50 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [344] 
of the twenty-fourth body-segment an appendage develops below the 
lower fascicles of set, and farther back becomes broad, foliaceous, and 
divided into several lobes; back of the twenty-eighth segment the 
branchiz appear in a row on each side of the back, and soon become 
long and ligulate; at the same time other ligulate appendages develop 
from the upper lateral appendages, which become dorsal, and these, 
with the gills, form four rows of processes along the back, outside of 
which are the elongated setz and other appendages. The posterior 
part of the body is more slender and much more delicate than the an- 
terior part, and so fragile that an entire specimen can rarely be obtained, 
and those that are obtained, when in confinement very soon detach 
fragment after fragment, until only the anterior part is left. In their 
natural habitations they would undoubtedly be able to reproduce their 
lost parts, like many other annelids. The color of this worm is ocher- 
- yellow, tinged with orange, or dark orange ; there are usually two rows 
of dark-brown spots along the back ; the branchie are blood-red; and 
posteriorly there is a brownish red median dorsal line. The proboscis 
is very singular, for it is divided into several long, flat, digitate pro- 
cesses, separate nearly to the base, and somewhat enlarged at the end. 
Another species of this genus, of smaller size, A. fragile V., often oc- 
curs in the sandy flats in great numbers, its small holes sometimes com- 
pletely filling the sand over considerable areas and extending nearly 
up to half-tide mark. This species grows to the length of four inches 
or more, with a diameter of about .10. Its head is even more acute 
than in the last species, with a very slender, translucent apex. The 
body has the same form, but is more slender. The processes above and 
below the fascicles of setze begin to appear at the fourteenth segment, 
and the sete begin to be decidedly elongated at the fifteenth. The 
dorsal branchiz begin on the sixteenth segment, and become long and 
ligulate at the twentieth. The coloris yellowish orange to orange-brown ; 
the dorsal surface, posteriorly, and the branchiw are red. The body 
posteriorly is very slender and extremely fragile. The last or caudal 
segment is smooth, oblong, with two long filiform cirri at the end. The 
proboscis is large and broad, consisting of numerous, often convoluted, 
lobes or folds, united by a thinner membrane or broad web. 
The Aricia ornata V. is another related species, living in similar 
places with the last and having similar habits. The head is acute in 
this species, but the dorsal branchiz and lateral appendages com- 
mence much nearer the head, and the side appendages are developed 
into crest-like, transverse series of papillae, which cover the lateral and 
ventral surfaces of the body anteriorly. 
Two species of Spio also occur in similar situations inhabiting small 
round tubes or holes made in the sand near low-water, often occuring 
in great numbers in certain spots. They prefer localities that are not 
exposed to the full force of the storms. One of these, S.setosa V. (Plate 
XIV, fig. 77,) is remarkable for the length of the seta in the dorsal 
