NERKIS. [59 
1U1t, {S)LPAL@) 
It has been very judiciously observed, that this is a genus but im- 
perfectly known ; and certainly its characters are very imperfectly speci- 
fied. Nor is this surprising, for, of two species to be found in Scotland, 
one is extremely rare, and the other so minute as most readily to escape 
observation. These may be inserted in the genus, with a few observa- 
tions, which I offer diffidently. 
§ 1. Spo serrcornis.—Plate XX. Fig. 22. 
Length nine lines. Body somewhat angular, composed of segments 
tapering downwards, and terminating in three processes, somewhat ellip- 
tical. Head bearing two large, strong, active, extensile, and flexible long 
tentacula. Two black specks, or clusters of specks, like eyes, in front. 
Colour universally pale dingy yellow. 
This creature constructs a long irregular tube of shelly fragments, 
or other indurated substances, lined with a tough silky matter. The par- 
ticles that may be selected for the edifices are seized and passed along the 
tentaculum, and apparently carried to the mouth. Then they are ap- 
plied in such a manner as to contract the orifice of the tube, as if to ob- 
struct access. The tube itself is expeditiously constructed. 
The animal lies constantly within its dwelling, its long tentacula. 
equalling half the extent of the body, sweeping around. 
Having had only a single specimen, which occurred many years ago 
at Queensferry, I am induced to suppress various other observations, 
although the animal survived nine months, as no subsequent opportunity 
presented itself admitting their corroboration. 
This creature seems to be identified with that of Baster, Opuscula 
Subseciva, tom. ii. Pl. XII. fig. 2. Likewise the Polydore, found by 
Bose on the coast of Carolina, as shewn in his Hist. Nat. des Vers., t. i. 
Pl. V. fig. 7, is nearly allied to it. 
PLATE XX. 
Fic. 22. Spio seticornis. 
