studies on marine Oslracods 737 



Distribution: — Atlantic and Antarctic Oceans between lat. 18" X. and lat. 58" S. 

 Indian Ocean. 



The „A n t a r c t i c" specimens were consequently cauglit within the area of distri- 

 bution stated bv G. W. MtlLLER. 



Genus Euconchoecia G. W. Muller. 



Euconchueciu, G. W . .\ILLLK1{, 1890 a etc.; this name is also used in the following works: 

 U. S. Brady, 1902 a, P. T. Cleve, 1905, Th. Scott, 1909 and 1912 a, V. VAvha, 1906. Halo- 

 cypris (part.), Til. ScoTT, 1894 and Paraconchoecia (on account of a mistake in the determination), 

 P. T. Cli:\k, 1900. 



Description: — Shell: — The rostrum is well developed. The ,,unsymmetrical 

 glands" have their exit symmetrically on the posterior margin of the shell near the posterior 

 dorsal corner; they are sometimes rather small. Apart from these there are no large groups 

 of glandular cells at all. The pores of the surface are small and difficult to verify with 

 certainty. The part of the selvage that runs on the rostrum has no spines. 



F'rst antenna: — This shows marked dimorphism. 



Male: — This is moderately long and powerful; it grows gently narrower distally. 

 It has five joints, but the boundary between the third and fourth joints is often rather difficult 

 to ascertain with certainty. The proportion between the lengths of the joints seems to be subject 

 to rather slight variation in the species so far known; I may give as an example the result of 

 measurements made by me on E. Chierchiae: 



1:11 :III :IV : V :- about n : t : ' : T = I ■ 



The second and third joints have no bristles at all. The fourth joint has numerous bristles 

 ventrally (from close on twenty to a considerably larger number); these are developed as thin- 

 walled sensorial filaments. All these bristles are of the same type, moderately long and all of 

 about the same length, moderately thick or rather narrow, of about equal thickness throughout 

 their whole length, rounded distally, almost straight and bare. The end joint has four- or five 

 bristles, all without spines. Two of these bristles are rather powerful and long, of different 

 lengths, the longest being rather considerably longer than this antenna, the other about half or 

 three-quarters of the length of the former one, both rather strongly and evenly bent ventrally. 

 The two or three remaining bristles on this joint are moderately long or rather short and rather 

 weak, straight or irregularly bent. 



Female: — This is rather considerably shorter and weaker than that of the male, 

 with a comparatively weakly developed muscular system (cf. p. 580 above) and with rather 

 indistinct division into joints. The number of joints seems to vary; according to wliat has been 

 stated it seems that in most cases only three joints can be distinguished, but sometimes, liowever. 



Kooloc. bUlraK. Uppiul.i. Suppl -lid. I. V^ 



