288 MGIVM. 



the other sex a smaller specimen (ij inch long), having 

 the two basal joints of the upper antennas not dispro- 

 portionably enlarged, and the last large segment of the 

 tail emarginate- truncate, with a shallow furrow down the 

 centre, and two obtuse raised keels at its sides. In other 

 respects no difference appeared to exist. Except that 

 the eyes in the figure of this smaller individual are 

 represented as being of the same size as in the larger 

 ones (uniting in the centre of the forehead), we should 

 have referred it to Dr. Leach's jfiga bicarinata, or more 

 probably to dB. tridens, with the central tooth of the tail 

 plate worn away (the eyes being large, as in that species). 

 Dr. Johnston, however, regarded it as belonging to the 

 same species as the larger individuals, and probably the 

 male of it, considering the dilatation of the basal joints 

 of the upper antennae as a sexual character, or one de- 

 pendent on age (and of insufficient value, therefore, to 

 be ranked among the characters which are seized upon 

 to divide tribes and families from each other), and also 

 that the conformation of the terminal segment of the 

 tail is not sufficient to discriminate species, as Dr. Leach 

 seems to have believed, " for his specific characters em- 

 brace no other part," at least in the species of JRga. 

 Unfortunately the comparative rarity of these parasites 

 does not yet allow us to determine this point. 



The individual of this species described by our late 

 friend Dr. George Johnston was taken in Berwick Bay 

 on a cod-fish, and is preserved in the British Museum, 

 which al&o contains another specimen from the Northum- 

 berland coast, presented by Mr. R. House. 



There are also British specimens of unnoticed locality in 

 the Hopeian collection ; and we have received them from 

 Shetland, from the Rev. A. M. Norman, who also records 

 it from the Moray Frith. 



