434 



SCIENCE. 



[Vol. V., No. 121. 



welcome shelter is extending over the remain- 

 ing sand-hills toward the ocean. The pine is 

 preceded, first by the sand reed-grass (Am- 

 mophila) , then hy the wild lupines, especially 

 by the two shrubby species of the place, — 

 the yellow-flowered Lupinus arboreus, and the 

 silvery-leaved and blue-flowered L. Chamis- 

 sonis, — which in spring-time are as orna- 

 mental as they are useful. 



These grounds were most wisely as well as 

 beautifully laid out, the favorable natural con- 

 figuration of the ground preserved and accen- 

 tuated, the ample driveways led along easy 

 curves around tree-plantations so placed as to 

 afford very needful shelter from the sea-wind 

 which gives an inclement character to a San 

 Francisco summer. I was sorry to see, that, 

 under a new administration of this park, these 

 good points were not appreciated as the}' had 

 been, perhaps because they are not appre- 

 hended. For changes by no means the better 

 were in progress : the avenues were being 

 widened and straightened to a certain extent, 

 and shelter cut away, seeminglj T with the ob- 

 ject of letting in the harsh west wind, or of 

 facilitating fast driving. Neither of these 

 results could be really desirable. 



Although these two handsome trees, the 

 Monterey pine and the Monterey cj-press, are 

 wholly unadaptable to the Atlantic United 

 States, as ma} T be said of almost every Cali- 

 fornian conifer, it is pleasant to know that 

 they grow fairly well in the warmer parts of 

 England, where they are highly prized. Still 

 the main hope of their perpetuity has respect 

 to their native soil. 



There is still another coniferous tree on the 

 Californian coast of equally limited range and 

 precarious destiny ; namely, Pinus Torreyana 

 of Parry. According to Dr. Parry {West- 

 American scientist, i. 37) , this tree " is confined 

 to a coast-line of not more than four miles, 

 and extending scarcely a mile inland," just 

 below San Diego. Dr. Parry makes the timely 

 suggestion that this precious bit of ground 

 should be preserved by the town of San Diego, 

 within the corporate limits of which it lies. 



A. Gray. 



LETTERS TO THE EDITOR. 

 A novel snow-slide. 



On April 22 and 23 occurred the heaviest snow-fall 

 known at this place. There was but little wind. The 

 temperature was so mild that the flakes were slightly 

 moist as they fell, and hence adhered firmly together. 

 The snow was quite porous at first, but rapidly settled, 

 and became somewhat compact. On tinned roofs and 

 on steep shingled roofs, snow-slides of the common 

 sort were frequent; but, on shingled roofs of moder- 

 ate slope, I noticed that the snow was slowly moving 

 downwards somewhat like a glacier. The thickness 

 of the snow after settling was about ten inches ; and 

 its rate of motion downward varied from one inch 

 to two feet per hour, according to situation. At the 

 eaves it bent downward like a plastic mass, and hung 

 in broad sheets in the air until breaking by its own 

 weight. I have often seen the same thing, but never 

 on so large a scale. In one case, on the noith side of 

 a building, the snow-sheet retained the curve which 

 it took as it passed the edge of the roof. It thus bent 

 inward so as to nearly touch the building four feet 

 below the cornice. Measured along the curve, the 

 suspended portion was about five and a half feet 

 long, which certainly shows considerable tenacity of 

 the snow-sheet, considering that it had fallen within 

 thirty-six hours, and that the temperature was such 

 that there was a constant drip of water from the edge 

 of the snow. It should be noted, that, at the last, the 

 whole mass — both the suspended portion and that 

 on the roof — went down in a body, with no breaks 

 anywhere. G. H. Stone. 



Colorado Springs, April 25. 



A parasitic leech. 



In the summer of 1877, at Fort Bridger, Wyoming, 

 while partaking of the hospitality of my friend Dr. 

 J. Van A. Carter, a Shoshone Indian Drought to the 

 house a fish to be served for the table. It was caught 

 in the neighboring stream, Black's Fork of Green 

 River, and was known in the locality as the 'Hela' 

 (Gila?), or whitefish. I made it out to be the so- 

 called Colorado pike, Ptychochilus lucius. It was 

 upwards of two feet in length. My attention was 

 directed to it by Dr. Carter, who informed me that 

 the fish was liable to be infested with leeches in the 

 mouth. On examining the specimen, I detected a 

 dozen leeches suspended to the sides of the tongue 

 by their terminal sucker. On disturbance, they be- 

 came very lively, clinging tightly to their position, 

 alternately elongating and shortening, and projecting 

 and retracting, the head extremity in the usual man- 

 ner of their allies. They appeared of a translucent 

 blackish hue, with eight longitudinal, equidistant, 

 raw-sienna colored stripes. In the contracted state 

 they were from an inch to an inch and a quarter long 

 by less than half an inch broad, elliptical, and with 

 the head extremity rather abruptly narrowed and 

 more or less prolonged. Elongated, they were up to 

 two and a half inches by about one-third of an inch 

 at the broadest part, and, as represented in the accom- 

 panying figure, which is of the natural size, were 

 variably cylindro-clavate, thickest behind, and taper- 

 ing forward, and more or less constricted at differ- 

 ent points. The caudal sucker, by which the leech 

 tightly adhered to its position, was of the usual 

 circular form and proportions. After removing the 

 tongue of the fish, and laying it in a dish of water, 

 in the course of an hour the leeches voluntarily 

 detached themselves, and moved about, or clung to 

 the bottom of the dish. The integument is smooth, 



