42 



COPEPODA 



distinctly twice as long). The arrangement and number of setae are alike that of Macrocalanus, and 

 agree with Calanus by the presence of a single seta instead of two in segment 21. 



Antennae are in the main alike those of Calanus (cf. Wo If end en), but the Re II is by an 

 incomplete articular line divided into a proximal division, bearing two setae, and a shorter terminal one 

 with a single bristle. 



Mandibulae (figs. 3 a and c) cf. Wolfenden (taf. XXII fig. 5) have a well developed manducatory 

 portion with five distinct teeth and a few more or less fused. 



Maxillulae are alike Calanus finmarchiciis in most features, but differ by comparatively long 

 Re, and by the presence of 3 setae instead of 4 in Ri I (as seen in Wolfenden' s fig. 2). 



The Maxillae (fig. 3d) and Maxillipeds are as described by Wolfenden (taf. XXII figs. 4 

 and 6) in the main features alike those of Calanus, but the former organ has the fifth lobe comparatively 

 long with a thin hook, and the latter has the hairs, which cover the anterior surface of the Basp. Ill 

 proximally and medially bifurcate or divided into three branches, and the Se of Ri 4 — 5 are compara- 

 tively short and unarmed. 



The five pair of natatory legs have three segments in exopodites and endopodites; in basipod 

 III pes I a characteristic structure is found in the upwards directed hook, which dorsally in the concavity 

 has a rather irregular process, and ventrally bears the slightly plumous Si ; this hook is indicated in 

 most species of Calanus and in Macrocalanus as a small process on which the Si is placed (cf. Gi esbrech t 

 p. no). Pes II has the inner margin of second basipodite almost straight (cf. fig. 3 e). Thes pes III — IV 

 is in main features alike pes II, but Ri II with distinct Se. The pes V (fig. 3 h) is in general structure 

 like the preceding pairs, but is distinctly shorter; the inner margin of basp. has no hairs and no Si. 



Glandular pores, surrounded by prominent rings are observed in the pes II— IV, as shown in 

 fig. 3 e at the base of Se basp. Ill and Re I — III, and are observed surrounded by fine hairs distally 

 on the anterior surface of Ri III; the last mentioned pore and the pore corresponding to the wanting 

 Se 1 Re III are absent in pes V. 



Maculae cribrosae: In the legs and in a less degree in the other appendages small spots, 

 consisting of a more or less circular ring of minute pores, continued into a delicate threadlike glandular 

 duct? (fig. 3 f — g), are observed. 



As the arrangement of these, "maculae cribrosae" seems to be fairly regular, and as I have 

 only observed them in Megacalanus and Macrocalanus, I think they are of some systematic importance 

 and hope that the following account of their number is fairly exhaustive; they are often rather diffi- 

 cult to observe. The antennulae possess on the upper surface of the second segment a group of 9 

 pores; on the anterior surface of the Ri I of the antennae, at the base of the distal third, a group 

 of about 15 pores is observed. The manducatory part of the mandibulae bears at the base of the 

 serrations at least a single group, and the basp. Ill at least 2 rings of 7 pores anteriorly. The maxillulae 

 bear on the anterior surface a group of 14 pores at the base of L,e I and basally near the lateral 

 margin of Re. In the maxillae a single group of 12 pores is observed on the anterior surface of the 

 first basipodite and near the outer margin. 



On the posterior surface of the first pair of legs no pores are found; anteriorly a group of 10 

 pores is observed in basip. Ill medially to the articular cavity of Re I, and another one is seen in the 



