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SCIENCE 



[N. S. Vol. XXIX. No. 139 



small eggs and must pass through a long and 

 fascinating series of changes before the adult 

 form and habit are attained. It should be 

 added, however, that in the modern zoologist 

 the lure of the sea is strong, even when cray- 

 fish abound in his back-yard and burrow all 

 over his lawn. Eoesel indeed complained of 

 the neglect which obscured the life of com- 

 mon things in his day, and recalled the old 

 Latin proverb to the effect that what is daily 

 seen is little heeded. 



In the present monograph, as well as in his 

 earlier papers. Professor Andrews has thrown 

 a light on many obscure questions, and has 

 probably added more to our knowledge of the 

 crayfish family life and general natural his- 

 tory than all previous observers combined. 



For the first time the habits and develop- 

 ment of an American species of Asiacus, 

 from the Pacific coast, are described, while 

 its young have been reared to a length of two 

 inches and an age of five months, when 

 they have molted twelve times, and reached 

 essentially the adult state. The behavior of 

 these young is subjected to a careful analysis, 

 and the text is illustrated by a series of excel- 

 lent pen drawings showing in detail the slight 

 but important changes which ensue in the 

 body proper and its nineteen pairs of append- 

 ages during the first three stages, or until the 

 young have become independent of their 

 mother. Careful drawings to a uniform scale 

 have seldom or never been made to represent 

 the complete metamorphosis of any crusta- 

 cean, and students of this important class will 

 appreciate their value in the present ease. 



The habits and development of Cambarus 

 affinis are treated in a similar descriptive and 

 pictorial way, and the author devotes a chapter 

 at the end to the weighing of the differences 

 and agreements found in the two genera, and 

 to certain speculations upon the possible 

 origin of their diverse dependent stages and 

 family life. 



Astacus leniusculus lays its eggs, to the 

 number of five hundred in the cases observed, 

 in autumn, probably in October, and carries 

 them attached to its pleopods all winter; 

 these eggs are dark in color, and very large 



for a crustacean, having a diameter of twa 

 and one half millimeters, which accords with 

 the precocious character of the young at birth. 

 Hatching took place in late April and early 

 May, and extended over several days. The 

 young leave the egg in a relatively advanced 

 but quite helpless condition, and if expelled 

 from the mother, as in the case of the marine 

 lobster, they would perish from lack of pa- 

 rental care, for they present a curious com- 

 pound of embryonic, larval and adult char- 

 acters. It is at this juncture that the peculiar 

 family life of the crayfish has been developed 

 to tide the young over a helpless period of 

 infancy to complete independence, and the ac- 

 count of this interrelation of parent and 

 child, and the correlated structures and in- 

 stincts upon which it is based constitute the 

 most interesting part of Professor Andrews's 

 work. 



The family relation in this Astaciis endures 

 for over a fortnight or until the little crayfish 

 has molted for the second time, and is de- 

 pendent upon a complicated chain of events, 

 which suggests the story of the old woman 

 who went to market to buy a pig. If the egg- 

 stalk does not adhere to a "hair" of the pa- 

 rental swimmeret or to another egg; if the 

 two egg-shells are not themselves adherent; 

 if a certain delicate thread, which is spun as 

 it were from an embryonic molt shed at hatch- 

 ing time, does not itseK stick on the one 

 hand to the telson of the yoimg, and on the 

 other to the inside of the inner egg-shell and 

 thus tether the little one to its mother; if,, 

 again, a little later, when its leading string 

 has broken, this young one has not been enter- 

 prising enough to seize and "hook on" to 

 some part of the egg-glue with its great for- 

 ceps, the tips of which have been bent into 

 fish-hook form — it comes to certain grief. 

 The result is fatal, at whatever point the 

 chain weakens and snaps. 



A few hours after hatching the helpless 

 little crayfishes, still dangling from the " tel- 

 son-threads," which secure each to the pa- 

 rent, begin to flap their abdomens, and to 

 open and close their big hooked claws. In 

 this way they manage to seize the old stalk of 



