478 SPIO MARTINENSIS. 
6 
(Southern). It is abundant between tide-marks, Plymouth, and in clean, hard sand in the 
estuary at Exmouth (Allen). 
Extends to Swedish (Hliason) and northern waters. 
Southern observes that this form differs from what he had described im the ‘ Proceedings 
of the Royal Irish Academy’ as Spo seticornis, Fabricus, from Clare Island. In Pygospio 
seticornis the head is bluntly bifid, though when seen laterally it is conical. The branchize 
commence on the first or second segment, and are large about the twelfth or thirteenth. 
The tail ends in two larger and two smaller 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 a scoop-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 segment, and are boldly curved 
in the anterior region. Hhason shows the ventral bristle of the fiftieth segment as devoid 
of the granular structure seen in Spo filicornis. 
(iirsted describes the species as having two series of parallel eyes, the tentacles not 
alternate, the segments devoid of black pigment ; ligulate branchize in the middle of the body, 
but diminishing and disappearing at either extremity. There can be little doubt that 
(Ersted’s form was a Pygospio. It is not the Nerevs seticornis of O. Fabricius. 
This form closely resembles Pygospio elegans, Claparéde, 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-examination. Leschke gives an account of two stages of what he considers 
to be the pelagic larvee, which occur likewise in British waters, though their identity has 
not been satisfactorily tested. 
SPIO MARTINENSIS, Mesnil, 1896. Plate CXX XVII, fig. 3—tenth foot ; 3a—twentieth foot. 
Specific Characters—Head trilobed, a rounded median lobe projecting in front and 
supported by two lateral lobes. ‘Two or four eyes at the posterior border. Short median 
tentacle on the prostomium, and a short median ridge ends posteriorly in a process. Body 
generally like that of Spzo, and about 3 cm. long and 1—2 mm. broad, with eighty-five to 
ninety segments (Mesnil), ending in a dorsal anus with four foliaceous cirri. Colour salmon- 
tint, with red lines from the blood-vessels, and dark-brown pigment in transverse rows on the 
seoments. First foot bears a ventral tuft of finely tapered bristles with very narrow wings, 
and a large branchia which overlaps that of the opposite side. Winged hooks appear in the 
eleventh foot and continue to the posterior end, as do the bristles, and in these the main 
fang comes off at more than a right angle, and has a single spike above it. 
* SYNONYMS. 
1896. Spio martinensis, Mesnil. Bull. Sc. France et Belg., p. 122, pl. vii, figs. 1—20. 
1914. ,, a Southern. Proc. Roy. Irish Acad., vol. xxxi, No. 47, p. 95. 
OND, 55 % McIntosh. Ann. Nat. Hist., ser. 8, vol. xv, p. 1. 
ION, 55 * Mesnil and Caullery. Compt. Rend., clxv, p. 284. 
19205 > McIntosh. Ann. Nat. Hist., ser. 9, vol. ix, p. 17. 
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