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larger Myzostomes. The testes fill out much of the body, but caryo- 

 kinetic figures have appeared in the ovaries and the triplet cells are 

 found in the uterus and its incipient branches. A very few of these 

 cells are also found attached to the dorsal walls of these branches. 



3) Still older and larger individuals (about one-third or to two- 

 thirds grown) have ovaries and testes about equally well developed. 

 Both mature spermatozoa and ova capable of normal development can 

 be readily pressed from the body. These individuals are , therefore, 

 functional hermaphrodites. 



4) The largest and oldest individuals are full of ripe and devel- 

 oping ova but the testes are much reduced and in some cases appear 

 to be absent, although a few ripe spermatozoa of uncertain origin are 

 found scattered through the body cavity or massed together in a nar- 

 row space in the mid-dorsal line over the uterus. 



Thus M. glahrum is throughout its life hermaphrodite but func- 

 tionally male in its early youth and functionally female in its old age. 

 Beard overlooked the ovary oîM. glahrum and, apparently too much 

 absorbed in drawing a parallel between Myzostomes and Cirripedia, 

 failed to examine a sufficient series of individuals of different aares. 

 V. Graff was right in regarding the socalled »complemental malese as 

 young specimens which had attached themselves to the backs of the 

 first settlers on the disc of the Antedon. The main purpose of this 

 attachment is not to fertilize the eggs of the succumbent hermaphro- 

 dites — although this very probably occurs — but to be near the food- 

 current passing into the mouth of the Crinoid. Only after the death 

 and dissolution of the old Myzostomes do the young ones appear to be 

 able to attach themselves directly to the lips of their host. 



Only a few specimens of ilf. alatum were examined, but the con- 

 ditions appear to be the same as in M. glahrum. In both species there 

 is only a single pair of ovaries. Pr ouho has shown that M. alatum is 

 protandric, but like other investigators he has failed to detect the true 

 ovaries which are also present in the »complemental males« of this 

 species. 



In M. cirriferum , which is an actively moving species occurring 

 in considerable numbers on the arms and disc of Antedon rosacea, the 

 conditions are very similar. There are, however, two pairs of ovaries in 

 this form. In the youngest specimens which I have sectioned only the 

 testes contained mature reproductive cells. As the Myzostome grows 

 the ova make their appearance in the body cavity and ultimately the 

 individuals contain great masses of mature ova and spermatozoa side 

 by side. I am not sure that M. cirriferum ultimately reaches the con- 

 dition in which the testes are greatly reduced in number or wanting; 



