308 Annals of the South African Museum. 



ACHELOUS CRASSIMANUS, M c Leay. 



1838. Achelous crassimanus, MLeay, Annulosa of S. Africa, p. 61. 



M c Leay follows the brief descriptions by the note: "This 

 large crab has a shell which is about five inches long by seven 

 wide. The teeth of the cephalothorax are triangular, sharp, 

 and nearly equal. The fore-feet are nearly equal in size. The 

 abdomen of male has seven joints. It has been only known, 

 as yet, to occur in deep holes, which it makes in the mud 

 islands near the mouth of the Zwartkops River islands that 

 are only visible at low water." 



1843. A. c., Krauss, Siidafrik. Crust., p. 23. 



Krauss adds nothing to M c Leay's account, except that the 

 mouth of the Zwartkop is in the district Uitenhage. In the 

 immediately following notice of Chary bdis smith ii, he declares 

 that MLeay never specifies the locality at which a species was 

 found, although the case of Achelous crassimanus is an obvious 

 exception. It is not improbable that Alcock's suggestion may 

 be right (J. A. S. B., vol. Ixviii., p. 28) that M c Leay's species is 

 a synonym of Scylla serrata (Forskal). But the pleon of the 

 male in that genus is of five segments, while in M c Leay's 

 species it is said to be of seven. 



GEN. SCYLLA, de Haan. 



1833. Scylla, de Haan, Crustacea Japonica, decas prima, p. 11. 

 1899. S., Alcock, Journ. Asiat. Soc. Bengal, vol. Ixviii., pt. 2, p. 27. 



SCYLLA SERRATA (Forskal). 



1775. Cancer serratus, Forskal, Descript. Anim. in itin. oriental!, 



p. 90. 

 1843. Scylla serrata, Krauss, Siidafrik. Crust., pp. 12, 25. 



" This species is at home at the mouths of some little 

 brooks in Natal Bay, where it digs large and deep holes in the 

 mud among the roots of Rhizopliora mucronata, Lam., and 

 Bruguiera gymnorhiza, Lam." 



Krauss also declares it to be the largest and strongest 

 species among the South African Crustacea, giving its breadth 

 as six inches one line and length as four inches two lines. 

 These measurements are inferior to those given by M c Leay 

 for his Aclielous crassimanus. But Krauss's account on the 

 whole makes it almost certain that M c Leay's species should 

 be included under Forskal's, the chief doubt arising from the 



