Boone, Crustacea, Cruise of "Alva,'* 1931 205 



Distribution : New Caledonia. 



Material examined : Ten males and fourteen females (thirteen 

 with eggs), collected at Noumea, New Caledonia, September 19, 1931, 

 hyi\iQ''Alva." 



Color : Violaceous brown. 



Technical description : This species is readily distinguished from 

 the foregoing, M. convexus, by the fact that the carapace is more squar- 

 ish, the length being four-fifths of the width; the sides are less con- 

 vergent posteriorly, nearly parallel, up to the point where they curve 

 above the fifth legs. The true frontal margin is also different, being 

 squarish, scarcely at all constricted between the orbits, dorsally di- 

 vided into two lobes by a distinct median longitudinal sulcus. The 

 superior orbital margin is slightly sinuate and terminates distally in a 

 blunt right-angled tooth ; behind this, on the lateral margin and sepa- 

 rated from it by a wider sinus than exists in M. convexus, is the first 

 lateral tooth, also blunt right angled. The inferior orbital margin is 

 dorsally visible, oblique, a little bowed, curving backward under the 

 anterolateral angle. While the dorsal surface of the carapace is con- 

 vex in both directions, it is less sloping toward the lateral margins 

 than is that of M. convexus. The regions are more decisively defined in 

 the present species. The gastric region is circumscribed and radiating 

 from the cervical groove on either side is a curved sulcus extending to 

 between the lateral teeth of the margin. Behind this is a second sulcus 

 branching from the cervical groove and vanishing near the lateral 

 branchial margin. The cardiac region is circumscribed and the intes- 

 tinal region is defined clearly. There are very few dorsal granules in 

 the present species, those present being in the hepatic and outer 

 branchial regions. There is abundant fine pubescence which is espe- 

 cially thick on the lateral and posterior portions of the dorsal surface. 

 The sidewalls are high, pubescent, granulose. The male belt is seven- 

 segmented, but differs from that of M. convexus in that it has the sev- 

 enth segment abruptly much narrower than the sixth and quite small, 

 subtriangulate, with the apex rounded. 



The eyestalks of the present species are shorter, conforming to the 

 more compact body, but they do extend the entire length of the cara- 

 pace ; the cornea is large, terminal, with a small rounded process of the 

 stalk at its outer tip. 



The antennulae and antennae afford no specific characters. 



The external maxillipeds are similar to those of M. convexus. 



