No. 447-3 BREEDING HABITS OF CRAYFISH. 



The eggs must have passed out of the oviducts in a short 

 space of time and have been received into the basket formed by 

 the bent up abdomen, a basket full of glair that would protect 

 the eggs from contact with the water. That this glairy sub- 

 stance is the secretion of milk-white cement gland areas seems 

 certain ; when the material about the eggs is examined under 

 the microscope it contains droplets like those found in the 

 secretion of the cement gland. 



The probable mode of laying may be inferred from the above 

 observations and from the following considerations. It wc place 

 a female crayfish upon her back and bend the alxlonicii forward 

 over the thorax as far as possible we can see that if tlic eggs 

 were forced out by the contractions of the oviducts they 

 would issue in two streams from the mouths of the oviducts 

 which are on the bases of the antepenultimate legs : they would 

 then emerge into a median triangle-like depression formed by 

 the thoracic sterna and this would form an inclined plane down 

 which the eggs would flow into the basket formed by the 

 abdomen, which is on a lower level. When first seen the eggs 

 were very soft, apparently liquid and most easily deformed and 

 indented yet coming rapidly back to a spheroidal shape, owing, 

 partly at least, to the presence of a thin membrane. At first 

 the eggs were not spherical but pear-shaped or elongated ; but 

 when put into hardening liquids they took on a .spherical form. 

 When the female is lifted out of the water the soft eggs crowd 

 together and have polyhedral shapes as if liquid, or plastic. In 

 the position assumed by the female it would seem that gravita- 

 tion acting upon the liquid eggs would bring them into the 

 abdominal basket. 



The female that has laid continues to hold the abdomen flexed 

 and the eggs are contained in the basket of glair for some hours. 

 As seen from the side sucK a female, Fig. 6, seems to have 

 an apron of glair stretching from the second legs and that part 

 of the thorax back to the expanded tail fan and somewhat 



bellied downward as time goes ( 



able rhythmic habit was observed in several female 



rhythi 



regarded as a necessary element 

 eggs. This performance lasts sev 



in the future success of the 

 eral hours and may be spoken 



