POLYCH AT LARVA. 615 
in Spioniform larvae, much longer than those of the 
secom@apair. Leschke (1903: p. 103; Pl. VI., fig. 10) 
has also described the Trochophore of this species; his 
account is in close agreement with that of Cunningham 
and Ramage. OClaparede and Mecznikow (1869: PI. 
XII., fig. 4) figure a two-segment larva of this species, 
still invested in the vitelline membrane; it is apparently 
of about the same age as that figured by Cunningham 
‘and Ramage in fig. 2 G of their Pl. II. Claparede and 
Meeznikow state that the further development is broadly 
the same as that of “ Nereen (falschlich Leucodoren) 
») 
Larven von Normandie,” and only figure one other stage, 
this having over thirty segments. This larva is at once 
distinguished from the Spionid larvae of the present paper 
by the large prickles on the provisional setae of the first 
segment. The figures given by Cunningham and Ramage 
OGemener fl XXXVIT., figs. 2 1, 2 J) show “a later 
stage [12-segments; not described in the text] of the 
of NV. cerratulus which has developed along very 
d 
larva ’ 
different lines from this larva, but resembles in some 
detail the larvae of Polydora (see below, p. 627). | 
Spionid ©. (Pl. III, fig. 35). This is an extremely 
common form, characterised by its small size (about equal 
to that of similar stages of the Spzo described above), 
long slender setae, and single pair of eye-spots, which are 
situated slightly on the ventral surface and which always 
disappear in spirit. I have only been able to make a 
hurried examination of the hving larva. 
Metatrochophore.—tThe head is rounded and 
bears a tuft of apical cilia and one pair of red eye-spots. 
The prototroch is probably still complete at this stage, as 
the characteristic cephalic larval organs of the Spionidae 
do not seem to have developed as yet; it encircles the 
larva in its broadest part, which is 150 in diameter. 
