February 15, 1895.] 



SCIENCE. 



191 



The title of Dr. Webster's memoir was 

 ' An Experimental Determination of the 

 Period of Electric Oscillations.' 



He is to be congratulated upon so signal 

 a success, and it is especially gi'^tifying that 

 an American should have come out in the 

 lead in competition with the two distin- 

 guished Englislimcn who contested with 

 him, and especially so as their work and 

 his were upon the same subject. 



ENTOMOLOGY. 



Dr. McCook is to be warmly congratu- 

 lated on the successful issue of the third and 

 final volume of his ' American Spiders and 

 their Spinning Work,' which has appeared 

 four years after the second volume. The 

 author is more at home in his delineation of 

 the outdoor world than in systematic work, 

 with which this volume is mainly concerned, 

 yet he has applied himself to this task with 

 commendable zeal and success and describes 

 123 species and 30 genera. Apparently (as 

 the table of contents curiously shows) he 

 had intended to carry his work beyond the 

 'orb weavers,' but his courage or his time 

 gave out as he saw his work grow to por- 

 tentous dimensions. We have to thank 

 him for thirty large and careful plates of 

 spiders coloi-ed. besides a mass of structural 

 details; they will greatly facilitate future 

 study. The price of the complete work is 

 now justly advanced to SoO. Unhappily 

 the title page is marked 1893, though the 

 preface is dated in July, 1894, and the vol- 

 ume was not issued until December, ISiM. 



Mr. a\d Mrs. Pkckham have given us 

 (Trans. Wise. Acad., X) a new series of 

 their admirable experiments with spiders in 

 a paper on their visual powers and color 

 sense ; they " prove conclusively that Atti- 

 dae see their prey (which consists of small 

 insects) when it is motionless, up to a dis- 

 tance of live inches : that they see insects in 

 motion at much greater distances ; and that 

 they see each other distinctly up to at least 



twelve inches" ; they are guided by sight 

 rather than by smell. The experimenters 

 are further " of the opinion that all the ex- 

 periments taken together strongly indicate 

 that spiders have the powei- of distinguish- 

 ing colors." 



Certainly the University of Califor- 

 nia Entomological Society has done a 

 uniqiie thing in issuing from Berkeley, Cal., 

 as a Californian journal of entomology 

 ' The Entomologists^ Daily Post Card ' at 

 $2.00 a year. A card of regulation size 

 and color is ijrinted on both sides in clear 

 type, leaving a meagi-e space for an ad- 

 dress. The number before us contains an 

 editorial on note taking, part of a list of 

 species in Edwards's last catalogue of but- 

 terflies, and a portion of a tabular key to 

 the genera of Nymphalidse. It is a curious 

 venture. 



In a recent paper on the Siphonaptera 

 (Proc. Bost. Soc. Nat. Hist., XXVI., 312- 

 3.55) Dr. A. S. Packard gives an excellent 

 resume of published observations on the 

 embryology, postembryonic historj' and an- 

 atomy and the adult structure of the fleas, 

 adding new data from his own preparations 

 and numerous figures. He is led to regard 

 them as forming a distinct order standing 

 nearer the Diptera than any other, but with 

 many points of relati(mship to the Coleoj)- 

 tera. 



Hansen gives in English (Ent. tidskr." 

 XV., 65-89, pi. 2-3) an important paper on 

 the structure and habits of Ileniimerus, a 

 Platypsylla-like insect infesting rats in 

 Africa, and which had previouslj' been 

 studied only from dried material. Sau.ssure 

 in particular had published a long memoir 

 upon it, founding upon it a new order 

 Diploglossata from its possessing, as he 

 thought, a second labium. Hansen shows 

 that this does not exist (it is diflicult to 

 understand how the ligures of Hansen and 

 Ssiussure can have bi'eu taken from the same 



