230 Dr. Johnston on the British Nereides, 



papillary tentacula^ edentulous : tentacular cirri four on each 

 side, unequal : feet uniramous, bifid at the apex ; the dorsal 

 cirrus elongate, filiform, jointed ; the ventral one short : tail 

 with two filiform styles. 



Obs, This genus, which I have named in honour of the 

 daughter of Nereus and Doris, will take rank, as it appears to 

 me, between Scyllis and Hesione. It differs from the first in 

 the number and structure of the antennae, in the form of the 

 head, and in the arrangement of the eyes ; and from the latter 

 in the form of the body (which in this family is an important 

 character), and in the structure of the proboscis, which in He- 

 sione is very long and destitute of oral tentacula. 



1. Ps.fusca. Plate VII. fig. 4. 



Psamathe fusca, Johnston in Mag. Nat. Hist. ix. 15. Jig. 1. 

 Hab. The sea-shore within and between tide-marks. Berwick Bay oc- 

 casionally. 



Desc. Worm scolopendriform, about an inch in length, 

 slightly narrowed in front, tapered towards the tail, of a yel- 

 lowish-brown or fuscous colour, and in the paler specimens a 

 series of obscure spots may be observed down each side above 

 the feet. Head small, square, entire in front : eyes four*, 

 very distinct, occipital, placed in pairs : antennce four, shorty 

 biarticulate, frontal, the superior pair thicker and shorter than 

 the inferior : mouth furnished with a thick cylindrical joro^o^ci^, 

 whose aperture is encircled with a close fringe of papulous 

 tentacula : tentacular cirri four on each side, the inferior pairs 

 shortest, filiform, jointed, and issuing from a bulged base : 

 segments numerous, the anterior shorter and smaller than the 

 others, which are nearly of the same length and breadth : 

 feet much developed and prominent, all alike, conic, the apex 

 emarginate or divided into two obtuse lobes, between which 

 the bristles are protruded : superior cirrus elongate, filiform, 

 jointed like a Conferva, scarcely moniliform, and arising from 

 a swollen basilar joint : ventral cirrus short, not extending be- 

 yond the foot, neither is it jointed : bristles retractile, strong, 

 jointed near the top, the apical piece fixed on in a bayonet 

 fashion ; they are collected into two small but unequal fasci- 



* I have seen specimens in which there were only two eyes : from their 

 size a pair seemed to have coalesced. 



