128 



CHAS. B. WILSON. 



Egg-laying. 



The breeding season extends over about two montbs or ten 

 weeks. Some of the females begin laying by the 10th of 

 June, while others delay till the 20th or 25th of August. In 

 general those which live in sheltered coves or bays lay earlier 

 than those found in exposed positions_, while the nearer low 

 water mark the worm is found the later will its eggs be 

 deposited. By changing the locality^ therefore, from which 

 the eggs are obtained, fertile ones can be secured throughout 

 the entire two months. Although Casco Bay is but little 

 north of Long Island Sound, the above dates are radically 

 different from those given by Coe (15), who states that in the 

 vicinity of New Haven the breeding season extends over the 

 month of April, and that by " the first of May nearly all the 

 genital products have been discharged.^^ This serves to 

 emphasise still farther the marked differences which have 

 been noted in the breeding seasons of other Invertebrates 

 from these two localities. 



Burger (13) states that Nemertean eggs are usually joined 

 together in strings or balls, but that they are rarely laid 

 singly. Metschnikoff (35) gives Lineus lacteus as one of 

 these rare instances, but he tells us nothing whatever as to 

 the manner in which they are laid. 



From the rapidity with which the outer gelatinous envelope 

 disappears when the eggs are placed in water for artificial 

 fertilisation, it would be naturally inferred that the eggs, if 

 not laid singly, at least separated very quickly, since this 

 envelope would be all that held them together. That this is 

 what actually occurs was proven by observation. The first 

 lot of eggs laid in the aquarium (cf. p. 113} were found 

 early in the morning already fertilised. A day or two 

 later the process was repeated while the aquarium was being 

 watched, also early in the morning. A stream of eggs was 

 noticed coming out of the opening of one burrow, while from 

 another burrow at the opposite side of the aquarium sperms 

 were issuing. 



