524 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



cephalothoracie legs (g, h, i) are all similar and of about the same size, 

 except the main branch of the first pair, (g,) which is much larger than 

 that of the others, but is still sack like and entirely without articula- 

 tions. The outer or exopodal branches of all the legs are slender, wholly 

 unarticulated, sack-like processes, while the inner or main (endopodal) 

 branches of the four posterior pairs are similar, but much stouter and 

 slightly longer processes arising from the same bases. The bases of all 

 the legs are marked with dendritic spots of red pigment like those upon 

 the lower margin of the carapax. 



The abdomen (m) is curved round beneath the cephalothorax, the 

 extremity extending between and considerably in front of the eyes. 

 The segments are scarcely distinguishable. The extremity, as seen from 

 beneath the embryo, is slightly expanded into a somewhat oval form, 

 and very deeply divided by a narrow sinus, rounded at the extremity. 

 The lobes into which the tail is thus divided are narrow, and somewhat 

 approach each other toward the extremities, where they are each armed 

 along the inner edge with six small obtuse teeth. 



The heart (I) is readily seen, while the embryo is alive, by its regular 

 pulsations. It appears as a slight enlargement in the dorsal vessel, 

 just under the posterior portion of the carapax. The intestine (lc) is 

 distinctly visible in the anterior portion of the abdomen as a well defined, 

 transparent tube, in which float little granular masses. This material 

 within the intestine is constantly oscillating back and forth as long as the 

 embryo is alive. 



The subsequent development of the embryo within the egg was not 

 observed. The following observations on the young larvae, after they 

 have left the eggs, have all been made upon specimens obtained in Vine- 

 yard Sound, or the adjacent waters, during July. These specimens were 

 mostly taken at the surface in the day-time, either with the towing or 

 hand net. They represent three quite different stages in the true larval 

 condition, besides a later stage approaching closely the adult. The 

 exact age of the larvae of the first stage was not ascertained, but was 

 probably only a few days, and they had, most likely, molted not more 

 than once. Between the third stage, here described, and the last, there 

 is probably an intermediate form wanting. 



First stage. — In this stage, (Plate IX, Figs. A, B, C, D,) the young are 

 free-swimming Schizopods about a third of an inch (7.8 td S.0 mm ) in 

 length, without abdominal appendages, and with six pairs of pediform 

 cephalothoracic appendages, each with the exopodus developed into 

 a powerful swimming organ. The general appearance is represented 

 in the figures. The eyes are bright blue ; the anterior portion and the 

 lower margin of the carapax and the bases of the legs are speckled with 

 orange; the lower margin, the whole of the penultimate, and the basal 

 portion of the ultimate segment of the abdomen, are brilliant reddish 

 orange. 



The antennula} (Fig. C.) are short and sack-like, with a single articu- 



