S. T. Smith — Early Sta.f/es of Hi.ppa talpoida. 331 



segment of a circle, tilling nn arcuate siniis in the posterior margin 

 of the carapax; witli which, however, it is not yet consolidated, as 

 in the adult, for it is slightly movable upon the caiapax and usually 

 separates from it and remains attached to the second segment when 

 the abdomen is torn away from the cephalo-thorax. As usual in the 

 megalops-stage, and in the larval forms of Podophthalmia generally, 

 it is without appendages. The second-segment is about five times as 

 broad as long, three-fourths as broad as the carapax, and neai-ly twice 

 as broad as the third segment; its great breadth being a result of a 

 broad, lamellar expansion each side. The anterior margin is nearly 

 straight, and the lamellar portion each side slips slightly over the 

 posterior margin of the carapax, when the abdomen is folded beneath 

 the sternum. The lateral margins are very oblique and converge 

 rapidly to the posterior margin, which is no longer than the breadth 

 of the third segment, for the reception of which it is excavated 

 throughout nearly its whole extent ; but the lateral expansions do 

 not project so far posteriorly each side of the third segment as they do 

 in the adult. The margins each side are armed with a few stitf seta?. 

 The third segment is about as long as the second, the lateral margins 

 only slightly projecting and rounded and, together with the anterior 

 margin, armed with a few setie. The fourth and fifth segments are 

 nearly as long as the third, and each successively, very slightly nar- 

 rower than the one in front of it ; they both project very little 

 laterally and are sparsely armed on the lateral and anterior margins 

 with stifl" setae. The sixth segment is nearly as wide as the fifth and 

 only a little wider than long, both the anterior and posterior margins 



meme forme, et les anneaux suivans presentent aussi la disposition que nous avoiis 

 deja remarqnee chez ces Crustaces." 



Without any reference to the homology of the parts, so clearly shown by their 

 structure and appendages in the megalops-stage, there need be no question in regard 

 to the broad, winged segment in both Hippa and Reniipes being the second, from the 

 fact that it bears the first pair of large ovigerous appendages in the female, and that, 

 if it be the first, that somewhere, two of the succeeding segments must have become 

 completely consolidated into one, although there is no indication, in the segments 

 themselves, of any such consolidation. Quite as conclusive also is the fact that, in the 

 allied genus Albunea, while all the segments of the abdomen are perfectly distinct and 

 movable one upon the other, and the anterior ones have nearly the same form as in 

 Hippa and RemijMS, the small first segment is entirely free from the carapax, though 

 fitting closely in a deep sinus in its posterior margin, as described by Milne-Edwards 

 in the passage just quoted. Although this consolidation dorsally of the first segment 

 of the abdomen with the mandibular segment is of rare occurrence in the Malacostraca, 

 it certainly seems no more abnormal than the appearance of the last thoracic segment 

 in the same position, would be. 



