178 Dr. Johnston's Contributions to the British Faund* 



3. Gam. dubius. 



Desc. Bodi) between two and three lines long, smooth, cor- 

 heous, when dead becoming yellowish-brown, marked across the 

 back with a few red lines. AntenncB rather more than onfe half 

 the length of the body, slender ; nearly equal, armed with very 

 short weak spines ; basilar joint of the superior longer than the 

 second or third, which indeed might with as great propriety be reck- 

 oned amongst the articulations of the last joint as distinct joints ; 

 basilar joint of the inferior shorter than the succeeding. Eyes 

 black, roundishj placed at the base of the antennae. Arms with 

 nearly equal hands, monodactyle, oblong, not much dilated, and 

 sparingly ciliated. They very much resemble those of the pre- 

 ceding species in their form, but are rather smaller in proportion 

 to the body. Legs spiny, spines not collected into fascicules, but 

 distributed along the whole member^ and both the short anterior 

 and long posterior legs are similar in this respect, monodactyle. 

 Natatory fms long, divided, and beautifully ciliated. Caudal 

 processes three pairs, long, with aciculate branches. Two rather 

 long conical spinous processes terminate the tail, and above these 

 are two much smaller papillae. 



Hab. Amongst confervae in pools left by the tide, not rare 

 near Berwick. 



Obs, I find from notes taken several years since, that I then 

 considered this species synonymous with the Pherusa fucicola of 

 Leach, but on a more attentive examination I am inclined to con- 

 sider them not only as distinct, but perhaps scarcely pertaining 

 to the same genus, if genera are to be established on such charac- 

 ters as that distinguished naturalist seems to think sufficient. In 

 the figure of the Fherusafucicola given in the Supplement to the 

 Encyclopaedia Britannica, the second joint of the superior antennae 

 is represented as elongated, the first pair of feet or arms filiform 

 -without any hand, and the hand of the second pair oval with a 

 very small claw. There is also a considerable difference about 

 the tail, the Pherusa having no terminal conical processes. Other 

 distinctions might be mentioned, but those already specified seem 

 of as high a value as many of those which divide the genera of 



