14 



NEPHTHYS (L3ECA. 



of long delicate simple bristles without the marked blade of the serrated forms, and 

 tapering to a fine point. They are of great length, are pale (Plate LXXVI, fig. 1 e), and 

 never attain the diameter of the more distinctly serrated forms, a few of which are found 

 at the ventral margin of the inferior division and elsewhere. The latter are recognised 

 by their yellowish hue, a colour which enables even broken fragments in the upper 

 division to be readily recognised. Why these long, smooth, or very minutely serrated 

 bristles should be developed in this way is unknown. ~No sexual elements were 

 observable in the examples after preservation. No change occurs in the barred bristles. 

 It may be noted that Ehlers likened the foot in Nevldhys to the epitokous condition in 

 Nereis. 1 If such be an epitokous condition it would not therefore be complete. 



The weight to be placed on small changes in the development of parts of the foot, 

 e. g. enlargement of lobes, is not yet sufficiently understood. 



Reproduction. — At the reproductive season (e. g. towards the end of March at St. 



so 



ov. 



vm orrv ric. 



Fig. 38. — Section of a female Nephthijs cseca distended with ova. s o. Segmental organ (nephridium). d. Alimentary 

 canal, d.m. Dorsal longitudinal muscle, d.v. Dorsal blood vessel. n. c. Nerve cord. o.m. Oblique 

 muscles, ov. Ova. p. v. Perivisceral (ccelomic) space, v.m. Ventral longitudinal muscles. 



Andrews) the body-cavity is filled with large ova (Fig. 38), which in section are found 

 chiefly below the gut and in the cavities of the feet, though they also pass above the gut. 

 The changes in the thickness of the muscular development in this condition may be 

 ascertained by contrasting this figure with Fig. 34. In the males a similar condition 

 prevails, the sperms likewise appearing above the gut and the dorsal vessel. 



The larva3 of JNTephthys have been long known, though their association with the 

 genus was not always understood. Thus a larva described by Busch 2 apparently agrees 

 with a stage figured by Claparede and Mecznikow with curved tufts of cilia. 



Claparede and Mecznikow 3 found several stages, though they were uncertain as to 

 the relationships of some, and the same may be said in regard to Fewkes. 4 



1 ' Borstenwiirmer/ ii, p. 584. 



2 'Beobach./ p. 68, Taf. viii, fig. 7. 



3 'Beitrage/ 1869, p. 187, figs. 3, 3a, and 3d. 



4 < Stud./ 1884—85, p. 180, Plate iv, figs. 1—12. 



