252 BRANCHIOMMA VESICULOSUM. 
an increasing prominence, and the posterior papilla is considerably larger. Hach arises 
from a broad base, and is somewhat flattened, since the vertical exceeds the transverse 
diameter, and the distal end has three parts, viz. the posterior process or papilla (not to be 
confounded with either a dorsal or a ventral cirrus), which springs from the middle posteriorly, 
and two areas for the bristles. The papilla is short and nearly cylindrical in the preparations, 
and is directed backward. The upper bristles (Plate CX XVIII, fig. 4a) arise from a curved 
area above a papilla, so that the long axis of the row is antero-posterior, and the convexity 
of the tip with the wings is turned outward and their points directed backward. They have 
long shafts and finely tapered, slightly curved tips, with narrow wings. The inferior row 
of bristles again has its long axis vertical, and the bristles have shorter and stouter striated 
shafts (Plate CX XVIII, fig. 4c), shorter tips and broader wings. The tip in all is finely 
pointed. 
The bristles of the second region are arranged like the inferior group in front, viz. with 
the long diameter of the row vertical, and they spring from the tip m a double row—that is, 
on each side of a ridge of tissue. The wings of these are intermediate in character, being 
narrower than the lower series and wider than the upper series of the first region. Their 
tips, however, are long and finely attenuate, especially the upper forms. The chief changes 
in the bristles toward the tip of the tail are the shortening of the shafts and the great elonga- 
tion of the tips, which stretch from each side of the flattened body as finely tapered hairs 
(Plate CX XVIII, fig. 46). A distinct curvature occurs at the commencement of the wings. 
The anterior rows of hooks occupy the summit of the rounded ridge, which begins close to 
the setigerous process and passes ventrally near the scute. Hach hook (Plate CX XVIII, 
fig. 4e) is avicular in shape, with a marked forward curvature of the posterior outline at the 
crown, a powerful and sharp main fang with a series of very minute serrations above it, 
a neck of moderate length and a long tapering base. Bold strive pass from the crown to the 
base, into which they curve a little behind the prow. Hach hook is accompanied by a short, 
broad bristle with a spatulate tip bent at an angle, and ending in a point, or when seen 
obliquely the tip is hastate or on edge hook-like. In a specimen from South Devon, 
in the British Museum, both these and the hooks had their ““ heads” tinted brown. The 
posterior hooks (Plate CX XVIII, fig 4) are smaller, with a shorter neck and shorter base, 
and more distinct serrations above the main fang. 
Neural canals occur from the second setigerous segment backward. The modified seg- 
mental organs are found in the first, second and third setigerous segments, and they open 
by a common canal on the dorsum. Brunotte describes those of the ordinary type in the 
posterior region, and he limits the anterior pair to two segments. 
Reproduction.—Lo Bianco (1909) finds the period of sexual maturity to be from August 
to October at Naples, where it is termed “ Fiucchetielle d’arena.” The young examples 
of 8—20 mm. progress with the tail in front. The number of the branchiz varies from 
fourteen to sixteen. The first two have an eye always larger then the others. The first 
thoracic segment is less completely fused with the buccal than in the adult, and shows two 
reddish ocular specks placed at the base of the branchia on each side. The first thoracic 
segment bears the otocysts and their otoliths. The bristles of the region are more spatulate 
than in the adult. The anal segment ventrally is in two lobes separated by the “ copra- 
gogue,” whilst on the dorsal surface are four to eight ocular specks which disappear in the 
