634 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 
forwards so that the now funnel-shaped oesophagus passes 
backwards instead of forwards, to open into the stomach, 
which on the third day comes to open to the exterior 
through a short rectum exactly as in the Port Hrin form. 
Wilson also describes (loc. cit., pp. 286-8; Pl. XXII, 
fies. 80-88; Pl. XXIII., fig. 9) a few later stages of a 
larva provisionally referred by him to the genus 
Spiochaetopterus. The larvae of Telepsavus and 
2? Phyllochaetopterus are described by Claparéde and 
Mecznikow (1869: pp. 178-182; Pl. XIV., figs. 1-1H, and 
2) and by Fewkes (1885: pp. 177-180; Pl. TLl., figs: 
5-19). The caudal appendage is present in both forms; 
only one mesotroch is present throughout the development 
of the former. 
JIT:—TEREBELLIFORMIA. 
AMPHICTENID ®. 
Pectinaria (Pl. IV., figs. 40-47).—Metatrocho- 
p hore I .—No Trochophore of this worm has been seen, 
but the youngest Metatrochophore (250% by 190) shows 
little trace of segmentation and can be only just beyond 
the trochophore stage. It is ovate in shape, the posterior 
end being slightly narrower than the anterior. The 
prostomium is rounded and covered with black pigment 
spots which tend to be aggregated into a band encircling 
it just in front of the prototroch, which is slightly raised 
above the mouth (fig. 40). Segmentation is only indicated 
by unilateral transverse rows of pigment spots on the 
posterior part of the larva. The anus is bordered dorsally 
and laterally by a horseshoe-shaped ridge thickly covered 
with pigment spots. 
A slightly older larva (300 by 200) is shown in 
Pl, IV., fig. 40; this difters from the previous stage in 
