COPEPODA 



55 



fairly long setae, slightly convex inwards and posteriorly, are found. The median circular spots and 

 transverse series of hairs were not observed. The lamina labialis shows three serrations, of which 

 the median is the smallest. The scrrula 6-dentata is found as usually; the arrangement of the setae 

 was not examined in detail. 



i$. About the description of the mature males I refer to Sars and Giesbrecht. Size: 07 

 — I -02 mm. 



Y$— J" (St. V). Size: c? o-8o mm. (O.Exp. 1900); ? (o-6i -j- o-i8) = 079 mm. (Ingolf 96 Cyl. 45). 

 The shape of the bod)- is in the main like that of the mature female, but the head and the first 

 thoracic somite are fairly well separated, 

 and there is an indication of limitation 

 between fourth and fifth thoracic somite. 

 The first abdominal somite is, at least in 

 most specimens, distinctly produced below 

 (text-fig. 12 b). The oral appendages are 

 scarcely different from those of the mature 

 females; the natatory legs, however, show a 

 few differences; a very short Se Re II is 

 present in the first pair of legs. The ex- 

 terior margin of the last segment of exo- 

 podite is smooth in the fourth pair of legs, 

 but, as usual, dentated in the third pair. 

 The fifth pair of legs appears more clumsy 

 with shorter terminal spine. 



The male differs from the female 

 by the less prominent first abdominal somite, and by the better developed asymmetrical fourth pair 

 of legs (cf. Canu) (textfigs. 12 c — d). 



Y$— c? (St. IV). Size: (0-48 -{- 0-14) = 0-62 mm. This stage is easily distinguished from the pre- 

 ceding one by the number of abdominal somites (3 only). As in the other stage, differences are found 

 in the less prominent fifth pair of legs in the males (cf. text-figs. 12 e — f). 



Of the copepodites (stages I — III) I am not sure of having observed any; according to Ob erg 

 these as well as the larval forms are rather difficult to distinguish from those of Fsetidocalamis elon- 

 gatus] they are, however, smaller and more clumsy, and have the exopodite and the endopodites of the 

 antennae of almost equal length. From Ingolf St. 62 (Apst. 14) I have examined a young specimen 

 (St II) 0-6 mm. long and one (St. I) 0-48 mm. long, which on account of the long endopodite of the 

 antenna perhaps ought to be referred to this species. 



Variation. In a single mature female? (F. 389 0. Exp. 1900), the size of which was (o-68 -f 0-2) 

 = 0-88 mm. the left leg of the fifth pair consisted of four segments as in the immature male, while the 

 right consisted of two segments only. A somewhat smaller female from the same locality had both pair 

 of usual structure. Bay has taken 3 specimens with the left leg somewhat longer than the right. 



Text-fig. 12. Paracalanus parvus Claus. 



a. f9 Genital somite in lateral view X 90- 



b. yQ (Stage V). Abdomen X 90. 



c. yo" (Stage V). Abdomen X 90. 



d. j'c? pes V in anterior view X c. 400. 

 e— f. y9— o' (Stage IV). .\bdomen X 90. 



g. f Q. Abnormal specimen with well developed pes V X 9°. 



