474 SPIOCHATOPTERUS TYPICUS. 
SYNONYMS. 
1878. Scolicolepis (2) Jeffreysti, McIntosh. Trans. Linn. Soc., ser. 2, vol. i, p. 506. 
1879. Aricidea fragilis, Webster. ‘Trans. Albany Inst., vol. ix, p. 55, pl. ix, figs. 127—132. 
1909. 3 Jeffreysti, Cerruti. Mitt. Zool. Stat. Neap., Bd. xix, p. 469, Tav. xviii and xix. 
1914. 5 Southern. Proc. Roy. Irish Acad., vol. xxxi, No. 47, p. 93. 
1922. ss 53 McIntosh. Ann. Nat. Hist., ser. 9,-vol. ix, p. 15. 
Habitat —Ballynakill Harbour, 2—4 fathoms, Clew Bay, 24 fathoms (Southern). 
Distribution‘ Valorous” Exped. (McIntosh); Mediterranean (Cerruti) ; United States 
of America (Webster and Benedict, Treadwell). 
In transverse section the body toward the anterior third presents an ovoid outline. The 
cuticle 1s well-marked, and the hypoderm thick, especially along the entire ventral surface. 
The dorsal longitudinal muscles are considerably less than the ventral, and a large gap occurs 
in the median raphe. The ventral longitudinal muscles are separated by a central interval, 
at the bottom of which the nerve-cords lie, the oblique muscles passing over their summit. 
The circular muscular coat is much developed, but the lateral vertical bands supplement it. 
The alimentary canal is rounded in section, has a thick circular muscular coat, and the 
glandular inner surface is richly ciliated. 
It is probable that the Arecidea quadrilobata, the A. nolani of Webster and Benedict, 
and the A. alata of Treadwell belong to this species. The Crrrophorus branchialis of Ehlers 
is also an allied form. 
Famity CHA&TOPTERIDA. 
Genus SPIOCHATOPTERUS, Sars, 1856. 
Cephalic lobe small, rounded, eyeless; peristomium forming a funnel-like process—in the 
middle of which is the mouth. Two long, grooved tentacular cirri resembling those of a 
Spro. Body slender, elongate, in three regions, anterior, middle and posterior, the first 
with nine bristled segments, the second of two long segments having only foliaceous lamellee 
with included capillary bristles dorsally, and the third of numerous segments with conical 
feet. Posterior segments with very minute thin hooks. Tube hyaline, brittle and ringed, 
attached by one end, unbranched. 
SPIOCH ETOPTERUS TYPICUS, Sars, 1856. Plate CX XXVIII, fig. 14—hook. 
Specific Characters—Head small, rounded, devoid of eyes. Peristomium forming a 
funnel, with the mouth in the centre, and with a small process on each side of the head. 
Tentacular cirri long, slender, and grooved. Body having an anterior region of nine bristled 
segments, the fourth bearing in addition a large, tooth-like bristle with an oblique free surface. 
The middle region consists of only two elongated segments carrying foliaceous lamelle, 
which dorsally enclose capillary bristles. The posterior division has 130—140 segments, 
which are longer in front, shorter posteriorly, each bearing sub-cylindrical feet with bulbous 
