24 



G. O. SA&S. 



[No. 1. 



far more fully developed, constituting a large elongate plate, the 

 inferior, more or less expanded extremity of which reaches far 

 bey ond the tip of the endopodite. This plate is moreover produced 

 above, on the outer side of the epipodite, to a lamellar prolonga- 

 tion, ascending up the sides of the body and expanded at the 

 end to a more or less broad rounded lamella, bordered by 

 a number of finely ciliated bristles. One of these bristles becomes 

 successively very elongated on the legs that succeed the anterior 

 pair (see Pl. V, fig. 1), and on the middle pairs of legs it is trans- 

 formed into a flexible cirrus (fig. 2 c), projecting far beyond the 

 dorsal surface of the trunk within the incubatory cavity. These 

 cirrus-like appendages, the number of which would seem to be 

 somewhat variable, serve for keeping in place the eggs deposited 

 within the incubatory cavity, their ends being often found firmly 

 adhering to the chorion of the ova (see Pl. VI, figs. 1, 2). The 

 whole outer edge and apex of the exopodite is bordered by a 

 series of strong setæ, those issuing from the apex being the 

 longest and rather densely crowded; also at the inner edgeoccur 

 a number of setæ, here however somewhat shorter and farther 

 apart. All the setæ of the legs are distinctly biarticulate and 

 finely ciliate on both edges. 



In comparing the several pairs of legs with each other, we find, 

 besides the unequal size, also some minor differences in structure. 

 Thus, the first pair of legs (Pl. IV, figs. 7, 8) are highly dis- 

 tinguished by a peculiar lamellar expansion proceeding from the 

 anterior surface of the endopodite, immediately below the epipodite, 

 and not found on any of the other legs. This expansion has the 

 form of a rounded vertical lamella, extending anteriorly and 

 bordered by a number of very strong curved setæ, which form 

 a spreading fan partly encompassing at the sides the end of the 

 labrum, when applied against the oral parts. Moreover, the 

 inferior part of the exopodite in this pair is very slender and 

 elongate, almost linear, with the extremity not in the least ex- 

 panded. On the posterior pairs the exopodite-plate becomes 

 successively shorter and broader, with the upper prolongation 

 less produced and forming at last merely a small linguiform 



