LYCASTIS QUADRATIC KPS. 383 



rather the reverse, is just as evident among the Polychaeta as 

 elsewhere in the animal kingdom. As the macroogenous Clado- 

 cera and Aphids occupy but a lowly position in their respective 

 classes, and as the same is true of the auks, guillemots, and 

 apteryx among birds, so we find the macroogenous Polychaetes 

 are all of puny size, comparatively simple organization, and one 

 is hermaphroditic. In what, then, lies the advantage of produc- 

 ing so few ova ? Unquestionably, there can be greater storage 

 of food stuff per ovum if the eggs be few, and upon this the well- 

 known law of biogenics, namely, the greater the inheritance of 

 stored-up nutriment from the parent, the greater the chance of sur- 

 vival for the offspring, is based. Whether the young are launched 

 into the world as typical, free-swimming trochophores, as modified 

 trochophores, or in the form of young worms, has not been 

 ascertained in any of these interesting forms. With so large a 

 store of food-yolk a direct or nearly direct development is prob- 

 able ; and the very limited number of eggs presupposes such 

 protection through the early stages that a very high percentage 

 of the young come to maturity. 



The occurrence of incipient or occasional hermaphroditism in 

 a few species that are functionally or usually bisexual {e. g., 

 Macellicephala violacea, Nereis diversicolor, and Platynereis du- 

 merili) is of especial interest. In a bisexual form like Macelli- 

 cephala the very beginnings of hermaphroditism may be seen. 

 According to Wiren ('07) undoubted traces of male gonads are 

 never found in female specimens. In those which are function- 

 ally male, however, all the gonads contain groups of ova. As in 

 the female, they are each surrounded with a follicular membrane. 

 Free ova also occur in the coelom, but no mature ones of full 

 size and rounded form. It is impossible to be sure from the few 

 observations whether this species is actually an incipient or an 

 occasional hermaphrodite. 



The most carefully-studied hermaphroditic Polychgete is prob- 

 ably Ophriotrocha piierilis. In this species, according to Korschelt 

 ('93) it is often difficult to distinguish between males and females ; 

 but in the older specimens even in the living state the microscope 

 reveals the ova or spermatozoa in the ccelom. Nevertheless, 

 hermaphroditism is the prevailing condition. Says Korschelt 



