COPEPODA 



39 



and the Se I — III of Re III, and, surrounded by a number of fine hairs, somewhat removed from tip, 

 on the anterior surface of Ri III; in addition to these the pes III — V have a pore at the base of Se 

 Re I, and so has pes V, in which, however, only 2 pores are observed in Re III. 



The number as well as the arrangement of the "maculae cribrosae", of which none was 

 observed in the mouth-appendages, is less regular than in Megacalanus. On the anterior surface of 

 Re I, at base of Se, the organ was observed in pes II — III, but not in pes IV. On the posterior surface 

 the maculae were sometimes found near the base of Se Re I pes II, and regularly in pes II as well as 

 pes III near the base of Se Re II and Se I — II Re III; in pes IV only a single group was observed 

 in Re II. 



On the anterior surface of pes II — III, medially to insertion of the Re, a group of delicate fila- 

 ments, projecting through minute pores (?) and perhaps corresponding to a macula cribrosa, was found. 



The lateral outline shows, somewhat in front of the lab rum, a low rather elongated elevation. 

 In the middle, as well as on each side, well removed from the hinder margin, a group of fairly long 

 and slender, delicate hairs are observed. The posterior margin has a median incision, and well removed 

 from the middle on each side a transverse marginal row consisting of about 15 short lancet-shaped 

 spines (fig. 2 a). On the oral surface the usual longitudinal series is dissolved into 5 more or less trans- 

 versely placed groups, as shown in fig. 2 a pi. I; the bristles of the more posterior groups are more 

 slender and longer than those of the anterior ones; between the group (Nr. 4) on each side and behind 

 the fourth central spot a transverse row of granules is found. 



The lamina labialis has 1 median and on each side 2 lateral teeth; in front of this we 

 have an exterior and mostly anteriorly slightly convex series of rather long bristles and an interior short 

 one of shorter bristles (pi. I fig. 2b). The serrula 6-dentata has the 4 posterior spines club-haped; 

 between these and the labial lobes scarcely any setae were observed. The area labialis has behind the 

 labial lobe a median somewhat convex group, and a lateral oblique group of numerous hairs on each 

 side; the labial lobes bear about 8 groups of shorter and longer hairs, which seem to be arranged in 

 3 series. 



Y (St. V). Size: 8*4 -\- 2 - 2 = io - 6 mm. The shape of body is scarcely different from that of the 

 f$ except for the urosome, which has four somites, hardly produced beneath, of which the second 

 is almost twice as long as the first, which is the shortest. The antenunlae extend only 4 segments 

 beyond the end of the furca; the measurements differ in minor points only; the maxillulae have in 

 one specimen only a single seta in the basp. Ill in another 2 as in f£. The Re has only 10 setae. 

 In other respects no difference was observed. 



Y (St. III). Size 6'i — 6-3 mm. (no -f- °'53)- 



Of this stage I have examined 2 specimens; in spite of the different shape of the head and 

 the short antennulae I do not doubt that the animals are rightly referred to this species, as they agree 

 with it in several important features e. g. the curious structure of the maxillulae. 



The body in much more slender, and the head shows no trace of a frontal keel; the first as well 

 as the fifth thoracic tergite is well marked. The urosome consists of 2 somites, of which the second 

 is almost twice as long as the rostrum as well as the furcal branch. The antennulae, which just 

 reach beyond the end of the abdomen with the tip of the last segment, consist of 23 segments; the 



