and Species of Crustacea. 315 



outer tail-plate being entire. From Alpheus it differs in the 

 equality and consimilaritjof the hands, and in the unshielded 

 condition of the eyes. . 



With Xika it agrees in the multiarticulate arras as well as 

 wrists of the second feet, and in several minute characters. 

 From Nika it differs in both the hands of the first feet being 

 didactyle, and in the outer tail-plate being entire. 



With Athanas it agrees in the unshielded eyes, and in 

 several other characters. From Athanas it differs in the inner 

 antenn£e having three filaments, and in the outer tail-plate 

 being entire. 



This elegantly shaped and brilliantly coloured little shrimp 

 was dredged by Arthur R. Hunt, Esq., F.G.S., in about 6 

 fathoms, off the Shag Kock*, at the northern end of Torbay, 

 on the 10th of August, 1877. During tliis summer I had en- 

 joyed the privilege of numerous dredgings in Torbay with him 

 in his convenient little yacht the ' Gannet ;' and we had both 

 lamented the paucity of results. On this particular day we 

 had been occupied at the south-west corner of the bay ; and 

 my friend, having landed me at Torquay with my opinia 

 spolia^ proceeded to the Shag Rock to spend another hour in 

 dredging alone. The result proved unwontedly rich. Besides 

 many examples of Comatula rosacea^ adult, and in the crinoid 

 condition variously advanced, and some other interesting 

 things, he obtained two creatures, which he at once saw to be 

 unfamiliar, and which proved to be, both of them, new to the 

 British fauna, and, as I believe, each of them a type of an 

 undescribed genus. The one was the elegant shrimp above 

 described ; the other was the nudibranch moUusk that forms 

 the subject of the following paper. Surely it was a most 

 noteworthy reversal of fortune that two new generic forms 

 should reward a sinsrle dred2:e-haul ! 



My friend, after he had preserved the specimens alive for a 

 few days in his own aquarium, kindly presented them both to 

 me. The Bellidia continued awhile in health and vigour, 

 manifesting, in its alternations of active motion and still repose, 

 a resemblance to the little Crangons. The liftings from vessel 

 to vessel, the confinement in small cells for microscopic ex- 

 amination, and the manipulations to which it was unavoidably 

 subjected in order to define and figure it, careful and tender 

 as 1 was in performing these, were, however, fatal to it ; for it 



* Mr. Hunt gives me the locality more exactly thus : — '• In about 

 fathoms on a submerged rock, off Meadfoot Sands, that extends from the 

 Shag Kock, in the direction of the Thatcher, to the well-known sunken 

 rock, Morris's Rogue." 



