Arthur. — On the Picton Herring. 209 



at posterior end, which reaches slightly beyond vertical line drawn from 

 anterior margin of orbit. Mandible projects a little beyond intermaxil- 

 lary. Mouth, when fully open, has a gape of three-quarters to an inch. 

 Opercula all well defined, posterior margin nearly vertical and straight, five 

 or six distinct strife on preoperculum pointing to base of pectoral fin. Dia- 

 meter of eye one-fifth length of head, pupil black, iris olive-yellow. This 

 organ — the eye — is sunk with orbit about one-eighth of an inch (or below 

 the plane of the cheek), and is protected by a beautifully-transparent disc 

 of apparently thickened skin, convex in form, extending half an inch 

 in front of centre of eye and three-tenths of an inch behind the same 

 point, and provided with a slit or opening directly over the centre of 

 eye vertical in position and gibbons in form or spindle-shaped. This 

 disc is evidently meant to protect the eye, and, at the same time, to 

 compensate for the diminution in the range of vision caused by the 

 eye being sunk in the head. Fins small and delicate in structure, rays 

 mostly soft or branched. One dorsal fin only, situated exactly midway 

 between snout and origin of middle or shortest rays in tail-fin, fourth 

 ray longest. Ventral fin origin, in vertical line from eighth or middle ray 

 of dorsal fin; tail-fin deeply forked, nearly bifurcate. The posterior end 

 of the anal fin is distinguished by a few long feathered rays much longer 

 than those adjoining them in body of fin. The scales are large, irregularly 

 rounded, transparent, and on exterior margin pectinate, also very tough, 

 and not deciduous. Along the base of or parallel to base of the dorsal, pec- 

 toral, and ventral fins, rows of scales are situated differing in form from the 

 body-scales of the fish, but resembling in shape those fins beside which they 

 grow ; and on each lobe of the caudal fin on both sides are scales or skin- 

 like plates, somewhat like the respective lobes they are attached to. The 

 other or body scales, besides possessing the shape described above, are 

 arranged in layers which overlap each other so as to leave a diamond pat- 

 tern over the surface of the trunk of the fish. As in the pilchard of the 

 English channel, described by Yarrell, a series of three-limbed scales, or 

 rather dermo-haemal plates or processes (for they are bony) exist along 

 the outline of abdomen from the pectoral to the anal fin. These are as 

 figured, are buried underneath the true scales, they diminish 

 in size towards the tail, overlap each other, and are placed 

 with short end of mid portion pointing towards the tail. 

 Looked at transversely they conform to the precise outline 

 of that part of the haemal arch here situated, viz., the bot- 

 tom. No lateral line visible on this specimen. In colour, 

 indigo blue on back and head, shading off into grey on sides, and silvery 

 white on belly, general aspect of body very silvery. There are seven or 

 14 



