26 
CLASS ANNELIDA. 
branching coeca, the extremities of which are fixed between 
the bases of the bundles of bristles, which serve as feet. 
M. Savigny distinguishes Halitheas, which have three 
tentacula, and between two of them one very small crest. 
They are destitute of jaw r s. 
We have one of these upon our coasts, which is one of the 
most beautiful of animals, in point of colour, Aplirodita acu - 
leata , L. Pall. Misc. v. ii. 1 — 13. It is oval, six or eight 
inches long, and two or three broad. The scales of its back 
are covered and concealed by a sort of stuff resembling tow, 
which arises from the sides. From these same sides spring- 
groups of strong spines, which partly pierce the tow, and 
bundles of flexuous bristles, shining with all the brilliancy of 
gold, and changing into all the tints of the rainbow. They 
do not yield in beauty to the plumage of the humming-bird, 
nor to the most lively lustre of precious stones. Lower down 
is a tubercle, from which spines in three groups issue forth, 
and of different dimensions, and, finally, a fleshy cone. Forty 
of these tubercles may be counted on each side, and between 
the first two are two small fleshy tentacula. There are fifteen 
pairs of broad scales, and sometimes inflated, on the back, 
and fifteen small branchial crests on each side. 
Some of these Halithea) have none of this tow-like stuff on 
the back, and our seas produce one species of them — Aplirod . 
Jiystrix , Sav. 
Another subdivision of the Aplirodita is that of Polynoe, 
Sav., Eu molpe, Oken, which have no tow on the back ; their 
tentacula are five in number, and their proboscis contains 
strong and corneous jaws. 
We have several species on our coasts. 
Aplirod. squamata , Pall. Misc. Zool. vii. 14. Littor. de la 
France, Annel. pi. i. f. 10 — 6 ; Polyn. Iccvis. Aud. and Edw. 
ib. pi. ii. f. 11 — 18; Aplirod . punctata , Mull. Vers, xiii ; 
Aplirod. cirrliosa , Pall. Misc. Zool. viii. 3—6; A. lepidota, 
