Gatty Marine Laboratory, St. Andrews. 17 
anterior margin most minutely serrated, the serrations 
readily escaping detection even under high powers. The 
posterior border is concave, and the base is convex in front, 
concave posteriorly (O.G. curve). 
Potts considers that the conical peristomium is primitive, 
and that the formation of the peristomial funnel is a direct 
adaptation to microphagous habits. The prostomium is a 
definite structure, but varies in the several species, being 
better developed in some than in others. It is_ better 
developed in P. anglicus than in P. elioti, Crossland, from 
Zanzibar. 
In the Spionide, Southern found Pygospio seticornis 
(Cirsted) on the West Coast of Ireland, and observed that it 
differs from what he had described in the ‘ Proceedings of the 
Royal Irish Academy’ as Spio seticornis, Fabricius, from 
Clare Island. In Pygospio seticornis the head is bluntly 
bifid, though when seen laterally it is conical. The 
branchiz commence on the first or second segment, and are 
large about the twelfth or thirteenth. The tail ends in 
two larger and two small cirri, somewhat like Pygospio 
elegans ; though in one example the four caudal cirri were 
about equal. What was sent as a young specimen presented 
only two ovate lobes at the tail. The anterior bristles are 
stouter and more boldly curved, with ascoop-shaped lamella 
in front of them, whilst those at the tail are as usual in the 
group and nearly straight. There are five or six tufts of 
these. 
The hooded hooks commence on the seventh bristled seg- 
ment, and are more boldly curved about the anterior third. 
There can be little doubt about Cérsted’s form being a 
Pygospio. It is not the Nereis seticornis of O. Fabricius. 
(Hrsted describes the species as having two series of 
parallel eyes, the tentacles not alternate; the segments 
devoid of black pigment; ligulate branchiz in the middle 
of the body, but diminishing and disappearing at eitlicr 
extremity. 
This form closely resembles Pygospio elegans, Claparede, 
with the exception of the arrangement of the branchiz, and 
has been a puzzle to many students of the group. It is in 
need of careful re-exanmnation. Leschke gives an account 
of two stages of what he considers to be the pelagic larvae, 
which occur likewise in British waters, though their identity 
has not been satisfactorily tested. 
Spio martinensis, Mesnil, comes from Dublin, Clew, and 
Blacksod Bays, Ireland (Southern). This is a much larger 
Ann. & Mag. N. Hist. Ser. 9. Vol. ix. 2 
