176 Dr. Johnston's Contributions to the British Fauna, 



the precision of a Monograph, to enable any one conversant with 

 the subject, to determine, whether the objects I present him are 

 already familiar to naturalists or not. 



Class. Crustacea 



Order. Heterobuanchi 



Sect. Ampiiipoda 



Gen. Gammarus 



NCHIA. / 



Lamarck. 



1. Gam. maculatus. 



Desc. Body six lines long, smooth, glossy ; back dusky with 

 a faint yellow band across each segment, and a row of yellow 

 spots along each side, most conspicuous on the posterior half of 

 the body; sides lighter-coloured, faintly marked with yellow. 

 Antennce transparent, unspotted, ciliated with long hairs ; superior 

 longest ; basilar joint shorter than the second or third. The seta 

 is one half the length of the last joint. Eyes large, oblong, run- 

 ning backwards, and having the appearance rather of a blotch of 

 a fine red colour than of eyes. Arms alike, with oval dilated mono- 

 dactyle hands, hairy, particularly on their inner margin. Legs 

 white, monodactyle, armed with bristles. 



Ilab, Sea coast near Berwick, rare. 



Obs. The specimen from which the above description was 

 taken, was found amongst some corallines dredged from deep 

 water. It belongs to Leach's restricted genus Gammarus^ of 

 ■which he has described four species. Three of these are well 

 known to me. His G» aquaticus is common ht're, as every where 

 else, in our wells and ditches ; the C, locusta swarms in the 

 pools left on the recess of the tide ; and the G. marinus^ remark- 

 able by its strongly ridged back, is frequently taken here, in 

 great abundance, in the baskets used for catching crabs. Our 

 animal is quite distinct from any of these, nor can it be the 

 G. Camylops^ which I have not seen, for that is characterized 

 by having " flexuous eyes," a character not in the least applicable 

 to our 6r. maculatus. 



