310 iS. I. /Smith — Early Stages of Hippo talpoida. 



The ocular peduncles are stout, regularly tapering to near the 

 bases, and are usually carried perpendicular to the mesial plain, though 

 they admit of considerable motion in all directions. The cornea is 

 considerably larger than the diameter of the peduncle, its diameter 

 being nearly a third of the horizontal diameter of the carapax, and, 

 when the peduncle is held straight out, reaches slightly beyond the 

 lateral margin of the carapax. 



The antennulae (Plate XL VI, tig. 1) are still rudimentary, simple, 

 sackdike, unarticulated appendages, tapering towai-d the tip, which is 

 furnished, as usual in this stage of development, with three stout, 

 filiform, obtuse setne, diftering slightly in length, diameter, and amount 

 of curvature, and of which the longest is about half the length of 

 tlie antennula itself. 



The antennse (Plate XLVI, tig. 2) are of about the same length as 

 the antennula-, but of nearly the same diameter throughout, and are 

 armed distally, at the outer edge, with an acute, dentiform process 

 (a, fig. 2) directed straight forward and itself armed with a minute, 

 setiform spine on the inner edge near the tip. Between the base of 

 this process and a slight, rounded prominence (c, fig. 2), situated at 

 the extremity of the inner margin, and which represents the rudiment- 

 ary flagellum, there is a similar, but slightly more slender, process 

 (b) attached at its base by an oblique articulation and armed, near 

 the tip, with a minute, setiform spine like that upon the outer process. 



The oral appendages differ very little from their condition in the 

 last zoea-stage, under which they are fully described. The labrum 

 and labium differ scarcely at all, except in size, in the three zoea- 

 stages here described. The labrum, as seen from beneath, is a broad, 

 somewhat triangular prominence between the bases of the antennulae 

 and the tips of the mandibles. The labium is deeply bilobed, though 

 far less deeply than in the adult, with the lobes broadly rounded and 

 the entire margin clothed with microscopic hairs. 



The mandibles are nearly as in the last zoea-stage. They are stout 

 at the bases, but taper to very slender tips, which are only slightly 

 different on the right and left side. There is no molar area, but the 

 crown of the mandible is longest in a vertical direction and is armed 

 inferiorly with four long, but blunt, teeth which decrease rapidly in 

 size as they approach the middle of the crown, where they are met 

 by a series of six or seven long, slender, setadike processes which 

 occupy the superior half of the coronal margin. 



The first pair of maxilhie (Plate XLVI, fig. 11) are symmetrical 

 and composed of the same parts as in the adult. The inner lobe 



