440 Dr. Johnston on the British Aphroditacece. 



Desc. Body seven or eight inches long, linear, flattened, 

 slightly tapered towards the tail, the anterior extremity obtuse 

 and somewhat rounded, the beak covered with two rows of 

 scales of an ash or sometimes reddish-brown colour, but as 

 some of the scales are often paler or whitish, the body then 

 appears piebald : head small, convex, corneous, concealed by 

 the rounded anterior pair of scales, terminated in front with 

 three short setaceous two-jointed antennae, the central one 

 larger and longer than the others : eyes none, but at the base 

 of the least antennae there are two depressed punctures very 

 like eyes : palpi two, setaceous, half an inch long, arising above 

 and at the sides of the mouth : mouth inferior, furnished with 

 a retractile cartilaginous proboscis about an inch long, armed 

 with two pairs of sharp horny teeth plain on the margin, the 

 aperture encircled with a double series of papillary tentacula, 

 the outer series much longer than the inner, which however 

 is the most numerous : scales imbricate, kidney-shaped, con- 

 vex, roughish, the concealed portion pale, the outer and larger 

 margin fringed with very delicate hairs and some short ano- 

 malous processes ; there are about 140 scales on each side, 

 each affixed to a fleshy tubercle, from the end of which a ten- 

 tacular filament is extended, equal to the feet in number, and 

 placed exactly above them : feet extremely numerous, obtuse, 

 bifid, the superior branch papillary with a brush of long un- 

 equal bristles curved upwards, the inferior branch truncate, 

 somewhat sinuate, with two brushes of short bristles, and un- 

 derneath with a setaceous cirrus equal to the superior : bristles 

 of superior branch, setaceous, unjointed, serrulate on their 

 upper half, with a spine in the centre of the brush ; the 

 bristles of the inferior branch are most of them stout, enlarged 

 near the top, and terminated with a sort of claw toothed on 

 the inner side ; some of these are marked with a few circular 

 striae below the joint, and there is a spine in their centre ; 

 there are other more slender bristles which are two-jointed, 

 the apical joint longish, acute, and smooth : ventral surface 

 pale, perlaceous, marked down the middle with a red vessel : 

 tail terminated with two short filaments. When killed in fresh- 

 water the scales readily drop off*, and the relaxed body of a 

 large specimen will then measure ten or twelve inches. Young 



