184 



SCIENCE. 



[N. S. Vol. XVIII. No. 449. 



informed that the same insect had been sent 

 in during July from British Columbia where 

 it had been found by Dr. H. G. Dyer, who was 

 collecting for the department. 



During a visit to Maine in June, a large 

 number of larvEe of Eucorethra were taken 

 from the spring where the barrel had been 

 sunk. It was noticeable that larvse of other 

 kinds of mosquitoes were absent, although the 

 adults were very numerous in the immediate 

 vicinity. During the past month many more 

 larva; have been sent me from the same source. 



I found that they were very fond of the 

 larvse of the different species of Gulex and 

 that they ate them, apparently with great 

 relish. On several occasions fourteen Euco- 

 rethra larvse ate, during the night, sixty Culex 

 larvffi out of the seventy that had been placed 

 in the water with them. When eating the 

 larvae of mosquitoes smaller than themselves, 

 the victim is caught, shaken violently a few 

 times, and swallowed in a few seconds in very 

 much the same way that a pickerel would 

 catch and swallow a smaller fish. 



As yet no exijeriments have been made to 

 see if this new species will devour the larvje 

 of Anopheles as readily as they will those of 

 Culex. Whether or not this species will thrive 

 in the climate of southern New England is 

 as yet uncertain, but experiments are now be- 

 ing carried on to determine this point. 



Wm. Lyman Underwood. 



Mass. Institute of Technology, 

 Boston. 



the ascending obelisk op the montagne 



PELEE. 



Not the least remarkable of the many ex- 

 traordinary conditions that have been asso- 

 ciated with the recent eruptions of the Mar- 

 tinique volcano is the extrusion of the giant 

 tower of rock, a veritable obelisk, which to- 

 day dominates the mountain, and which has 

 given to it an added height of 800 to 900 feet. 

 Pelee is no longer 4,200 or 4,428 feet in ele- 

 vation, but upwards of 5,000 feet. On May 

 31 last, before it lost 180 feet of its summit, 

 it reached exactly 5,200 feet. This tower of 

 rock, the nature of which was first properly 

 made known by Professor Lacroix, issues di- 



rectly, and to all intents and purposes ver- 

 tically, from the summit of the new cone of 

 the volcano (of whatever precise nature this 

 cone may be) which had been built up in the 

 ancient crateral-basin (the Etang Sec) to a 

 height of 1,600 feet or more, and virtually 

 plugs it. Where it is implanted, it has a 

 thickness of some 300 to 350 feet. From 

 certain points of view the obelisk seems to 

 maintain for most of its height (800+ feet) 

 a fairly uniform thickness; from other points 

 it shows a rapidly tapering surface, with a 

 termination in a needle summit, a true 

 aiguille. It is gently curved or arched toward 

 the southwest, or in the direction of Saint 

 Pierre, and on this face it is cavernous or 

 openly slaggy, showing where successive and 

 repeated explosions had carried away portions 

 of the substance. On the opposite side, or 

 toward the east-northeast, the surface appears 

 solid, is smoothed and even polished in part, 

 and shows longitudinal parallel grooves and 

 striae, very much like glacial markings. On 

 this side it shows plainly the marks of hard 

 attrition, the effect of rubbing upon the en- 

 casing rock — the mold, in fact, that deter- 

 mined a portion of the exit-channel. 



The constitution of this extruded ' cork ' 

 is undeniably lava — a lava whose viscosity or 

 rapid solidification did not permit it to flow 

 over, but which under the giant stress of the 

 volcano simply moved upward, solid from base 

 to summit, and receiving accretions to its 

 mass only from below. The most cursory 

 examination of the relations existing would 

 immediately point to this form of growth and 

 development, but the carefully conducted 

 angle-measurements and observations of con- 

 tour made by the representatives at two sta- 

 tions of the French Scientific Commission 

 leave no possibility of doubt in the matter, 

 and they further furnish us with data touch- 

 ing the rate of growth. Thus, in eight days 

 preceding June 7 this grovrth was, as we are 

 informed by M. Giraud, ten meters; and in 

 the four days preceding June 15 (a period 

 within the time of my recent visit to the 

 volcano) it measured six meters. The con- 

 sideration of the depth to which this giant 



