314 DE. J. G. DE MAN ON SPECIES OF PAL.EMON 



fingers, is 4'5 mm. broad and 3"5 mm. tliick in the middle. The fingers shut close 

 together ; the dactylus is armed with two small teeth, the immobile finger with one 

 besides the tooth at the extremity of the cutting-edge. 



In the young female No. 23 finally the rostrum reaches to the end of the scapho- 

 cerites and agrees with the other specimens. The outer footjaws project for two-thirds 

 of their terminal joint beyond the lower peduncles, and the legs of the first pair for 

 a fourth of the carpus beyond the distal end of the scales. The larger leg of the 

 second pair is the left (fig. 52), measuring just two-thirds of the body. The merus is 

 1 mm., the carpus 1'33 mm. broad, at their distal ends, and the latter projects for a 

 third of its length beyond the antennal scales. The palm is 1-52 mm. broad and 1"27 mm. 

 thick in the middle ; as usual, the dactylus (fig. 53) is provided with two, the index with 

 one small tooth behind the distal tooth at the end of the cuttino'-edare. The let^s of the 

 third pair reach to the extremity of the scaphocerites. 



The larger leg of the second pair of the large male (No. 7) from Catumbella has a pale 

 yellowish-green colour ; the carpus appears on the inner, the palm on its outer side dark 

 green, and the fingers are also dark green to their tips, but they show a yellowish-red 

 tinge at their proximal ends and at their articulation. In the other specimens these legs 

 are of a pale flesh-colour, reaching to the base of the fingers ; the latter are dark bluish 

 coloured, often with pale tips. 



It is, indeed, a pity that in Liberia and in the River Prah no younger specimens have 

 been collected or at Catumbella individuals of larger size, for then it would have been 

 possible to decide whether the more slender appearcmce of the second legs of the Angola 

 specimens is caused by their younger age or not ; in the latter case the Angola form 

 would be a distinct, new variety o/'Palsemon jamaicensis. Benedict lias already observed 

 [1. c.) that specimens from the Quanza River at Cunga are "a little more slender" than 

 others from Old Providence, West Indies. If further researches should prove this to be 

 really the case, I propose for this variety the name angolensis. 



Pal^mon (Macrobrachium) Olfeksii, Wiegm. (Plate 20. figs. 64-74.) 



Palcemon Olfersii, Wiegmann, in Arcliiv fiir Naturg. Jahrg. 2, toI. i. 1836, p. 150; GreefE, in 

 Sitzungsber. Gesells. zur Beforderung ges. Naturw. Marburg, 1882, No. 2, p. 30; Ortmauu, iu 

 Revista do Museu Paulista, No. ii. 1897, p. 212, Est. i. figs. 10 & 11 ; Aurivillius, /. c. p. 23. 



Palamon spinimanus, H. Milne-Edwards, Hist. Nat. Crust, ii. p. 399; von Martens, in Archiv fiir 

 Naturg. 1869, p. 26, Taf. ii. fig. 3. 



Bithynis Olfersii, Rathbun, The Brachyura and Macrura of Porto Rico, Washington, 1901, p. 124. 



One adult male from the River Prah, Ashantee. (British Museum.) 

 60 young specimens, a third of which are males, from the river at Catumbella, near 

 Benguella. (Private collection.) 



The adult male from the River Prah is 58 mm. long from the tip of the rostrum to 

 the end of the telson. The rostrum (fig. 54) reaches almost to the end of the antennulary 

 peduncles, is slightly directed downward, and armed above with 16, below^ with 5 teeth ; 

 the upper teeth are equal, small, equidistant, and five are on the cephalolhorax. The 

 telson tapers rather much towards the triangular pointed extremity and the anterior pair 

 of spinules is situated just before the middle. The outer footjaws are as long as the 



