334 iS. I. Smith— Early Stages of Hlppa talpoida. 



Three of the specimens, found upon the beach and preserved at tliis 

 time, prove interesting as they apparently represent a stage next 

 succeeding the raegah^ps. In these specimens the carapax is a little 

 over 4'"'" in length and the whole integument is of a much firmer 

 consistency than in the megalops-stage. The cephalo-thoracic 

 appendages have all advanced slightly toward the fully mature form. 

 The ocular peduncles have increased in length hut are more slender, 

 the diameter at the tips being apparently, absolutely very slightly 

 less than in the megalops-stage. In the antennula; (Plate XL VIII, 

 fig. 2), the distal prominence upon the under side of the second 

 segment of the peduncle, projects as far as tlie distal end of the third 

 segment and is more densely fringed with setae than before. The 

 flagellum has increased only slightly in length and has three or four 

 additional segments, but the secondary flagellum is a third as loug as 

 the primary and is composed of four segments, of which the ultimate 

 is as long as the penultiiuate and antepenultimate together. The 

 oral appendages and thoracic legs have changed comparatively little, 

 although the slender posterior pair of thoracic; legs are much more 

 completely armed with sette and spinules than before. 



The first segment of the abdomen has become pretty firmly con- 

 solidated with the cfirapax, tliough the suture marking the union is 

 still conspicuous and much deeper than in tlie adiilt. The expansions 

 on the sides of tlie second segment are a little broader longitudinally, 

 and the tip and the antero-lateral angles of the telson are more acute 

 than in the megalops. The most marked change, however, has taken 

 place in the appendages of the anterior segments. In all three of the 

 specimens examined, there are no appendages whatever upon either 

 one of the five anterior segments. The sudden and total disappear- 

 ance of these appendages raises the question, wlicther the ovigerous 

 appendages of the female are derived directly from the swimming 

 legs of the megalops, or are developed specially, at a later period. 

 It is of course very difticult, if not impossible, to distinguish the 

 sexes, at so early a period, by any of the primary sexual characters ; 

 so that the three specimens examined may very likely all be 

 young males ; in which ease the early disappearance of the append- 

 ages might, naturally enough, be expected, as there are no append- 

 ages on any of the five anterior segments in the adults of that sex. I 

 have, however, examined several additional specimens of the young, 

 in which the carapax was less than 7""" in length, without, in any 

 case, finding even rudiments of api)endagcs on any of the anterior 

 segments of the abdomen. The smallest individual in which I have 

 been able to detect ovigerous appendages is a specimen, with the 



