74 



STALK-EYED CRUSTACEA. 



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^r - ^-^ 



they show a little when the animal is viewed from above. The basal seg- 

 ment of the antennEe, moreover, is more exposed from above than it is in 

 the more typical species of Munida. 



The lateral rostral spines, or supraocular spines, are curved upward more 

 than the median rostral spine, and the three are nearly parallel ; the lateral 

 spines reach about half way to the tip of the median ; all three are micro- 

 scopically splnulose on their upper edge. There are two pairs of spines on 

 the anterior part of the gastric region in line with the lateral rostral spines. 

 Of these two pairs the anterior is the larger. There is also a longitudinal 

 line of spinules in the median line between the two pairs just spoken of The 

 arrangement of the other spines on the anterior portion of the carapace will 

 be best understood by reference to the figure on Plate XVI. The cardiac 

 area is somewhat sunk below the level of the surrounding parts, its anterior 

 margin is denticulated, with a larger spine on each side. Tiie lateral mar- 

 gins of the carapace are armed with ten or eleven spines, the one on the 

 anterolateral angle being the longest. The second abdominal segment is 

 ornamented with a transverse row of eight small spines. The other abdomi- 

 nal segments are normally destitute of spines, but in a few of the many 

 specimens before me there are two or four small spinules on the third seg- 

 ment. The pleura) of the third, fourth, and sixth abdominal segments are 

 acute, the rest blunt. The eyes are large and are provided with rather long 

 cilia on the edge of the cornea. The basal joint of the antenna is armed 

 with a long and sharp spine which reaches forward beyond the eyes ; the 

 second joint also has a long spine on each side. The chelipcds are long and 

 hairy ; the merus, carpus, and basal part of the propodite are spiny, the 

 fingers long, slender, the cutting edges straight and finely spinulous.* The 

 ambulatory appendages are setose, the upper and lower edges of the merus 

 are spinulosc, and there is, moreover, a row of spinules on the outer surface, 

 this external line of spinules being best developed on the proximal end of the 

 segment; the carpus is armed with small spines on the upper margin and 



* la some of the males the chela is broader than in others, and the basal part of ilic propodal digit is 

 curved so that there is a distinct gap at the base of the fingers, with one or two rather prominent teeth on 

 the base of the cutting edge of the dactyliis. This difference in the form of the chela is generally found among 

 the males of the different species of M?mirla^ and has been referred to by Henderson (Challenger Anoniura, 

 p. 127), as a case of dimorphism. I have elsewhere (Amcr. Joiirn. Sci., 3d Ser., XXVII. 42-44, 1881) shown 

 that the two forms of the male in the genus Camhams are alternatlrig stages in the life of the same indi- 

 vidual, one phase being assumed during the breeding periods, the other during the Iiitervcuiia; seasons or 

 sexual quiescence. Jules Bonnier (Comptes Eendus de TAcad. Sci., CXI. 987, 1S90) has shown that the 

 same condition of things exists among the AmpUpoda, I have no doubt that the two forms of the male in 

 the genus Munirla are to be explained in the same way. 



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