114 THE AMERICAN MONTHLY [May, 



the species of the United States. These facts are corroborated by nu- 

 merous observations in a state of nature. I have never found them mat- 

 ing except in. early spring; March and April, and sometimes in May. 

 This is also the season of ovipositing. Only in two instances have I 

 been able to get reports of females in " berry" at a later period than 

 June ; and in each case but a single specimen was found. 



I have frequently found large males travelling considerable distances 

 overland in the month of March to neighboring streams and ponds doubt- 

 less in response to the sexual instinct which is remarkably dominant at 

 that time. In many cases the boldness with which such journeys were 

 prosecuted in open daylight proved a fatal adventure, the daring subject 

 falling a victim to the rapacity of the ubiquitous crow, to whose insatia- 

 ble maw it appears to afford the special *' delicacy of the season." 



Finally, there appears to be considerable variation in different quar- 

 ters as to the time of ecdysis. 



Prof. Huxley, following the accounts of the older French observers, 

 Reaumur, M. Carbonnier, and M. Chautrau, states this process as oc- 

 curring ordinarily in adults in early autumn ; or in the males perhaps 

 twice during the year, in June and September. It has been reported as 

 taking place in the cray-lishes of the west coast of Africa in December ; 

 at which time the " sqfl craws," as they are then called, are in great 

 demand as an article of food. 



While it has not been my fortune to directly observe the animal un- 

 dergoing the throes of this ordeal, I have yet found them repeatedly 

 within a short time of its occurrence, and while they were still quite 

 limp and defenceless. This has invariably been in the spring, chiefly 

 in May and early June. Furthermore, the cast skeletons are very com- 

 mon in the creeks, where the animals abound, during the spring and 

 early summer in such perfect condition as to be easily mistaken for the 

 living cray-fish. I have frequently so mistaken them while foraging 

 for biological materials, and more than once have been undeceived only 

 after a dextrous dip of the net brought the empty form to the surface. 

 Now it is perfectly certain that no skeleton vacated during the previous 

 autumn would so completely withstand the disintegrating action of the 

 frosts and floods of winter and spring as to show no traces of the 

 slightest disarrangement or disorganization of even the most delicate 

 parts. 



The brief outline and comparison of observations submitted in this 

 review show considerable variation, if not discrepancy, in the records 

 of different observers. Some reasons for this have already been indi- 

 cated. Aside from the possible errors always likely to arise out of what 

 has been termed the personal equation of the observer, the variations 

 noted are not specially remarkable. Moreover, when we take into con- 

 sideration the widely diflerent conditions of the environments under 

 which the observations noted were made, and also the usually slight 

 varations of even closely related genera and species under similar, or 

 but slightly different conditions, the differences of habit are not more 

 than would ordinarily be expected, notw^ithstanding the remarkable and 

 profound differences exhibited by the various orders of the class. That 

 there remains much to be done in order to a thorough acquaintance of 

 the life-histories of the Crustacea is certainly obvious. If this sketch 

 shall in anywise contribute thereto it will not have been in vain. 



Miami University, April 15, 1890. 



