REPOET ON THE ANNELIDA. 
451 
which has three pairs of branchiae, Schmarda’s fig. d {loc. cit., p. 43) is a somewhat 
inaccurate but recognisable representation of the hook, hut his fig. d' probably refers to 
another species, it may be that with the three branchiae. 
The coarse sand in the intestine shows fragments of the spines of Echinoderms, 
minute Crustacea, sponge-spicules in great variety, and a few Foraminifera and 
Diatoms. 
Grube ^ mentions that the Terebella {Phyzelia) atricapilla, Ehrenberg, from the Red 
Sea, has from eighteen to twenty-two bristle-bundles and two pairs of branchiae, but this 
form diverges in other respects. 
The genus Scionopsis of VerrilD is either allied to this form or to Pista, but the 
absence of the minute characters renders its position at present doubtful. 
Pista, Malmgren. 
Pista sombreriana, n. sp. (PI. XXVIIa. fig. 27). 
Habitat — Dredged in 470 and 390 fathoms, off Sombrero and St. Thomas, West Indies. 
A fragment of the anterior region of a small Pista, having a diameter of about 2 mm. 
The tentacles and branchiae are absent. There are seventeen pairs of bristle-bundles of 
the ordinary structure, only the winged tips are proportionally longer than in Pista 
cristata. In the imperfect condition of the specimen the uncini alone can be relied 
on as distinctive. Each (PL XXVIIa. fig. 27) has a crown of three or four hooks 
above the great fang, the space beneath the latter differing decidedly from the same 
part m Pista cristata in its proportionally smaller size. The curves both above and 
below the anterior inferior projection are also characteristic. The entire outline, 
indeed, differs in minute detail, and the straight process is much larger than in the 
common form. 
The whitish sand in the alimentary canal contains the small circular spicular bodies 
formerly alluded to in other forms from the same site, sponge-spicules, and small 
Foraminifera. The most characteristic feature is the first mentioned. 
The great size of the oblique muscles and their contraction in the preparations cause 
the body-wall in section to assume the shape of a trefoil, the long dorsal arch exceeding 
the two lateral in size. The circular muscular coat is largely developed, and the dorsal 
longitudinal are also conspicuous by their massive proportions. The hiatus between the 
ventral longitudinal muscles is little more than the diameter of the large nerve-cords. 
1 Grube (Anneliclen des rothen Meeres), Monatsber. d. h. preuss. Akad. d. Wiss. Berlin, 1869, sep. Abd., p. 32. 
2 Report of the U.S. Commissioner of Fish, &c., 1874, p. 614. 
