HETEROMASTUS FILIFORMIS. 493 
Famity HALELMINTHID. 
NOTOMASTUS RUBICUNDUS, Kefersteon, 1862. Plate CX X XVI, fig. 16—anterior hook. 
Specific Characters —The cephalic region is conical, with four larger eye-specks and two 
groups of smaller eyes in front, a lobulated nuchal organ on each side. Body 10 em. long 
and 2 mm. broad, vermiform, slightly enlarged anteriorly about the sixth segment, tapered 
posteriorly, and ending in a button-shaped tail, all with neural parapodia, and dorsal para- 
podial gills (Hisig). Genital opening at the fifth pair, and two in the sixth. Thorax reddish, 
abdomen brownish or yellowish-green, or bluish-green posteriorly. Bristles simple winged, 
tapering, eleven pairs. Abdominal hooks with four teeth im lateral view, from the 
thirteenth segment backward. Mature from December till May. 
SYNONYMS, 
1862. Capitella rubicunda, Keferstein. Zeitschr. f. wiss. Zool., Bd: xii, p. 123, Taf. xi, figs. 7—18. 
1864. Notomastus Benedeni, Claparéde. Glanures, p. 54, pl. iv, fig. 9. 
1868. Capitella rubicunda, idem. Annel. Neap., p. 27. 
» ? Notomastus lineatus, idem. Ibid., p. 278, pl. xxvii, fie. 4. 
1887. Capitella rubicunda, Hisig. Capitell., p. 863, Taf. xxxv, figs. 17 and 23; Taf. xxxv, fig. 20; 
Alani, seatb, ier, 4g UMent, i, ayer, IL @ 
1915. Notomastus rubicundus, Allen. Journ. M. B. A., vol. x, p. 637. 
1922. - . McIntosh. Ann. Nat. Hist., ser. 9, vol. ix, p. 24. 
Habitat.—In fine clean sand off the Yealm Estuary, Plymouth (Allen). 
This was considered to be the young of N. latericeus, but Allen says its habits differ, 
H. rubicundus never protruding its proboscis. 
Distribution —St. Vaast-la-Hougue (Keferstein) ; Port Vendres (Claparéde) ; Mediter- 
ranean (Hisig). 
An anterior hook is drawn in Plate CXX XVI, fig. 16. 
Keferstein, who discovered this species at St. Vaast-la-Hougue, gives a detailed 
description of its structure. The body measures 250 mm., and is divided into an anterior 
and a posterior region, the latter commencing at the twelfth bristled segment. The hook- 
rows are short dorsally, long ventrally in the posterior region. There are two pairs of 
cephalic ganglia, and the great nerve-cords have neural canals. The alimentary canal has a 
papillose proboscis, cesophagus, oval stomach and a gut which terminates on the last 
segment, the anus having a short ventral lobe. The segmental organs occur in every segment, 
and probably open between the dorsal and ventral feet, though he found another pore on 
each side behind it. He did not notice the sexual apertures with the hooks, his example 
being a female. Hxternally was a parasitic Loxosoma. 
HETEROMASTUS FILIFORMIS, Claparede, 1868. 
Specific Characters.—The cephalic region agrees with that of the type (Claparéde), and 
so with the proboscis, which has clavate papille. ‘The body reaches the length of 6 cm., 
