i6.6 



Stat. 35, 2 specimens. — Stat. 37, 3 specimens. — Stat. 81, 3 specimens. — Stat. 98, 1 

 specimen. -- Stat. 99, 2 specimens. — Stat. 109, 3 specimens. — Stat. 1 10, 1 specimen. — 

 Stat. lij', 1 specimen. -- Stat. 142, 1 specimen. -- Stat. 144, 2 specimens. -- Stat. 165, 

 1 specimen. -- Stat. 189% 3 specimens. — Stat. 213, 1 specimen. — Stat. 315, 2 specimens. 



This species is readily recognised when mixed with the other members of the genus, by 

 the following characters. The abdominal segments of the female are furnished with strong spines 

 and teeth. The right side of the last thoracic segment of the male is produced into a bifid 

 process. The males appear to be rather variable, both in the form of the right projection of 

 the last thoracic segment, and in the length of the thumb-like process on the first joint of the 

 exopodite of the right fifth foot. Two varieties of the male fifth pair are shewn in the report 

 on the Ceylon Copepoda. By a misprint it is stated in that report that the left side of the last 

 thoracic segment of Labidocera kroyeri var. gallensis has a trifid projection. It ought to read 

 right side of course. Only the typical form was obtained from the 'Siboga' plankton. 



Labidocera kroyeri has been recorded from the Indian and Pacific Oceans. It has also 

 been found in the Xorth Atlantic off the West of Ireland. 



4. Labidocera lacvidentata (Brady). Plate LI, figs. 1 — 10. 



Pontella laevidentata Brady, 1SS3, p. 93, pi. XXXVIII, figs. 1 — 6. 



Labidocera laevidentatum Giesbrecht, 1893, p. 446. 



Labidocera laevidentata Giesbrecht & Schmeil, 1898, p. 137. 



Labidocera laevidentata Wolfenden, 1905 (a), p. 1019, pi. XCVIII, figs. 20, 26, 27, 28, 38 (male). 



Labidocera kroyeri var. similis Wolfenden, 1905 («), p. 10 16, figs. 22, 23, 33 (female). 



This rare form was found in the plankton collected at the following two stations in the 

 area traversed by the 'Siboga'. 



Stat. 66, 75 females and 76 males. — Stat. 71, 1 male. 



Brady described the species from a single male specimen found in plankton collected 

 off Sibago Island, Philippines, on October 23rd, 1874. The species was not again met with 

 until Wolfenden recorded the male in 1905, from the plankton collected around the Maldives 

 by J- Stanley Gardiner. Wolfenden states that only the males are known, but the form he 

 describes as Labidocera kroyeri var. similis, is undoubtedly the female of Labidocera laevidentata. 

 The fifth pair of feet has not the slightest resemblance to the fifth pair of the female of 

 Labidocera kroyeri. 



The cephalothorax of the female is very similar to that of the male. The cephalic 

 segment is furnished with lateral hooks. Seen from above, the forehead is broadly angular in 

 outline. The side hooks are much nearer the frontal margin than in any of the other members 

 of this genus that have hooks (Plate LI, fig. 1). The last thoracic segment is symmetrical. 

 The posterio-lateral angles are produced into spines. The spines are rather divergent. The rami 

 of the rostrum are stout at the base, and are drawn out to a moderately fine point at the 

 apex. There does not appear to be any articulation between the rami and the basal part. The 

 excavation between the rami is wedge-shaped (Plate LI, fig. 3). 



166 



