March 17, 1899.] 



SCIENCE. 



415 



vantage of photography in entomological illus- 

 tration, expressing the opinion that a fair photo- 

 graph reproduced by the half-tone process is in 

 many instances better than a poor drawing, 

 but that the best photographs he had seen re- 

 produced in this way were by no means equal 

 to drawings made by competent artists. Such 

 a photograph as the one exhibited, however, 

 marks a great advance on previous efforts of 

 the kind and would be invaluable at least as an 

 aid to the artist, and if transferred by photog- 

 raphy to a wood block and then handled by a 

 competent wood engraver would obviate all 

 necessity for drawing and would produce the 

 most satisfactory results which could be ob- 

 tained, since the slight failures in details could 

 be easily rectified by the engraver. 



Dr. Gill mentioned the resemblance of cer- 

 tain coleopterous larvte to certain Trilobites, 

 especially among the Staphylinidse. Ee said 

 he had been struck by this resemblance in a 

 figure of a Silpha larva, even the antennse re- 

 sembling the antennae of Trilobites as recently 

 discovered by Beecher. He mentioned the 

 figure of Fluvicola, an Isopod crustacean, in 

 De Kay's volume on the ' Crustacea of New 

 York, andLeConte'.s conclusion that it was the 

 larva of Psephenus, and asked for further in- 

 formation as to this resemblance. 



Mr. Schwarz said that this wonderful resem- 

 blance extends through several families of 

 Coleoptera. He instanced Micropeplus among 

 the Staphylinidse, a genus of Scydmseuidse fig- 

 ured by Meinert, various genera of Endomy- 

 chidte, groups of species in the old genus Silpha 

 Psephenus and Helichus among theElmidas, and 

 various genera of the Dascyllidse and Lam- 

 pyridse. The resemblance is largely caused by 

 the exfoliation of the sides of the body. What 

 its function is he did not know, some of the 

 larvae possessing it being aquatic, some sub- 

 aquatic and some terrestrial. 



The first paper of the evening, by Dr. Dyar, 

 was entitled ' On the Fluctuations of the Post- 

 spiracular Tubercle in Noctuid Larvas. ' 



The second paper included a continuation of 

 Mr. Hubbard's letters from the Southwest, pre- 

 sented with notes and comments by Mr. 

 Schwarz. The letters read at this time related 

 to the Colorado Desert and to Salton Lake and 



its insect fauna. Some discussion ensued on 

 the question as to whether the Colorado Desert 

 has been occupied at any modern period by an 

 arm of the sea, Messrs. Vaughan, Schwarz and 

 Gill taking part. 



L. O. Howard, 



Secretary. 



THE ACADEMY OP SCIENCE OF ST. LOUIS. 



At the meeting of the Academy of Science 

 of St. Louis of March 6, 1899, Professor J. H. 

 Kinealy described some experiments on lifting 

 water by meaus of compressed air, as is done 

 by the Pohle air-lift pump, and discussed the 

 eflBciency problems of the use of apparatus of 

 this description. Three persons were elected 

 to active membership. 



William Teelease, 

 Recording Secretary. 



DISCUSSION AND COBBESPONDENCE. 



THE IMPORTANCE OF ESTABLISHING SPECIFIC 

 PLACE- MODES. 



To THE Editor of Science — Sir : I use the 

 word ' place-mode ' to embody a well-known 

 idea, namely, that a species has a different 

 mode {i. e., a different prevailing condition of 

 size, color, etc.) in different localities. The 

 person who seeks to determine a place-mode 

 determines the prevailing dimension of the 

 principal measurable qualities (and practically 

 all qualities of organisms are measurable) of a 

 species as it occurs in the locality in question. 



The importance of this work is as follows : 

 It fixes the condition of a species in a particular 

 locality at a particular time ; it affords a base 

 from which we may measure any change which 

 the species has undergone in the same locality 

 after a certain number of years. That species 

 in nature do undergo changes within a man's 

 lifetime is recognized by some conchologists 

 who find that certain shells of the seashore have 

 undergone within a half century an evident 

 change of index (ratio of length to breadth). 

 A case of especial interest because of the exact 

 measurements which have been made is that of 

 the rock crab of Plymouth, England, the frontal 

 breadth of whose carapace has diminished year 

 by year at a measurable rate (1 to 2 per cent, 

 in five years), a result explained by certain 



