376 IV. C. AT INTO SB [may 



characteristic elongation of the bristles in summer, and is found amongst 

 the rocks rather than amongst the sand. So different is the aspect of 

 this form that it has been described as a different species. 



In the Phyllodocidae Malmgren describes a Enlalia (E. 'problem a), 

 from Greenland, in which the middle and posterior feet have greatly 

 elongated simple bristles. De Saint-Joseph mentions two ripe females 

 of Mystides limbata which, besides the ordinary bristles, had very long- 

 tufts of simple bristles in the middle of the body and also enlarged 

 eyes, absent in unripe individuals. A similar condition is seen in the 

 Eidalia gracilis, Verr., of Webster and Benedict. The large-eyed species 

 described by the writer in the " Challenger " volume, however, gave no 

 evidence of a pelagic habit. 



In the Hesionidae Malaquin indicates that an epitokous condition 

 occurs in Kefersteinia cirrata, and Webster and Benedict describe 

 Hcsione gracilis as bearing very long dorsal bristles. 



The Syllidae, again, offer well-marked examples of epigamy, some 

 at sexual maturity assuming the large eyes, long natatory simple 

 bristles and other characters. In certain forms it is the males only 

 which are affected, in others the females, in which the long natatory 

 bristles are shed after the escape of the eggs. Moreover, these bristles 

 are confined to the posterior region of the body in which the repro- 

 ductive elements are developed in the form of stolons. In Autolytus 

 and allied forms the stolons so differ from each other as to have been 

 included in different genera. An Exogonc, again, is described by 

 Malaquin which presents now epigamy, now schizogamy (separation of 

 buds). Haswell found a Syllis which, while showing eggs anteriorly, 

 developed sperms posteriorly, the latter region developing a head and 

 swimming away as an independent form. While this family, therefore, 

 shows many illustrations of epigamy, it is one in which the most 

 remarkable illustration of branching in an adult annelid occurs, viz. in 

 Syllis ramosa of the " Challenger." 



In the Nereidae the epitokous condition is a distinctive feature, 

 resulting in the transformation of a Nereis into a Heteronereis. The 

 external modifications consist in the great development of the eyes, the 

 alteration of the form of the head, and the remarkable changes in the 

 feet, which are complicated by lamellae and foliaceous cirri as well as 

 by modifications of the bristles. The anterior region of the body 

 remains more or less unaltered, but, in the transformed parts behind, 

 the sexual products accumulate. As Perrier aptly says, it is a cater- 

 pillar in front, a butterfly behind. Moreover, the males are different 

 from the females. 



Some of the finest Nereids, such as the splendidly tinted Alitta 

 virens of Sars, are epitokous forms, and the complexity of the changes 

 in such species as Nereis clumerilii are full of interest. 



No example is yet known in the Lumbrinereidae, but in the 

 Eunicidae, the well-known Palolo viridis of Samoa and Tonga in the 



