19I2.} R. B. SEYMOUR-SEWELL: Surface-Living Copepoda. 373 
the 18th segment is also smaller than in P. securifer. With regard 
to these last two points, it would appear not improbable that they 
may be merely a variety, and as I shall show in the next species, 
a considerable degree of variation is met with in specimens of 
undoubtedly the same species. 
In the few specimens that I obtained the relative lengths of 
the two limbs of the knee-joint were 47: 43, thus agreeing with 
Wolfenden’s measurements of his supposed P. spinifes o. 
The only difference that would appear to be constant between 
Wolfenden’s P. spinipes 7 and P. securifer @ is the absence of 
the large triangular tooth on the proximal limb of the claw of the 
5th leg. JI have, therefore, come to the conclusion that he was in 
reality dealing with a variation, either local or seasonal, of Pontella 
securtfer. 
6. Pontella spinipes, Giesbrecht. 
Pl. xxiv, figs. I—4. 
Occurrence:-Localities A; C, Dy EO. 
A considerable number of typical females were obtained in 
the above localities and associated with them were several males 
that I believe to be the true male of this species. 
@ In these specimens the total length is 3°15—3°5 mm. The 
head is furnished with side hooks and the rostral lens is large and 
well-developed. 
The last thoracic segment and abdomen are like P. securifer. 
The length of the abdomen and furca is contained nearly 34 times 
in that of the cephalo-thorax. 
Ist antennae. The left antenna very closely resembles that 
of the female, the proportionate lengths of the segments in the 
two sexes are given below :— 
g 
Wee 2 set Ae eae Gee On 1O, BI 2) B34 U4 DoahO le lo. 191205 21. 2223024), 
FLONT elle Lon LOwsn LA 7a 2 See FOm ake 4. ln 37014 42) 40m 340) 304 30223. 25. 
od 
I. 2. 
3 
50. 37. 9: 
ASM, Gin Wa Oy MIO ANG TOS MOS iz By Mpeg SUS Ch AO iin Os ee. 
75 TOs LEak War by L3alA Th Ga Lieven 22.12 Ge 3509 240.45. 31-5. 32. 390252 25. 
In both sexes the 11th and 12th segments are partially fused 
together. 
In general appearance the grasping antenna very closely 
resembles that of P. securifer; there are slight differences in the 
toothed plate of the 18th segment, which is shorter apparently 
than in P. securifey and has fewer teeth; the teeth are long and 
sharp and set fairly widely apart, diminishing gradually in size 
towards the distal end. ‘The number present varies from 25 to 30. 
