EEPORT ON THE SCHIZOPODA. 69 



The caudal liml}s (PL XII. fig. 24) are powerfully developed iu both sexes, and repre- 

 sent true swimming organs. The basal part is somewhat adpressed and very muscular. 

 The terminal branches are shorter than the basal part, and exhibit the form of lanceolate 

 plates, fringed with strong natatory setaa. The inner plate (PI. XII. fig. 25) is rather 

 smaller than the outer, and exhibits, as in most Caridea, a slender secondary lobe attached 

 to the inner edge, and having at the tip a number of small curled spines (cincinnulag). 

 In the male, this branch on the two anterior pairs is peculiarly modified, to serve as 

 a copulatory organ (see PI. XL fig. 4). Especially on the first pair, this plate (PI. XII. 

 fig. 28 ; PI. XIII. figs. 3, 13 ; PI. XIV. fig. 7 ; PI. XV. fig. 22 ; PI. XVI. figs. 6, 14, 20) 

 presents a very complex structure, consisting of two principal portions, the outer 

 lamellar, and setiferous at the tip, and exhibiting on the posterior face a bounded pro- 

 jecting lobe, doubled over the plate ; whereas the inner juts out into several strongly 

 chitiuised processes of different forms, some assuming the shape of strong hooks or 

 pincers. This portion, too, is generally folded over the other in such a manner as to render 

 it a matter of some difficulty to spread out the whole plate in the same plane, with a view 

 of obtaining a correct idea of its structure. Of the two portions described above, the outer 

 only is found to correspond with the female plate, having likewise afiixed to it the 

 secondary lobe mentioned above, whereas the inner portion is quite peculiar to the male, 

 since it constitutes another enormously developed lobe, extending above the former 

 from the inner edge of the principal plate. Also on the second pair of caudal limbs, the 

 inner plate in the male (see PI. XII. fig. 29 ; PI. XIII. figs. 4, 14 ; PI. XIV. fig. 8 ; 

 PI. XV. figs. 2, 3 ; PI. XVI. figs. 7, 15, 21) exhibits a somewhat diverging appearance ; 

 but here it would seem that the secondary lobe itself, which is common to both sexes, 

 becomes peculiarly modified, since it juts out at the apex into several twisted lobules, 

 generally reaching more or less beyond the tip of the principal plate ; the cincinnulte 

 occur on a slight rounded prominence at the outer side of the lolje. As to the function 

 of these remarkable appendages in the male, there can, I think, be little doubt of their 

 serving to seize the spermatophores and place them on the sexual openings of the female. 

 The first pair are unquestionably most effective for this purpose, whilst the second pair 

 perhaps perform merely a coadjutory function. 



The telson (PL XII. fig. 27) in all the species of this genus, as well as iu the other 

 known Euphausiidse, exhibits a very similar appearance, being exceedingly slender and 

 tapering to an acute point. On the upj^er face two pairs of small denticles generaUy 

 occur, and on the lower face, at some distance from the apex, two very large spiniform appen- 

 dices are affixed in close proximity, slightly diverging and generally reaching far beyond 

 the tip of the telson. At the base of the telson, and likewise on the lower side, is seen 

 the anal opening, in the form of a longitudinal fissure. 



The uro^ioda (ibid.), too, only exhibit slight structural differences in the several 

 forms of the EuphausiidsB. The basal part is rather short and tliick, jutting out 



