REPORT ON THE CRUSTACEA MACRURA. 



559 



First pair of pereiopoda unequal, the larger pair long, ovate, and the smaller 



elongate. 



Three posterior pairs of pereiopoda triangulate. 



Length, entire, 



„ of carapace, 

 Depth of carapace, 

 Length of pleon, 



,, of telson, 



,, of large chela, 



,, of daetylos of large chela, 



,, of small chela, 



,, of daetylos of small chela, 



Habitat. — Off Bahia. Three specimens ; one female, two males. 



Station 113a, September 2, 1873 ; lat. 3° 47' 0" S., long. 32° 24' 30" W.; off 

 Fernando Noronha ; depth, 7 to 25 fathoms ; bottom, volcanic sand and gravel. One 

 specimen, female (6 mm. long), with ova. This specimen has lost its longer chela. 



St. Paul's Eocks, the Atlantic. Two specimens, females (9 mm. long), from which 

 ova had just been cast. 



This species appears to be common in the tropical and temperate regions of the 

 Atlantic Ocean from Bermuda in the north to St Paul's Eocks in the south. 



Observations. — Kingsley in his full description of this species says that the larger 

 hand has " a strong spine (tooth) above, and a smaller one near it at the articulation 

 of the daetylos." I only saw this tooth conspicuously developed in one specimen. As 

 a rule it is not a specific character, as in a great number of specimens of this and other 

 species a tooth normally exists at the dactyloid hinge, but it is frecjuently rudimentary 

 or rubbed down by use. 



The same author also says that " in some specimens the ocular spines are wanting ; 

 in others the point is truncate, no spines being present. The proportions of the joints 

 of the carpos of the second pair also vary." 



"The relative length of the rostrum and ocular spines can be of no great importance 

 when they vary as I have shown." He says, moreover, that he was not able to 

 separate specimens from Pearl Island, Bay of Panama, from Floridan examples. "The 

 antennular spines also are not incurved. Other than these I can detect no important 

 points of difference." 



One peculiarity has been overlooked by previous observers, namely, that the daetylos 

 has an extremely long and robust tubercle projecting posteriorly, and generally lying 

 inserted in a circular hollow in the median line at the base of the pollex ; anterior to 

 this tubercle is a second smaller one. The posterior projecting tubercle is common to 

 many species, but in this it is remarkable for its length. 



