1887.] NATURAL SCIENCES OF PHILADELPHIA. 241 



Harvey's Lake, Pennsylvania, and Lake Hopatcong in Northern 

 New Jersey, in nearly the same latitude, and with a common alti- 

 tude of about 1200 feet, may be classed as mountain lakes, lying in 

 the gorges between high hills, wooded or cultivated, and with no 

 outlook in any dii-ection. Of latter years, both have been enlarged 

 and increased in dej^th by the construction of gates at their outlets. 

 By this means the water has been raised and controlled, in the 

 former, for milling purposes ; in the latter, to use it as a feeder to 

 the Morris Canal. In Lake Hopatcong the water thus "backed 

 uj:)" has found its way through cross-gorges into parallel valleys, 

 originally heavily wooded, and the denuded stems and shorter stumps, 

 standing up through the glittering water or resting in the shallows, 

 suggest a prosaic if not a classical appropriateness, in the local name 

 of one of them,-the "River Styx." 



In this locality and in the so-called "Cedar Swamp," another deep 

 bay in this nine-mile-long pond, I found my principal sport as a 

 collector.- The season (the last of October,) was perhaps rather 

 late for the species represented ; but on nearly every floating log or 

 fallen tree top, or loosened stump, could be found when they Avere 

 turned over, shining patches of white or yellowish gemmules, left in 

 groups upon the smooth surface or partly hidden in little crevices 

 of bark or root. No conspicuous sponge masses, few even of the 

 filmy layers of skeleton spicules; only these scattering and loosely 

 placed aggregations. Great numbers of them were chipped off" and 

 dried for more particular examination in the laboratory. 



This kind of collecting has been found far more productive of 

 interesting species than where one limits himself to the larger, green 

 sponges. Though not a single massive sponge had been discovered, 

 representatives were collected of three forms of S. fragilis, two of 

 H. argyrosperma, one of H. repens, besides many specimens of Tu- 

 hella pennsylvanica. 



V. baleni, (PL XI, fig. iv.) came from near Plainfield, New Jersey and from Flor- 

 ida, in both, presumably, at a low level ; and one of the most robust forms of 

 S. lacustris &Qev\ in this country, was gathered from an "Ice Lake" in the Sierra 

 Nevada Mts. at an altitude of 7000 feet. (PI. VII, fig. i.) 



If a reason be sought to account for the prevailing rule in these cases, the 

 plausible suggestion may of course be made, that the water of lakes upon dividing 

 ridges or high table-lands may be deficient in the silicious constituent that would 

 be acquired later, from violent contact with rocks in the bed of mountain streams,^ 

 etc.; but a much longer series of observations and exact chemical analysis will 

 be needed to make this observation any more than a guess. 



