Dr. Johnston on the British Aphroditacea. 433 



Desc. Body generally about one, rarely two inches long, 

 depressed, linear-oblong, of equal breadth at both ends, of a 

 uniform cinereous colour, rough : scales twelve on each side, 

 rather large, ovate, imbricate, rough, with brown granulations, 

 ciliated on the external margin, the overlapped smoother than 

 the exposed portion, for the granules on the former are more 

 minute than on the latter ; the anterior scales are smaller and 

 rounder than the others and completely cover the head, which 

 is a subtriangular pink or purplish corneous plate, furnished 

 with four small eyes : antennce three, the central one largest, 

 bulbous near the point : palpi two, longer than the antennae, 

 swollen near the apex ; the tentacular cirri similar to the su- 

 perior cirri of the feet ; these are white with a blackish ring 

 at the bulb where the acumination commences, retractile, ori- 

 ginating from above the dorsal branch of every alternate foot 

 and under the scales ; the three last pairs of feet each with a 

 cirrus: feet twenty-five pairs, obtuse, subbifid, the dorsal 

 branch shorter and less than the ventral, each terminated with 

 a brush of stiff brown bristles, and under the ventral branch 

 there is a small setaceous cirrus and also a fleshy spine at its 

 junction with the belly : bristles when removed golden yellow, 

 those of the dorsal branch slenderest, gently curved, acutely 

 pointed, and serrulate for about half their length ; those of the 

 ventral branch stouter, slightly bent near the top, and serru- 

 lated with a double series of teeth on the outer side of the 

 bend ; each tufl of bristles inclosing a dark brown straight 

 spine, the inferior stouter than the upper one : ventral surface 

 straw-colour, prismatic, marked with the viscera, and some- 

 times spotted with black near the base of the feet. 



This species differs remarkably from those which follow in 

 the tenacity with which the dorsal scales adhere to their tu- 

 bercles of attachment, from which they cannot be separated 

 except by the dissecting knife ; and this fact determines the 

 species to be almost certainly the Aphrodita squamata of 

 Linnaeus. His Aph. scabra must ever remain in uncertainty, 

 for no Polynoe has twenty scales, as he states them to be in 

 that species. The Aph. scabra of Otho Fabricius is said to 

 have fifteen pairs of scales ; and overlooking this important 

 fact, I, on a former occasion, much too confidently identified 



Ann. Nat. Hist. Vol. 2. No. 12. Feb. 1839. 2 g 



