni- 

 centeron, Ehr. St. gracilis, W. Sm. St. anceps, Ehr. St. fulmen, 

 Breb. St. punctata, Ktz. St. stauropheria, Ehr. Surirella robusta, 

 Ehr. S. splendida, Ehr. S. biseriata, Breb. S. bifrons, Ktz. S. 

 turgida, W. Sm. S. linearis, var. constricta, W. Sm. S. slevicensis, 

 Grun. S. elegans, Ehr. S. tenera, Grey. S. cardinalis, Kitton. 



