COPEPODA 



123 



each side of the median concavity, of a medial transverse row of about 25 more spine-shaped setae. 



The chitinous system of the oral surface of the labrum (fig. 2 a) shows as seen in figures (cf. 3 c) some 



similarity to that of E. citrticauda, but the arrangement of the groups of hairs in the longitudinal 



series is distinctly different, and is indeed very characteristic. The first group consists of about 30—40 



setae, placed in a single inwards convex row; the second group, which is perhaps fused with the lateral 



group, is represented by a big group of minute acicules; the third group consists of about 20 fairly 



long setae, and is converging towards the front; the fourth group, consisting of about 25 fairly strong 



setae, has the anterior portion placed almost transversely, and is almost fused with corresponding part of 



the other side; the fifth grottp, which consists of about 40 rather slender setae, is partly fused with the 



fourth; the sixth group is transverse, and consists of short delicate hairs. No transverse series of 



spinules is observed behind the median circular spot Nr. 3, 



and the two series behind the fourth median spot are fused 



to a square area, beset with spinules. 



The lamina labialis, as seen in fig. 2 b, is smooth and 



very insignificant; the arrangement of setae in front of lamina 



is, as seen in fig. 2 c, somewhat different from that of E. cur- 



ticauda. Behind the lamina 3—4 spinous areas are observed 



on each side. The series of hairs behind and upon the labial 



lobes show a rather regular arrangement, as seen in fig. 2 c, 



the medial posterior groups of a few hairs could not naturally 



be referred to any of the series. The first series consists of a 



number of short hairs, placed in a rounded area; the second Text-fig. 31. Euchirella messimnsis Claus. 



a— b (to the left), f ?. Ri pes II— III X 57- c. Pes 

 series consists of two rather independent almost transverse v dext; ridges of Re III x 175. d— e (in the 



rows; the third series seems onlv to be represented on the middle below ) ? d < st v > Ri P es n - m x 57- 



f. yd". Pes V ant. view X 57- 



labial lobes, and the fourth one has in addition to the regular 



row on the lobe a more medial and posterior portion; the fifth group, which consists of somewhat 

 stronger setae, falls naturally into a median portion which is fused with the corresponding part of the 

 other side, and a lateral one which is continued to the end of the labial lobe. 



o*. Size of specimen from Thor St. 183 5-46 mm.; anterior division 4-37 mm.; urosome 1-09 mm. 

 Giesbrecht's specimen measured 3-95 mm. 



The frontal keel is distinctly higher than figured by Giesbrecht (Taf. 36 fig. 25). The oral ap- 

 pendages are practically like Giesbrecht's description, but the mandibulae possess as in Euch. 

 rostrata a well developed manducatory portion; the labrum and labium show a similar development 

 as in this species. 



According to Giesbrecht (p. 240) the only difference between the natatory legs in males and 

 females is found in the completely smooth inner margin of the fourth pair of legs in the males; in 

 my specimens, however, the difference is even better marked than in E. rostrata and curticattda (PI. 

 VIII fig. 1). The articulation between Re I and II pes I is indicated, but the Se Re I is wanting; 

 the Se Re II is quite rudimentary; the pore in the outer margin of Re II is well developed, but 



that of Re III seems to be wanting: The St. of the Re III pes II has about 50 instead of c. 25 teeth. 



16* 



