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290 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 
series. Guiesbrecht, in his beautiful monograph, “ Pela- 
gische Copepoden, Fauna and Flora des Golfes von Néapel,”’ 
gives twenty species besides a number of undetermined 
forms. A reference to his Pl. LI. will show the slight 
divergence of character which separates many of the 
species, and I found it no easy task always to determine 
to which species a particular specimen belonged. Some, 
indeed, seemed to vary from any described form, but not 
sufficiently so, in my opinion, to constitute a specific dif- 
ference, and I am inclined to think that a more systematic 
study of the genus might result in grouping together, as 
one species, some now classed separately, rather than in 
an increase of their number. 
The species before us, Coryceus ovalis, well illustrates 
my meaning. There seems to me no sufficient reason for 
separating C. ovalis, C. robustus, and C. obtusus into 
separate species. In general appearance they are re- 
markably alike in all particulars, the supposed difference 
being a slight relative variation in the length of a par- 
ticular segment, or a variation in a bristle, or in the 
inclination of the caudal stylets. The representative 
species, C. ovalis, was present in 9, 10, 20, 22, 23 Wyse 
collection and in No. 9 Herdman collection, taken in the 
Indian Ocean and the Mediterranean, the former being an 
addition to the known range of any of the three species of 
Coryce@us referred to. 
Coryceus venustus, Dana. 
1852. Coryceus venustus, Dana, U.S. Expl. Exped., p. 1222, 
Pl. LXXXVL, figs. 4, a—d. 
The chief point of difference between this species and 
the last is the length as compared with the breadth of the 
last abdominal segment. In C. ovalis that segment is 
about twice as broad as long, the conditions being reversed 
in C. venustus. It was present in 5, 6, 8, 11, 13, 14, 17, 18, 
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2 i. 
