ENTOMOSTRACA OF THE SCOTTISH NATIONAL ANTARCTIC EXPEDITION. 323 



Oithona minuta, T. Scott. 



1894, Uiflioua minuta, T. Scott, Trans. Linn. Soc, Ser. 2, "Zool.," vol. vi. p. 90, pi. ix. fig.s. 14-25. 



This somewhat rare form was observed in only a single plankton sample collected 

 at Station 66 in 7° 09' S., 34° 30' W.— that is, between two of the stations where 

 Cakmopia americana, Dahl, was obtained. The specimens from which the species was 

 described were obtained in Bananah Creek, at the mouth of the river Congo, and in 

 Loanda Harbour. 



Oithona similis, Claus. 



i86G, Oithona similis, Claus, Die Gupepoden fauna von Nizza, p. 14. 



1902, „ „ Giesb., Exped. Antard. Beige (1897-1899), "Copepoda," p. 28. 



The only stations where this species was met with were 102 and 116, in 36° 31' S., 

 51° 56' W., and 49° 35' S., 57° 40' W. respectively ; Station 116 was the last station 

 but one before reaching the Falkland Islands. Oithona similis was obtained in 

 many of the plankton samples collected by the s.Y. Belgica during its visit to the 

 Antarctic in 1897-1899. These samples were collected between lat. 69° 48' S. and 

 lat. 71° 24' S., and long. 81° 19' W. and long. 89° 12' W. The distribution of this 

 species is very extensive, and it is usually of more or less frequent occurrence all over 

 the North Sea, as well as in the North Atlantic. 



Fam. Cyclopid^. 



Genus Cydopina, Claus, 1863. 



Cyclopina helyicw, Giesbrecht. (PL I. figs. 2-13.) 

 1902, Cydopina helgicw, Giesb., ExpM. Antard. Behje, "Copep.," p. 3, pi. vii. figs. 1-15. 



A few specimens of a Oydopina that agrees generally with Ci/dopina helgicw, 

 Giesbrecht, were obtained in one of the gatherings collected by the Scotia in Scotia 

 Bay, South Orkneys, in June 1903 ; Station 325, 60° 43' 42" S., 44° 38' 33" W. 



In the female of this species, the antennules are composed of eighteen articulations ; 

 the first three joints are tolerably large, and do not difler greatly in size, but the 

 second is rather smaller than the one on either side ; the next three are very short, 

 more so than any of the others ; the seventh and eighth are larger ; the remaining 

 ten joints are small, but the last two are rather longer than those immediately 

 preceding (fig. 3). 



The end joint of the posterior antennae is provided with several geniculated setae 

 at its apex, and there are also one or two setse near the middle of the upper margin ; the 

 end joint is about twice as long as the third, while the third is rather longer than the 

 second (fig. 4). 



The mandibles have their masticatory edge truncated and armed with several 

 tolerably large teeth (fig. 5). 



The other mouth organs and the swimming feet do not diS'er very much from those 



(Roy. .sou. edin. trans., vol. xi.viii., 569.) 



