204 TEREBELLA. 
greater than the thickness, but in all other respects it corresponds gene- 
rally as well in configuration, as in propensities, with the others. 
The Spotted Terebella extends about an inch and half by less than 
a line in the largest diameter of the body ; and it is provided with 
twenty or twenty-two tentacula, stretching about an inch. The lower 
extremity terminates in points.—Plate XXVIII. fig. 10, enlarged. 
The definite branchize consist of a single pair, and are composed of 
six or eight subordinate forking ramifications. But we do not find either 
the number or arrangement of the forks corresponding exactly in different 
specimens. Indeed, I cannot affirm confidently, that in the species of 
Terebelle with three pair of branchiz, the formation of all the three strictly 
correspond. I rather think otherwise, though the extreme difficulty ob- 
structing observations prevents both description and delineation. In the 
finest specimens of the Terebella maculata the colour of the branchiz tends 
to scarlet, sometimes to tile-red, the central line of various intensity. Be- 
hind them stand a pair of short, obtuse, pellucid stumps, which are not 
distinguished by obvious peculiarities. The figure of the branchiz, how- 
ever, is quite distinctive, fig. 11, enlarged. 
The back of the tentacula is spotted brown ; their general appear- 
ance and functions may be compared to those already described ; but 
here a row of short obtuse teeth, somewhat apart, border each side of 
each tentaculum, such as have not been remarked in any of the others. 
These are best exposed, under favourable circumstances, on the organ 
being flattened. 
This is the most beautiful of the genus, mottled, patched, or speckled 
with variegated colours, wherein brown, green, and yellow predominate. 
A longitudinal light line traverses the speckled olive back ; the root of 
the pencils is bounded by a dark line, and a stripe within two darker 
lines runs down the belly. Faint-green stains the tentacula, their row 
of oblong or oval spots down the middle contracting or dilating along 
with their action. 
The Spotted Terebella constructs a very compact, small, cylindrical 
tube of minute grains of sand, which is prolonged by irregular curvatures. 
In the natural state, it is attached to corallines, or similar marine pro- 
