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 branchiae 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 

 Terebellsewith three pair of branchiae, 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 branchiae 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 branchiae, 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- 



