THE NAUTILUS. 



beaks rather broad and moderately elevated ; " a small pond, Second 

 Summit, B. C., at alt., 6000 ft." (collected by O. W. Spreadborough, 

 1905, sent by J. F. Whiteaves), about eighty specimens; somewhat 

 larger than the Walla Walla form, of light color becoming brownish 

 over the beaks in older specimens, then with irregular, alternating 

 zones of lighter and darker ; the beaks are more elevated and in 

 many specimens narrower. Although of rather different appearance, 

 the two Pisidia seem to be of the same species. '' Pond at head of 

 North Fork of Caribou Creek, East of Burton City, West Kootenay, 

 B. C." (by same); considerably smaller, but seem identical ; the 

 beaks are full and prominent, the disks rather flat towards the in- 

 ferior margin. 



This Pisidium is under doubt as to its affinities. While apparently 

 somewhat like some forms of dbditum Hald., it has also resemblance 

 with a South American Pisidium which I take for boliviense Sturany. 

 More materials from other places may help answering this question. 

 Our Pacific Slope Pisidia, and more so those of Central and South 

 America are still very insufficiently known. 



THE MANATEE SNAIL BULIMULUS DORMANT. 1 



The sooty mould of the orange, Meliola, is one of the most serious 

 results of white fly infestation of citrus groves, and is an element in 

 the injury to various plants from aphids and from some of the scale 

 insects, especially the Lecaniums, mealy-bugs, wax scales, and cot- 

 tony cushion scale. The fungus is not itself a parasite on the plant, 

 but a saprophyte, deriving its sustenance from the sweet honey dew 

 secreted by these insects. The injury to the plant results from the 

 smothering action of the fungus, the heavy coating of fungal threads 

 interfering with the healthful action of sunlight on the leaves. The 

 appearance of the various ornamental and hedge plants is also dis- 

 figured by the dark fungus. The sooty mould is especially bad fol- 

 lowing the white fly attack, owing to the large amount of honey dew 

 secreted by these insects. As the white fly larvae attach themselves 

 to the under side of the leaves, the honey dew exuded by them falls 

 to the top side of the leaves beneath, thus affording favorable oppor- 

 tunity for the growth of the fungus. So constant is the association 



1 Press Bulletin No. 59, Florida Agricultural Experiment Station. Depart- 

 ment of Entomology. 



