46 



much curved and terminating in four thick and short spines; the three other lobes are much 

 shorter, and each produced into an acute point. 



Length 15.5 mm. 



Female. — Rostrum and crest as in the male. (The antennulae mutilated, only the 

 first 'joint present). Coxae of third pair of legs (fig. 7) with the major part of the inner margin 

 convex and no tooth below or at the end, while the proximal inner corner is produced into a 

 protuberance about as in the species from Asia. The genital area (fig.' 7) is moderately short 

 but broad; the median part of its posterior margin, the transverse furrow, is strongly procurved, 

 while each sublateral part is produced backwards and very broadly rounded; the genital area 

 thus limited posteriorly is, seen from below, distinctly elevated, and its median part is longi- 

 tudinally a little concave, but no tubercles are observed. 



Remarks. — A. brasiliensis seems to be allied to A. americantis Ortmann, from the 

 estuary of the Amazon River. Both species agree in having only a single median tooth behind 

 the rostrum. Unfortunately Ortmann's figure of the copulatory organ is poor and small, and 

 of the clasping organ on the male antennuliE he has no figure or description, so that these 

 organs, which always afford good characters, cannot be compared with the features in A. brasi- 

 liensis. But two features remain which render it impossible to refer A. drasi/iaisis to the species 

 established by Ortmann. He has e.xamined specimens of both sexes and has not a word on 

 any sexual difference in the length of third joint of the antennulte, but in A. brasiliensis that 

 third joint is so strongly elongated in the male that he could not have overlooked this feature. 

 In Ortmann's fig. 27 the exopod of the uropod has the glabrous part of the outer margin some- 

 what more than twice as long as the ciliated part, and thus the ciliated part is proportionately 

 very much shorter in A. americamis Ortm. than in A. brasiliensis. 



8. Acetes paragnayensis n. sp. Figs. 8 — 14 in the text. 



The Copenhagen Museum possesses a large number of specimens collected by Dr. William 

 SoRENSEN in a lagoon at Rio Paraguay near its junction with Rio Parana. A single specimen 

 was taken by the same Zoologist in the outlet of Riacho del Oro in Rio de la Plata in feebly 

 brackish water. 



Male. — The rostrum (fig. 9) is acuminate, acute; the median crest has posteriorly a 

 strong tooth, and between this tooth and the end of rostrum is a rudimentary denticle or at 

 least an angular bend. Eyes rather large, nearly as in A. vulgaris. Antennulse (fig. 8) with 

 the peduncle nearly as in A. vulgaris^ as the third joint is slightly longer than in the female 

 and considerably less than half as long again as the inner margin of second joint; the thickened 

 part of the upper flagellum nearly as long as third peduncular joint. Lower flagellum (figs. 10 — 1 1) 

 has its shaft moderately short, 3-jointed; the main "branch" has its pro.ximal part curved some- 

 what upwards, the four proximal joints fused so that only the most distal of the articulations 

 is partly developed, with about 4 obtuse spines at the base on the lower side, while the third 

 joint has a very large protuberance downwards and outwards vertically on its joint, and this 

 protuberance is as deep as the diameter of the joint, almost- as deep as broad, somewhat 



