152 



COPEPODA 



The rostrum is strong and directed downwards. The head is, in contrast to Farran's fig. 4, 

 well separated from the first thoracic tergite. The fifth somite is well developed and bears a short, 

 downwards directed hooked spine (text-fig. 42). The abdomen differs from that of the preceding species 

 by being less hairy. The antennulae extend to the end of the chephalosome; the mouth appendages 

 are scarcely different from those of Ch. notacantha. In the structure of the natatory legs scarcely any 

 difference was observed between this and the preceding species. The third foot is shown in text-fig. 

 42 e. The only difference between male and female is found in the presence of a fifth pair of legs in 

 the former sex; this pair of legs (text-fig. 42 g) is in most respects like that of the preceding species, but 

 differs by the equal length of the two exopodites as well as in a few minor points. 



In the structure of the labrum and its surroundings no difference of great interest was observed 



between this species and the 

 preceding ones (cf. PI. VI figs 

 1 a— b). 



Y^ (St. IV). Size of male 

 from Thor St. 183 was 3-46 mm. ; 

 anterior division 2 - 8i mm.; uro- 

 some 0-65 mm. 



The body is more slender, 

 and so is the rostrum; the 

 lateral corners are somewhat 

 more robust (text-fig. 43 f). The 

 abdomen consists of three seg- 

 ments as shown in text-fig. 

 43 f. The mouth appendages 

 show the usual differences. The 

 exopodite of the first pair of 

 legs shows no trace of segmentation, but has three well developed Se. The endopodite of the second 

 pair of legs is unsegmented, and the two last segments of the exopodite are fused, bearing 3 Se and a 

 single glandular pore at the base of Se 3. The inner margin of the second basipodite of the fourth 

 pair of legs is smooth. The only difference between the male and female is found in the fifth pair of 

 legs, which, as shown in text-fig. 43 h, is less developed than in the preceding stage. 



f c?. Size of male from Thor St. 183 was 5-28 mm.; anterior division 4-15 mm.; urosome 1-3 mm. 



The rostrum (text-fig. 43 a) is somewhat shorter, and the lateral spines of the end of the thorax, 



which are placed less dorsally, are more slender and extend a little beyond the hinder margin; the 



fifth thoracic tergite is not distinctly marked out. The abdomen (text-fig. 43 b) is scarcely different from 



that of Ch. notacantha. 



The antennulae extend beyond the end of first abdominal somite. The two basal segments of 

 the exopodites are well separated in the antennae, and the maxillae have the setae of the first lobes 

 somewhat contorted, and the Sp. of the lob. V more swollen at the base, but in other respects the 

 mouth-limbs were like those of the male of Ch. notacantha. 



Fig. 42. Ch. parvisphia Farr. Yd 1 (St. V). 

 a. L,eft lateral corner X 29. b. Third basipodite of mandibula X 5°. 

 X 33- d. Pes II Re III; glandular pore X 57- e. Pes III sin. X 29. 

 basipodite of pes IV. g. Pes V in ant. view X 33- 



c. Pes II 

 f. Second 







