328 ASELLID^E. 



terior angles. The last segment is almost triangular ; the 

 apex being directed posteriorly, two small styles arise 

 from each side of the apex." 



[We have copied Mr. Goodsir's figure of the tail at z, 

 which shows that there is only one pair of caudal styles, 

 and not two pairs, as his description would lead us to 

 infer.] " All the external margins of both of these 

 segments are thickly fringed with minute hairs and 

 spines. The branchiae are almost semicircular, and each 

 of them is armed on its internal edge with a small 

 appendage. The external plate of the branchiae is 

 extremely narrow, and is not composed of two equi- 

 lateral pieces, as in the other Asellida, but consists of 

 one piece only, with an immovable suture in its mesial 

 line. It is attached to the body by its base only." 



This species was found by the late Mr. H. Goodsir in 

 the Frith of Forth. It is quick and active in its move- 

 ments, running among the branches of coralline with 

 great rapidity. Mr. Goodsir never observed it swim- 

 ming, its legs being, indeed, unfitted for that kind of 

 locomotion ; when pursued along the bottom, it runs 

 quickly, but often stops suddenly, turns round, and 

 assails its annoyer. We have received it from Mr. 

 Robertson, who took it at Kames Bay, and from the 

 Rev. A. M. Norman, who found it at Cullercoats and 

 Seaham. 



