1899] EPITOKOUS FORMS OF ANNELIDS 383 



the Polychaets. The authors cite the peculiar cases of parasitism of 

 one annelid in another, as Lumbriconereis in Marphysa, one of the 

 Eunicidae. Krohn, however, found a viviparous Syllis at Nice, in 

 which* the embryos in the body-cavity occupy a third or a fourth of 

 the length posteriorly. Levinsen describes briefly a similar instance 

 in Syllis incisa. Claparede and Metchnikoff found a viviparous Cir- 

 ratulian at Naples, the young having two eyes, two pairs of branchiae, 

 and similar touches of pigment to the adult. The authors, as already 

 mentioned, indicate that their form A {Dodecaceria) is viviparous, but 

 further observations are needed. Viviparity, again, occurs in Nereis 

 dvcersicolor and N. dumerilii. The former, a protandrous herma- 

 phrodite, was found by M. Schultze to produce reddish-brown ciliated 

 pyriform larvae furnished with a mouth and incomplete intestine. 

 The segmentation of the eggs has been seen by Schroder ; while 

 Mendthal thinks they may only be exceptionally developed in the 

 interior of the mother. The authors suggest that it may be a case 

 of self-fertilisation. The viviparity of Nereis dumerilii was observed 

 by Metchnikoff in a hermaphrodite form, yet though the authors 

 found many at La Hague, no trace of the condition was seen, so that 

 this feature may be only occasional, as in the Serpulidae. They also 

 incline to the opinion that in Dodecaceria concharum (A), in Syllis 

 vivipara, and S. incisa, in Cirratulus ehrysoderma, the forms are 

 unisexual, and that, therefore, parthenogenesis occurs. As formerly 

 stated, however, further observations are required before certainty is 

 reached. 



It will thus be seen that while the able authors have increased our 

 knowledge considerably in regard to Dodecaceria, yet even in this 

 form several important features remain for future investigators, 

 such as the exact relationship of the three forms A, B, and C, and 

 the development of each. These problems rest with southern 

 observers, since Dodecaceria is rather rare in our colder northern 

 waters. 



The epigamous condition in annelids has, perhaps, its analogues in 

 the medusoids of the Hydrozoa, the strobila of the tape-worm, the 

 imago and specially the queens of certain insects, and the changes in 

 the male cephalopod. 



The relation of the changes in certain vertebrates is not so clear, 

 but yet there is a thread of analogy in the alterations of the mandible 

 of the male salmon, the coloration of the lump-sucker and other fishes 

 at the breeding season, the changes in the air-sacs of certain 

 amphibians, in the plumage of birds, in the passage of the testes 

 outwards in certain mammals at puberty, and the development of 

 fat, hair, and horns on certain reoions. 



The free discharge of the ova from the ovaries of the higher forms, 

 their passage along the oviduct to the uterus, the development of the 

 embryo in this organ, and lastly its extrusion externally, are only 



