S. I. Smith — Early Stages of Hippa talpoida. 323 



a little stouter than the palpus, of which only the elongated dactylus 

 and the stout propodus are clearly distinguishable. The first four 

 pairs of thoracic legs (e, d, e,/\ fig. 9) show clearly only the distal 

 segments, but, of these, the propodus and dactylus have already 

 assumed the peculiar form which characterizes them in the niegalops- 

 stage and in the adult, the propodus in the first, second, and third 

 pairs being elongated into a prominent lobe on the inside at the 

 distal extremity, while in the fourth pair (/', fig. 9) this segment is 

 truncated at the distal end. The posterior thoracic legs (g, fig. 9) 

 are slender, cylindrical, and the three distal segments are nearly equal 

 in length, but there is no indication of the cheliform character which 

 they assume in the megalops-stage. The branchial processes (A, fig. 9) 

 above the bases of the legs have become more conspicuous than in the 

 earlier stages and represent the full number of branchite in the adult, 

 there being one above the base of each external maxilliped and two 

 each upon the four anterior thoracic legs, making nine pairs in all. 



The first segment of the abdomen is still in the same condition as 

 in the second stage, not distinctly differentiated from the thorax, and 

 the remaining segments themselves retain very nearly the same form 

 as before. The abdominal legs of the second, third, fourth, and fifth 

 segments (Plate XLV, fig. 4) are as long as the segments to which 

 they belong, but are still sack-like, the base separated from the 

 terminal portion by an obscure articulation, but with no indication 

 of the separation of the outer from the inner lamella, and the 

 appendages are evidently of no functional importance. The sixth 

 segment is still closely Tinited with the telson, although some of 

 the specimens show a slight indication of the approaching articula- 

 tion. The appendages of the sixth segment (Plate XL VIII, fig. 12) 

 have increased very much in size, and the outer lamella (b) has 

 become narrow-oval in outline, about a third as broad as long, with 

 the tip rounded and furnished with six strongly curved setie, of 

 which the third from tlie oiitside is much longer than the lamella, 

 itself, while all the others are much shorter and decrease in length 

 each way from the longest. The inner lamella (e, fig. 12) is two- 

 thirds as long as the outer, nearly as broad, and regularly oval in 

 outline, without hairs or set». 



The telson (Plate XLY, figs. 3 and 4) has the same form as in the 

 previous stages. Its posterior margin (Plate XLVIII, fig. 15) is 

 armed Avith twenty-six ciliated spines having the same arrangement 

 as in the earlier stages. The number of denticles in the interspaces 

 between the spines is very much increased, there being three between 



