EXPEDITION ANTARCTIQUE BELGE 



II. - The Order MYSIDACEA 



The collection contains two species. Both were new when handed over to me, but 

 one of them has been described by E. W. L. Holt & W. M. Tattersall in their « Preliminary 

 Notice of the Schizopoda collected by H. M. S. Discovery in the Antarctic Région (Ann. 

 Mag. Nat. Hist., ser. 7, vol. XVII, 1906), and in the same paper the authors mention and 

 name the other species, but do not describe it. Both species hâve received the names proposed 

 by me ; when Mr. Holt in io,o5 visited Copenhagen I showed him the figures inserted in 

 this paper and a number of spécimens of both species secured by the Swedish antarctic Expé- 

 dition, and with his usual courtes) 7 he accepted the names already chosen by me, viz. Pseudomma 

 Bclgicœ and Mysis maxima. A short time after Prof. H. Coutière worked out and published 

 his report on the Decapoda and Schizopoda from Dr. F. Charcot's antarctic Expédition ; he 

 described and gave twenty figures of Mysis maxima, and established a new genus, Antarctomysis, 

 for its réception. Fortunately the figures of this form drawn by me before Coutière's report 

 was published will, I hope, be a useful supplément to the représentation given by the able 

 French author. 



1. — Pseudomma Belgicae (Hansen, MSS.), Holt & Tatt. 



(PL II, figs. 2 a— 2 c) 

 1906. Pseudomma Belgica Holt & Tattersall, Ann. Mag. Nat. Hist.. ser. 7. vol. XVII, p. S. 



From the Belgica only a single immature female is to hand, measuring 16. 5 mm. from 

 the front margin of the ocular plate to the tip of telson ; the figures are drawn from this spéci- 

 men. But from the Swedish antarctic Expédition I hâve a very large number of spécimens, and 

 in the following I take them somewhat into considération, but the figures illustrating some 

 variation must be postponed to the report on the Swedish Expédition. 



The species is closely allied to P. roseum G. O. S., P. affine G. O. S. and P. Sursit YVilL- 

 Suhm; the main différences are found in the eye-plates, the antennal squama and the telson. 

 The eye-plates are completely coalesced, slightly cleft in front, forming a somewhat subqua- 

 drangular laterallv rounded plate which is less or more depressed at the médian Une, and the 

 portion at each side of this longitudinal excavation is frequently raised towards the front margin 

 where it in this case is produced in a feeble or very conspicuous angular protubérance; the 

 margin of the eye-plates is otherwise completely smooth, without vestige of any serration. The 

 antennal squama three and a half to nearly four times as long as broad ; its rounded apex 

 extends slightly or at most a little beyond the tip of the marginal spine which is well developed. 

 The telson is sometimes not far from twice as long as broad (fig. 2 b), frequently somewhat 

 shorter and broader at the base ; its end is broadly rounded with three pairs or rather often 

 only with two pairs of long spines (') and a pair of feathery setae ; each latéral margin has 

 sometimes five, frequently six, seven or eight spines. 



I 1 1 Holt & Tattersall say that the apex has four pairs of spines, but I never found more than three pairs 

 of long terminal spines, while a fourth pair of considerably shorter spines are inserted at the end of the latéral 

 margin (corap. fig. 2 c). 



