NOTEMBEB 13, 1908] 



SCIENCE 



695 



tion of the Odonata can be compared. A new 

 map showing the mean annual temperatures of 

 these countries has been compiled on the basis 

 of previous maps and more recent records of 

 meteorological observatories, and is included 

 in the volume. Classifying these temperatures 

 into groups of 5° C. each, there are obtained 

 five (or six?) zones whose mean annual tem- 

 peratures range from 30° (or more?) C. to 

 less than 10° C. The second table in the 

 introduction, a systematic list of the species, 

 gives their distribution, inter alia, by tem- 

 perature-zones. Incidentally it may be men- 

 tioned that the zone of 25°-20° C. has yielded 

 the greatest number of species of dragonflies 

 and the greatest number of endemic species. 



As may be gathered from the foregoing, the 

 ecological relations of these insects have not 

 been fully treated in the Biologia, but many 

 data have been brought together in a separate 

 paper' dealing with the composition of this 

 Odonate fauna and its relations to tempera- 

 ture, rainfall, forest areas and other environ- 

 mental factors. Two ecological topics, how- 

 ever, are incidentally referred to in the 

 Biologia volume but not in the ecological 

 paper: Mimicry and the Proportions of the 

 Sexes. 



The examples of mimicry indicated are: 

 Paraphlebia and Palwmnema (page 133, foot- 

 note if) ; Lihellula saturata croceipennis, 

 Orthemis ferruginea, Lihellula foliata and 

 Paltothemis lineatipes (pp. 212, 292) ; Dy- 

 themis cannacrioides and Cannacria species 

 (p. 2YY) ; Rhodopygia hollandi and Erythemis 

 hcematogastra (pp. 319, 338) ; Plaiyplax san- 

 guiniventris and Erythemis peruviana (pp. 

 328, 334). In none of these cases, however, 

 is there as yet any evidence for or against the 

 protective value of these resemblances. 



Proportions of the Sexes. — 10,838 specimens 

 have been cited in this work from Mexico and 

 Central America and 2,746 of the same spe- 

 cies from other countries. Of the 10,838, 

 7,165 are males, 3,673 are females. That these 



* " The Composition and Ecological Relations of 

 the Odonate Fauna of Mexico and Central Amer- 

 ica," by Philip P. Calvert. To appear in the 

 Proc. Acad. Nat. Sci. Philadelphia for 1908. 



numbers can not be regarded as having any 

 special significance may be seen from the fol- 

 lowing comparisons: 



A. Forms with dissimilarly colored wings in 

 the two sexes, males the more conspicuous: 

 Hetcerina cruentata 265 c?, 91 ? ; H. vulnerata 



43 d", 44 5; H. macropus 239 c?, 81 S; H. infecta 

 27 c?, 27 ?. 



B. Forms with uncolored wings, bodies dis- 

 similarly colored in the two sexes : Argia ex- 

 tranea 236 d", 160 S; A. pulla 414 c?, 53?; A. 

 lacrymans 7 c?, 7 2; Ischnura ramhuri 18 c?, 

 27?; I. denticollis 140 c?, 143?; I. demorsa 



44 c?, 57?; Orthemis ferruginea 196 c?, 76?; 

 0. levis 28<?, 28?. 



C. Forms with similarly colored wings and 

 bodies : Megaloprepus cmrulatus 42 c?, 32 ? ; 

 Mecistogaster ornatus 49 c?, 73 ?. 



It is more likely that these numbers are due 

 to the accidents of collecting than that they 

 represent the proportions of nature. 



Philip P. Calvert 



Univeesitt of Pennsylvania 



SOME INVERSIONS OF TEMPERATURES IN 

 COLORADO 



As a part of some botanical work being 

 done on the hills south of Boulder, Colo., two 

 thermographs were kept running during the 

 spring of 1908. One of these was located 

 on the campus of the University of Colorado, 

 at an altitude of 5,420 feet, the other on a 

 mesa (flat-topped hiU) about three quarters 

 of a mile to the south, and at an altitude of 

 5,835 feet. The station on the mesa is about 

 one mile east of the face of Green Mountain, 

 which rises abruptly 3,000 feet. 



As is well known, a mean difference of 

 three degrees Fahrenheit usually occurs for 

 each 1,000 feet in mountain districts, the 

 higher points being the colder. Unless " in- 

 version " occurs the records of the mesa would 

 be expected to show about one or two degrees 

 colder than the university campus. The ob- 

 servations show that inversion does occur and 

 that the night temperatures on the mesa are 

 distinctly higher than on the university cam- 

 pus. For the present note it will be sufficient 

 to give certain data for the month of May. 



