414 SPHEROMIDZ. 
tail seen from above, whilst in the figure Pp 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 SpA. 
curtum, differ 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. 
