122 



COPEPODA 



are not mentioned in Giesbrecht's rather short description. The species is probably identical with 

 Wolfendens var. atlantica, as the differences set forth viz: "head separated from first thoracic segment", 

 basipodite II of pes IV, which has "only six rather broad-based and long spines", and the smaller size 

 (3-8 mm.) are not of much importance. It is more doubtful, if it is identical with E. atlantica Wolf., in 

 which the abdomen is only */$ of the anterior division in length. Most probably the described male 

 belongs to this species, especially on account of the characteristic articular membranes of the thoracic 

 tergites, the frontal keel, the almost absolete rostrum and the knob-like process of the second basipodite 

 of the maxillipeds. The arrangement of secretory pores and the structure of Se of Ri I in the legs are 

 like those of the females. Some of the differences are certainly due to sex, f. inst. longer abdomen, 

 longer endopodite of antennae with greater number of setae; a few of the other differences are not 

 quite the same as those found in related species, but it must be remembered that sexual differences 

 are apt to vary from the one species to the other. 



33. Euchirella messinensis Claus. 

 (PI. IV figs 2 a— c; PI. VIII fig. 1; text-figs 31 a— f.) 



1863. Undina messinensis n. sp. Claus, p. 187, pi. XXXI. 

 1892. Euchirella messinensis Claus. Giesbrecht, p. 232, taf. 15 



& 3 6. 



1894. Nee. 



1896. 



1898. 



1903. 

 1903. 



Th. Scott, pp. 45 — 46. 



Canu, p. 424. 



Giesbrecht & Schmeil, 



P- 3i- 

 Giesbrecht, p. 201. 

 Thompson & Scott, p. 244. 



1904 

 i9°5 

 i9°5 

 1908 

 1909 

 1909 

 1912 

 1911 



Euchirella messinensis Claus. Cleve, p. 190. 



Esterly, p. 151, fig. 18. 

 G. O. Sars, p. 4. 

 Farran, p. 37. 

 Pesta, p. 23. 

 A. Scott, p. 56. 

 Pesta, p. 13. 

 Wolf en den, p. 237. 



Description. f$. Size of specimens from Thor St. 183 57 mm.; anterior division 4-5 mm.; uro- 

 some i-2 mm. Giesbrecht's specimens measured 475 mm. 



The sac-shaped protuberance of the genital somite, which is rather variable in the specimens 

 examined, differs somewhat in shape from Giesbrecht's fig. 18 (Taf. 36); it is distinctly widened out 

 towards the end, does not reach much behind the end of the third somite and beyond a distinct con- 

 cavity at the right side the tip is directed towards the right; the protuberance is dorsally excavated. 

 The Ri of the antennae possesses 5 setae in Le and 3 (not 4) in Li. The first pair of legs has the outer 

 margin between the Se of Re I — II almost straight with a distinct pore, continued into a conical 

 process at least in one specimen. The glandular pore in the outer margin of Re III pes I is placed r / 3 

 of the length of Re III measured from the base. The number of glandular pores is as in E. rostrata; 

 in the Re I exteriorly distinctly removed from the tip a transverse split (secretory pore) was observed 

 not only is pes II but also in pes III — IV, in which the real pore is found; a similar one was observed 

 in Basp. Ill medially to the insertion of Se I, and in Re III near to the insertion of Si 4. 



Somewhat behind the insertion of the antennulae a well marked elevation is found, which is 

 well separated ^from the labrum proper by an anteriorly convex chitinous line; in connection with 

 the mentioned elevation as well as with a transverse chitinous bar behind the mouth a strong 

 chitinous system forming a covering for the manducatory part of the mandibulae is found. The an- 

 terior surface of the labrum does not possess any setae in front of the marginal row; this consists, on 







