644 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 
Larva with anterior broad 
chaetigerous, middle narrow 
chaetigerous, and _ posterior 
narrow achaetigerous body- 
regions; a pair of tentacles 
present, ultimately papillate 
on the anterior surface, and 
each in early stages continued 
into a remarkably long larval 
tentacle set with spine-like 
papillae; devoid of cilia; (the 
earliest stages known, accord- 
ing to Claparéde, have a wide 
anterior gaping mouth, and 
are polytrochal) : 
Nototrochs present on all 
segments, gastrotrochs on 
sepments 5, 7, 10, 13,15, 17, 
etc.; much black pigment; 
(the more advanced larvae 
show the enlargement and 
special setae of the 5th seg- 
ment) : 
=I 
Distribution of cilia not as 
above; or pigment absent: 
S. Ramified stellate patches of 
intense black pigment 
present : 
No such patches present; black 
pigment arranged in dis- 
continuous transverse bands: 
9. Larva very small, with three 
pairs of black  eye-spots; 
provisional setae of Ist 
segment twice the length 
of the body: 
Larva very small, with one pair 
of eye-spots which disappear 
in spirit; provisional setae 
shorter than the last: 
Magelona. 
(Polydoridae. ) 
(Spionidae.) 
Polydora A. 
Polydora B. 
Spio. 
Spionid C. 
(8) 
(9) 
