POLYCH ET LARVA. 605 
retracted into pits in the body-wall. They are all 
compound, but do not now show sufficiently clearly in 
balsam to allow an accurate drawing to be made. 
Eunicid Metatrochophores very similar to the above 
have been described by Hacker (1896: pp. 78-9; PI. III., 
feeeewand 1698: p. 9; Pl. I. fig. 2). His 1896 paper 
includes a description and figure of the Nectochaeta, as 
well as the Metatrochophore of the Naples species. 
Other LKunicid larvae have been described by 
Claparede and Mecznikow (1869: pp. 182-4; Pl. XV., 
fies. 1-LH—? Lumbriconerets. And pp. 184-186; Pl 
XIT., figs. 2-21—Ophryotrocha), Wilson (1882: pp. 288- 
201; Pl. XXI., figs. 89-92; Pl. XXIII., fig. 10—a very 
complete account of the development of Diopatra cuprea), 
Bemkess (isso: pp. 197-201; Pl. VII. and Pl. VIILI., 
figs. 1-3—Lumbriconereis; stated to be generically 
different from the ? Lumbriconereis of Claparéde and 
Meeznikow), Braem (1893: pp. 217-221; Pl. XI., figs. 
32-36—O phryotrocha) and Korschelt (1893: pp. 237-242; 
Pl. XIII., figs. 12-15—Ophryotrocha). All these larvae 
agree in the suppression of the trochophore stage; but 
this is apparently due to the first portion of their develop- 
ment taking place within a mass of jelly, and is not at all 
exclusively characteristic of the Eunicidae (see Hacker, 
1896). With the exception of Ophryotrocha, there is, 
however, a marked resemblance between them in general 
form. 
Il—SPIONIFORMIA. 
The larvae of Spioniform worms (with the exception 
of the Chaetopteridae, whose well-known ‘“ mesotrochal ”’ 
larvae form a well-defined group), are characterised by 
the presence of long capillary provisional setae, of which 
those of the first segment considerably exceed the others 
