Maxilla. 



464 TA(;i': sKodsKi'iiic 



is in these forms considerably more strongly developed in the male and in addition differences 

 are to be observed in the proportions of the joints, in the development and equipment of the 

 bristles and in the basal spines, etc. This dimorphism seems presumably to be characteristic 

 of the genus as a whole. The fact that it has not been properly pointed out before is probably 

 due to the rather superficial nature of previous investigators' observations. It is certainly true 

 that Gr. S. Brady points out as early as 1868 b, p. 464, that the second joint on the exopodite 

 of the male second antenna is relatively longer than the corresponding joint in the female; 

 this statement is not found, however, in later works by this author. Of the other writers there 

 is only G. 0. Sars, 1887, jj. 20 who points out the existence of dimor})hism: ,,Idethele er 

 Svemmean tenner ne hos Hannen kjendelig kraftigere udviklede end hos Hunnen, skjondt, naar 

 undtages Bigrenen, af et temmelig overensstemmende Udseende"*. 



With regard to the endopodite of this antenna G. 0. Sars, 1887, p. 19 states that this 

 branch is characterized by two bristles in the female, one the comparatively long end bristle 

 and the other a short bristle situated distaUy on the second joint. In a few cases a similar short 

 bristle has also been observed by me on the second joint, as will be seen from the descriptions 

 of the species given below; the bristle in question is then attached at about the same place as 

 that where this joint of the male endopodite has three short bristles; it is presumably to be 

 considered as an abnormally appearing homologon to one of these bristles. There is no question 

 of any genus character. 



I might also point out in passing the abnormal type of the endopodite of the female 

 second antenna that is reproduced on fig. 10 of A. norvegica and whose resemblance to the male 

 endopodite during the second larval stage is striking. In this type, which has been observed, 

 as a matter of fact, in other forms within the Cypridiniformes, though only very seldom, we 

 perhaps have a proof of the homology of the distal bristle on the female end joint with the 

 proximal bristle on the same joint in the male. 



In all the species of this genus that were investigated by me the epipodial appendage 

 of the maxilla was of about the same relative size and type. In the genus description given by 

 me this organ has also been stated to be of about the same type and relative size throughout 

 the whole genus. All the reproductions of this organ that occur in the literature also show the 

 same size and type as was observed by me, with, however, one exception, G. W. Muller's 

 drawing, 1894, of A. teres, pi. 5, fig. 15. In this figure this organ is drawn consi- 

 derably smaller than I found it and its type is also somewhat different. I did not 

 make any reservation for this species in my general genus description because there seemed 

 to me to be strong reasons to believe that G. W. MtlLLER had made a mistake on this 

 point either by drawing incorrectly or by taking an abnormal specimen as a type for the 

 species. As will be seen from the remark under the species A. Miilleri described below, 

 one specimen of this species from the Gulf of Naples, determined by G. W. MCller as 

 A. teres, had a maxilla with an epipodial appendage of quite the same tyj)e as I found in 

 aU the other species of this genus. 



* On the wliulc Ihc iialaUiry aiilcniiac in Ihr male arc ()l>viously nioi'i' powrrrnlly ilrvcliqicil llian in Ihr IVrnali', 

 lh(iut>li. wiUi llir i'X(i'|ili(>n (iV till' rniin|iiiilili', llicy aKr'i'c I'airly well in a|i|)caiMiui'. 



