1912.] R. B. SeyMouR-SEWELL: Surface-Living Copepoda. 355 
in the 4th leg, in the latter the basipodite also presented at its 
distal external angle a short process carrying four teeth. Probably 
this abnormality was the result of some previous injury. 
Genus Canthocalanus, Scott. 
1. Canthocalanus pauper (Giesbrecht). 
Calanus pauper, Giesbrecht and Schmeil, Das Tierreich, Lief. 6, 
p. 16, 1808. 
Oceurrence’: Localities A, B, C,D;E,G,H, J, K,L, N, O, 
BAO: 
This species was almost invariably present all over the area of 
investigation, its maximum frequency of occurrence being obtained 
to the E. and S. E. of South Moscos South Island. 
In point of size it agrees very closely with the figures given 
by Giesbrecht and Schmeil (/oc. cit). 
In this species also a single specimen, again a female, possessed 
an abnormal 4th leg right side. The endopodite was normal but 
the exopodite was composed of only two segments: the distal 
segment was paddle-shaped and carried one external marginal 
spine and six setae, the proximai segment carried a single seta but 
no spine. 
2. Canthocalanus pauper (Giesbrecht) var. plumulosus, nov. 
Occurrence: Localities H, K, M. 
Seven specimens were obtained which presented, in varying 
degree, the plumose variation of the furcal setae. So far as I am 
aware the only previous record of this type of variation was given 
by Dr. Wolfenden, who found it in several closely allied species : in 
Undinula (Calanus) vulgaris, Paracalanus aculeatus and Calocalanus 
pavo bilaterally, and in Euchirella bella var. indica and Euchaeta 
novvegica' unilaterally, all his examples being obtained from 
the Maldive and Laccadive Archipelagoes. 
As he points out, the variation is extremely irregular, only 
two, of the seven specimens obtained, being identical ; the absence 
of feathering on the side branches of the plumose setae also agrees 
with his description of the variation as he found it in Undinula 
vulgaris. 
It would appear that this type of variation is extremely local 
in its occurrence, for as will be seen later, almost all specimens 
showing it were obtained in the region round the South Moscos 
South Island. 
! Dr. Wolfenden gives a figure of the variation in this species (the Fauna 
and Geography of the Maldive and Laccadive Archipelagoes, vol. ii, plate C, 
fig, 21), but I can find no mention of it in the text. 
