346 



SCIENCE. 



[N. S. Vol. XVI. No. 400. 



tures which can be represented in actual 

 measurement. A very distinct difference 

 in the note is observable and has been fre- 

 quently mentioned in previous records; a 

 fact that must be borne in mind as not only 

 meaning some difference in morphology of 

 sound-producing- organ, but in controlling 

 the selection of mates. 



Special effort was made to observe the 

 copulations and determine whether any ef- 

 forts were made at crossing between the 

 two forms. In all the specimens taken in 

 coitus and which have been reported by 

 others not a single instance of such crossing 

 has been observed. 



This has been the uniform instance of 

 previous observers who have made observa- 

 tions on this point, and is evidently very 

 uniform and shows distinct sexual selec- 

 tion; that is, we have here a very evident 

 case of isolation due to sexual selection, and 

 it would appear on this basis every oppor- 

 tunity for perpetuation of the variety. 



No evidence of 'dimorphism,' as Profess- 

 or Osborn understands the term, seems to 

 be available from any source. It is certain- 

 ly not seasonal or sexual, and if, possibly, a 

 depauperate form, we would not term it 

 dimorphic unless it can be proved that it 

 may alternate with normal forms. 



It may be said in summary that: (1) 

 There is a very constant color difference; 

 (2) measurements show very close adher- 

 ence to two entirely different averages for 

 length of body, length of wing and width 

 of wing. This is best shown in curves. (3) 

 There is a totally different note character- 

 istic of each form, which must be con- 

 sidered as representing different morphol- 

 ogy of sound-producing organs as well as 

 basis for selection of mates. (4) No cas- 

 sini forms have been found paired with nor- 

 mal forms and none have been recorded or 

 have been reported. (5) There is a dif- 

 ference in genitalia though perhaps not 

 enough to exclude the possibility of mating 



and Eiley says the differences are not con- 

 stant. 



The fact that the two forms appear si- 

 multaneously or practically so in the seven- 

 teen-year period and have so many points 

 of resemblance is certainly good evidence 

 of very close relationship, and it would 

 seem safe to say that they have sprung 

 from a common and rather recent ancestral 

 form or very likely that one is a derivation 

 of the other which still represents the an- 

 cestral form for both, and taking data now 

 available it appears more likely that cas- 

 sini is the derived form. 



The cassini form appears especially 

 prominent in the brood XXII. so widely dis- 

 tributed the present year and, in my own 

 experience, has been very rare in broods V. 

 and XIII. 



A variation possibly indicating another 

 tj'i^e is noted, though represented by only 

 two specimens. (Discussed by Messrs. 

 ]\Iarlatt, Hargitt, Hopkins, Webster and 

 Ortmann. ) 



The Animal Ecology of Cold Spring Beach, 

 with Remarks on the Theory of Adapta- 

 tion: Chaeles B. Davenport, University 

 of Chicago. (In absence of author, read 

 by title.) 



Cold Spring Beach is a sandspit near the 

 head of Cold Spring Harbor, L. I. An out- 

 er harbor of strong erosive currents and an 

 inner quiet harbor of deposition are separa- 

 ted by it. In the submerged beach is a 

 shalloAV water fauna of sessile lamelli- 

 branehs, burrowing molluscs and Avorms, 

 crawling and burrowing crustaceans and 

 molluscs, and swimming predaceous animals, 

 ehieflj" fish. The struggle here is so keen 

 that certain marine forms (Orehestia, Lit- 

 torina) have been forced to the terrestrial 

 beach. The outer lower terrestrial beach 

 is covered with microscopic debris and occa- 

 sional decaying molluscs. Collembola 

 cover its stony surface, chiefly arctic forms 



