South African Crustacea. 245 



1900. Cymonomus, A. M.-E. et Bouvier, Crust. Dt'cap. Travilleur 



et Talisman, p. 34. 



1902. A. M.-E. et Bouvier, Mem. Mus. Comp. Zool., vol. 



27, p. 81. 



1903. Lankester, Q.J.M.S., vol. 47, p. 450. 



1904. Doflein, Valdivia Exp., Brachyura, pp. 33, 152, 190, 



282. 



1905. ,, Alcock, Ann. Nat. Hist., ser. 7, vol. 15, p. 565. 

 1908. H. J. Hansen, Ingolf-Exp., Crust. Malac., vol. 3, 



pt, 2, p. 20. 



1916. Ible, Zool. Anzeiger, vol. 46, p. 360, and Siboga- 



Exp., Mou. 396', p. 118. 



CYMONOMUS TRIFURCUS, n. sp. 

 Plate C. 



The present species seems to be nearly allied to the East African 

 form which Doflein figures and briefly describes under the name 

 " Cymonomus granulatus Valdiviae, Lank." (loc. cit., pp. 33, 284, pis. 11, 

 fig. 5 ; 12, figs. 1-3 ; 38, fig. 8 ; 44, fig. 7). But the illustration, most 

 suggestive of a real alliance, by a three-pronged rostral plate, is itself 

 distinctive, the true rostrum being in Doflein's form not granular, 

 shorter than the eye-stalks, and more nearly parallel with them. Also 

 his drawing of the third maxilliped shows the fourth joint more 

 strongly produced beyond the insertion of the fifth joint and the 

 principal joint of the exopod extending beyond the eudopod. 



In the present species there is no suture or line of demarcation 

 dorsally separating the trifurcate rostral plate from the rest of the 

 carapace. The widely-divergent lateral prongs, however, in ventral 

 view, show a little rounded knob apically, white and smooth as pre- 

 served, presumably the vestigial eye. Milne-Edwards and Bouvier 

 state that in this genus the segments of the pleon are all distinct in 

 both sexes, but their figures show only six segments. Alcock also 

 speaks of the segments being all distinct. In the form here considered 

 I could only find a pleoii with six segments, the second and third being, 

 perhaps, consolidated. The French authors say that the males have 

 two pairs of pleopods modified as sexual organs, nearly resembling 

 those of the Dromiidea, except that the terminal article of the second 

 pair is not stiliform. Our South African form, on the contrary, has 

 in this pair a sharp stiletto-like apex, but in situ both pairs have their 

 terminals strongly folded inwards instead of being stretched back- 

 wards as necessitated in the figures to show the details of their 



