THE MUSEUM. 



j85 



height from seventy-live to three hun- 

 dred and iifty feet. It then reinauied 

 inactive until the spring of i88S, when 

 eruptions again began, continuing 

 through the entire season and the suc- 

 ceeding winter. At this time the in- 

 tervals of eruption were at first every 

 hour and fifteen minutes, increasing to 

 two hours There is no way of deter- 

 mining the time of an eruption save by 

 the increased iknv. "Immediately 

 preceding an eruption a violent up- 

 heaval occurs, raising the entire vol - 

 ume of water in the crater nearly 50 

 feet, when instantly one or two, and 

 sometime'; three, terrific explosions 

 occur, followed closely by the shoot- 

 ing upwards of water, and oftentimes 

 masses of rocky formation, to a height 

 of 200 to 250 feet. Tons of rock have 

 in this way been hurled into P~irehole 

 river, some pieces fully 500 feet from 

 the crater. 



Near E.xcelsior Crater is Turquoise 

 Lake, in whose waters are seen sonie 

 of the most delicate and varied colors, 

 far more beautiful than can be imag- 

 ined by even the most imaginative. 

 A little further away is Prismatic Lake, 

 of much greater expanse, the water 

 displaying another variety of colors. 



Such sights are too much, such 

 scenes too grand, to take in for too 

 long a time. We must have time to 

 muse .over and think about them. We 

 had observed in the lakes and in the 

 outlet to the crater numerous dead 

 dragon flies. They had met a sad 

 fate and had come to an untimely 

 death by too close proximity to these 

 hot steam vents. Now these .were 

 what we were after, though we had as 

 yet taken none in the Park. There is 

 no law against catching insects or dig- 

 ging plants, so we prepared for action. 

 We soon struck a warm stream along 

 which hundreds of beautiful large red- 

 winged Libillnla satiirata were sport- 

 ing themselves, and mixed among 

 them were many smaller blue-colored 

 Mcsothcmis simplicicollis I'ar. collo- 

 cala. All the boys took a turn, and 

 that ravine was well swept. The in- 



sects were frequently seen depositing 

 eggs in water that was hot to the 

 toucfi. 



Digressing for a time from the nat- 

 ural wonders of the Park, the geysers, 

 we may devote a little space to the in- 

 sects. 



Dragon flies in the Rockies are quite 

 abundant in numbers and in species, 

 are interesting to study and have re- 

 ceived some little attention from ento- 

 mologists. Most conspicuous of all 

 the dragon flies on account of its large 

 size and brilliant red color is Libcllula 

 saturata Uhler. This beautiful speci- 

 men has in the male a beautiful red 

 body and abdomen, with wings reddish 

 brown from the triangle to or beyond 

 the nodus. The female is far less 

 common than the male, has much less 

 color on the wings and body, as usual 

 in most Odonata, and was sought for 

 eagerly, though comparatively few 

 were taken. Saliirata has been col- 

 lected from various parts of Mexico, 

 from Guatemala, Colombia (.-'), Cali- 

 fornia, Arizona, Montana and the Yel- 

 lowstone National Park. What was 

 formerly a separate species described 

 by Hagen as croccipcniiis has been de- 

 termined by Calvert to gradually 

 merge into Saturata (Proc. Cal. Acad. 

 Sci. , Ser. 2, Vol. IV, P. 517) and the 

 two species are made into one by him. 



The next most noticeable dragon fly 

 to L saturata is Mcsothcmis siiiiplici- 

 collis var. collocata Say. It was found 

 in the Park quite abundantly, general- 

 ly with L. saturata. On account of 

 their staying in close proximity to small 

 warm pools and running streams they 

 are not difficult to catch. One could 

 generally straddle the stream and 

 sweep from either side as they went 

 past, or secure a favorable position 

 near a pool, and sweep them while a 

 second party would keep them on the 

 wing. They fly low in the Park, do 

 not take long flights, and by their 

 bright blue bodies are quite conspicu- 

 ous, though not as much so as L sat- 

 urata. Quite a number were captur- 

 ed by throwing hats over them, though 



