414 SPH^ROMID^. 



tail seen from above, whilst in the figure p is represented 

 the under surface of the tail, omitting the membranous 

 respiratory plates (pleopoda). 



Fully developed specimens above described were found 

 at Torbay by Mr. Griffiths, after whom it was named by 

 Dr. Leach; and the late Mr. W. Thompson found several 

 closely packed within the shell of a Balanus fixed on a 

 Modiola vulgaris in Belfast Bay ; some specimens in 

 the British Museum are from Lamlash Bay, in the Isle 

 of Arran. 



The smaller individuals, as we believe them to be, 

 which served Dr. Leach for his vaguely described Sph. 

 curtum, diifer only from the preceding in having the 

 tubercles of the terminal segment of the tail scarcely 

 elevated, and the body somewhat narrower. Dr. Leach 

 placed the species in his section " with the terminal seg- 

 ment of the abdomen having its extremity furnished 

 with two small notches," and having " the third seg- 

 ment of the abdomen widely notched posteriorly, whilst 

 the last segment is pointed at its tip." Professor Milne 

 Edwards is unable to comprehend this apparently contra- 

 dictory description. The fact is, however, that the wide 

 notch of the third segment of the tail is produced by the 

 two angular lateral incisions towards the sides of the 

 posterior margin of the confluent basal joints, whilst the 

 extremity of the tail itself is obtusely pointed, with a 

 notch on each side of the obtusely projecting extremity. 

 The upper surface of the terminal segment exhibits only 

 two very slight elevations, in the place of the rounded 

 tubercles of the larger variety above described. The 

 lateral appendages of the terminal segment of the tail 

 are comparatively small, and obliquely truncated. 



The smaller variety was first taken by Montagu on the 

 south-west coast of England. 



