NEREIS. 159 



II. SPIO. 



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. SPIO SETICORNIS. 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, torn. ii. PI. XII. fig. 2. Likewise the Polydore, found by 

 Bosc on the coast of Carolina, as shewn in his Hist. Nat. des Vers., t. i. 

 PI. V. fig. 7, is nearly allied to it. 



PLATE XX. 



FIG. 22. Spio wticornis. 



