Gatty Marine Laboratory, St. Andrews. LS IL 
has about six strong spines with tapered tips supporting the 
setigerous lobe, which bears a series of translucent yellowish 
bristles which have a slight curvature at the tip and diminish 
a little towards the pseudo-articulation. The tip varies in 
length, and ends in a bifid hook with a pair of pointed 
wings, which spring from the sides where the tip begins to 
be differentiated. These bristles are also found on the 
2nd and 8rd feet; but on the 4th, where the first 
branchial process is, they are replaced by simple bristles 
with winged tips. The secondary spur below the terminal 
hook is often very slender and appears to be readily abraded, 
since many show no trace of it. 
In the example from the ‘ Porcupine’ the bristles of the 
first four feet (that is, one more than in the Neapolitan) 
have a similar outline, but the bifid tip has its secondary 
process more distinct. In this, as in the Neapolitan form, 
the developing bristles show the respective differentiations 
as clearly as those fully formed, the tip being the first part 
to appear. The spines supporting the setigerous region are 
fewer, viz. about four. The simple winged bristles which 
supplant the foregoing special bristles appear in the 5th 
foot, which bears the first branchial stem. 
At the 10th foot of the Neapolitan form the bristles are 
stout, have tapering tips with narrow wings finely serrated 
at the edges, the central region being striated. The brush- 
shaped forms have slender shafts and about seven rather 
broad teeth distally. The spines pass to the front of the 
foot; the bristles are superior and in two groups, which 
diverge slightly from each other—with the cirriform lamella 
beneath—in the centre. In the example from the ‘ Porcu- 
pine’ the spines are fewer, the bristles proportionally more 
slender, but also with narrow serrated wings, and the tips 
of the brush-shaped forms are longer and narrower, and 
the six or seven teeth appear to be more slender. In this 
form, moreover, the great inferior hooks begin about the 
12th foot, whereas in the Neapolitan they do not appear 
till the 14th or 15th. In contrasting the hooks of the 
20th foot, both have an upper more elongated and an in- 
ferior broader and stouter kind; but those of the ‘ Porcu- 
pine’ form are considerably broader and shorter than in the 
Neapolitan. In the latter, both bristles and hooks extend 
to the posterior end of the body, three of the latter often 
occurring in a foot. 
The gill in full development (Pl. X. fig. 2) forms a 
slender tapering pyramid with whorls of short pinnules from 
base to apex, and with two large blood-vessels, which also are 
Q? 
