392 ME. A. D. MIOKAEL OK HTPOPl, 



Average length of legs — 1st and 2nd pairs about "06 millim. ; 

 3rd and 4tli pairs about "08 millim. 



Colour. Tellowisli cbitiuous -brown, of medium tint. The 

 wbite excretory organs sliow through the dorsal surface, as in 

 the male. 



Textiore. Chitinous, hard, and polished, particularly the an- 

 terior part of the carapace, which is slightly transparent. 



General form oval, but so short and broad as to be nearly 

 circular. This form varies a little, not only in different spe- 

 cimens, but in the same, according to the action of the muscles, 

 the lateral parts of the carapace being slightly flexible. 



The whole of the anterior part of the body is covered by a 

 semilunar buckler, greatly resembling that of Limulus. This 

 buckler projects far beyond the body both anteriorly and laterally, 

 and extends as far back as the insertion of the 4th (posterior) pair 

 of legs. The three anterior pairs of legs are entirely covered by 

 this buckler when the creature is at rest, and almost covered by 

 it at other times. The portion of the body posterior to the in- 

 sertion of the 4th pair of legs is also covered by a projecting 

 carapace; but this, instead of being fused into one mass, is 

 clearly divided into three segments. 



Geplialothorax. Small, much more distinctly divided from the 

 abdomen than in the male. Eostrum shorter, broader, and more 

 chitinous than in the male; it is usually carried folded down 

 against the ventral surface. The mouth-organs, which are diffi- 

 cult to make out, appear less rudimentary than those of the 

 male. The anterior pair of rod-like projections have become 

 more substantial organs. 



The abdomen, although much smaller than the carapace, is large 

 in proportion to the cephalothorax ; it approaches the circular 

 form, but on the ventral surface bears a thin, colourless, shield- 

 shaped plate, more plainly seen at its anterior than its posterior 

 limit, the anterior angles projecting and covering the insertion 

 of the third pair of legs. 



There are two rows of colourless spines on the dorsal surface 

 of the carapace, which may stand upright or lie backward; a few 

 similar spines nearer the edge, and two smaller pairs near the 

 posterior margin. There is a sternum, apodemata, and epimera, 

 forming a skeleton on the ventral surface, as in the male. 



Legs. The first two pairs rather the shortest, the first j)air 

 thicker than any other (except the basal joint of the fourth). 



