PAREXOGONE HEBES. 447 
with excellent figures. He describes the buccal cavity, the pharynx, proventriculus, ventri- 
culus and post-ventriculus, the latter resembling the intestine in its ciliated epithelium, 
but differing in having unicellular glands. He shows that, contrary to the view of Hisig, 
the muscular tissue of the radial columns in the proventriculus is striated. The fine lines 
on the organ correspond to the annular bands of non-striated muscular fibres; the dots, 
which are often coloured in life, are the outer ends of the cores of the radial columns of 
striated muscle. There is a dorsal and a ventral raphe. Posteriorly the organ has two 
grooves, with a ridge of thickened epithelium between the plates of opposite sides. 
PAREXOGONE HEBES, Webster and Benedict, 1887; var. HIBERNICA, Southern, 1914. Plate 
CXXXYV, fig. 2—bristle ; 2a—spine. 
Specific Characters—Head separated from the palpi and buccal segments by faint 
erooves, and the length exceeds the width. Three tentacles, a long, subulate median, and 
two small lateral, which are about one-fifth as long as the median. Three pairs of eyes 
outside the lateral tentacles, and they vary in size ; exterior to them are conspicuous, ciliated 
nuchal organs. Palpi large and fused dorsally, a shallow groove between them ventrally. 
Brain elongated and bilobed. Buccal segment as large as the head, bearing a pair of small 
bulbous tentacles with stiff cia at the tip. The body is about 7 mm. long, with thirty-one 
bristled segments, somewhat fusiform, creamy white in colour, without other pigment. The 
proboscis extends from the second to the fifth bristled segment, is covered with dark pigment, 
except a narrow strip in the fourth segment. Anterior part of proventriculus long and 
narrow, with twenty rows of points, the succeeding portion being muscular and non-glandular, 
with two small ciliated sacs. The proboscis has ten soft papillze anteriorly and a conical 
tooth. Colour grey or flesh-colour, eyes dark red or black. 
SYNONYMS. 
1887. Pedophylax hebes, Webster and Benedict, U.S. Com. F. and F., p. 716, pl. ii, figs. 31—36. 
1914. Haogone » var. hibernica, Southern. Proc. Roy. Irish Acad., vol. xxxi, No. 47, p. 17. 
1918. Parewogone ,, Caullery and Mesnil. Bull. Soc. Zool. France, xlu, p. 127, 5 figs. 
1921. 3, » McIntosh. Ann. Nat. Hist., ser. 9, vol. vii, p. 300. 
Habitat—Blacksod, Galway and Clew Bays, Lough Swilly and the coast of Kerry, 
both between tide-marks, and dredged in 78 fms. (Southern). It is partial to a bottom of 
sand and shells. 
Distribution. — Provincetown, Mass.; Eastport, Maine (Webster and Benedict). Caullery 
and Mesnil found it living in compact sand on the shores of France. 
A minute but typical Syllid, the feet armed with bristles of moderate leneth. The 
body is tapered more posteriorly than anteriorly, ending in a sharply conical tail. The 
foot has an unequally bilobed setigerous process, the dorsal portion with the spine (Plate 
OXXXV, fig. 2a) being the smaller and having a rounded papilla near the tip. Dorsal cirrus 
small and bulbous, with stiff cilia distally. Bristles in a fan-shaped series. Shafts curved, 
swollen and bevelled at the tip: terminal pieces coarsely spinous proximally, and some 
distance below the tip is a broad tooth (Plate CXXXV, fig. 2). A single spine is present, 
