No. 447 ] BREEDING HABITS OF CRAYFISH. 



one second. The endopodites of the third maxillipcds and 

 the anterior three pairs of legs are sometimes swim- back 

 and forth also. Finally a peculiar secretion is passed trnth 

 and the eggs are then laid. This secretion is iurmsiicd bx ihc 

 "cement glands" of the under side of the tcinale and needs 

 special notice. One of the things that make mueh bu the 

 clean appearance of the under side of the abdomen wiuii the 

 female is about to lay is the ])resem-e of lai-e milk-white 

 areas on the basal parts of both endopochtes and e.\opo(htes 

 of the sixth pair of abdominal appendages, b)rming \ei v con- 

 spicuous white patches when the tail fan is e\])an(led. The 

 other pairs of pleopods are pretty uniformly milk white but the 

 endopodites are more ctensely white and the glands m their 

 terminal parts are somewhat segmentally arranged. The 

 sternal plates between all six pairs of pleopods also stand out 

 as milk white areas. Anterior to the abdomen the only milky 

 gland areas are the sternal plate of the last somite, the annulus 

 and the edges of the two flaring sternal plates anterior to the 

 annulus. At other times of year these " cement gland " areas 

 seem inactive or at all events inconspicuous. When a portion 

 of one of the milk areas was removed from the tail fan 

 or from any of the smaller pleopods it furnished, under pres- 

 sure, a milky material which swelled up in water as a clear 

 jelly containing minute spherules as seen under Zeiss 2. D. 

 and as a somewhat milky glair as seen with the naked eye. 

 When first pressed out from a piece of the glandular area the 

 secretion also contains the minute spherules or droplets. 



In one case a female was seen to stand with the body 

 raised high above the bottom of the tank and to wave the 

 pleopods back and forth while they gradually became covered 

 with a clear slime or glair. Forty-five minutes later, at i . 1 5 ]). m. 

 the female was lying upon her back and all the eggs had 

 passed out of the oviduct. The general appearance of this 

 female that had just laid is indicated in Fig. 5. Lying u])on 

 the back with the limbs stiffly extended and no motion visible 

 the creature seems dead unless the strongly bent abdf)men 

 suggest muscular contraction. Passing forward from the 

 widely expanded tail fan is a faint film of slime or glair that 



