142 Bulletin, VanderhiU Marine Museum, Vol. Ill 



ciliate; the second and third articles are also short, cylindrical and 

 lie beneath the scaphocerite, extending about one-third its length; 

 the flagellum is 200 mm. long, multiarticulate and extends beyond the 

 extended chelipeds. 



The external maxillipeds are slender, leg-like, arched, well 

 separated. 



The first legs are small, slender ; the basis and ischium rather thick 

 and with many small bristles ; the merus is twice the length of the 

 ischium and slenderer; the carpus is one and one-half times as long 

 as the merus and slenderer; the propodus is short and weak, being 

 only two-fifths as long as the carpus; the fingers comprising one-half 

 this length and being slender, subequal, setose. 



The chelate second legs are equal, each measurin"g 190 mm. long 

 and being slender, cylindrical, the ischium not quite one-half the 

 length of the merus; the merus is 37 mm. long; the carpus 54 mm. 

 long; the propodus including the fingers is 77 mm. long; the fingers 

 are subequal, each 32 mm. long, subcylindrical, with the tips decidedly 

 upcurved. The ischium, merus, carpus and palm of the propodus 

 are set all over with rows of sharp corneous spines; the fingers are 

 entirely covered with a fine velvety pubescence. 



The third, fourth and fifth legs are slender, subequal, proportioned 

 about as in M. olfersi, the propodus about three times as long as the 

 dactyl and armed along its inferior lateral margin with a row of 

 spinules. 



Synonymy. — Palaemon acanthurus A. F. A. Wiegmann, Archiv. f. 

 Naturg., vol. 2, S. 150, 1836.— A. E. Ortmann, Zool. Jahrb. V. 

 Abth. f. Syst., p. 720, taf. 47, fig. 5, 1890. 

 Palaemon forceps H. Milne Edwards, Hist. Nat. Crust., vol. 2, p. 397, 

 1837. — H. DeSaussure, Mem. Hist. Nat. du Mexique des Antilles 

 et des Etats Unis, re livre, p. 51, 1858. — E. von Martens, Archiv. 

 f. Naturg., vol. 35, Jahrb. 1869, S. 28, taf. 2, fig. 4.— S. I. Smith, 

 Trans. Conn. Acad. Arts and Sci., vol. 2, p. 24, 1869. 

 Palaemon (Eupalaemon) acanthurus J. G. DeMan, Ann. Soc. Roy. 

 Zool. et Malcol. de Belgique, vol. 46, p. 243, 1911. 



Macrobrachium olfersll (Wiegmann). 



Plate 50. 



Diagnostic characters: In the field this species is readily dis- 

 tinguished from all its associates by the vivid purplish-blue of the 

 great cheliped. The fact that this hand is dilated, covered with numer- 



