﻿South African Crustacea. 



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Thenus from Scyllanis, Ibacus, and Parribacus. The mouth- 

 parts of the different genera are described by de Haan, whose 

 work also shows that, while there are 21 pairs of branchiae in 

 Scyllaricles, Parribacus, Ibacus, and Thenus, there are only 

 19 pairs in Scyllarus. As, according to Miss Eathbun, Sctjl- 

 larus americanus, S. I. Smith, is usually not more than half 

 an inch long, great size is not an invariable characteristic of 

 the " Mother-Lobsters." 



Thenus oriektalis (Lund). 

 1705. Ursa Cancer, Eumphius, D'Amboinsche Eariteitkamer, vol. 1, 



p. 3, pi. 2, fig. D. 

 1758. Cancer arctus (part), Linn., Systema Naturae, ed. 10, p. 633. 

 1775. Scyllarus arctus (part), Fabricius, Syst. Entom., p. 413. 

 1793. „ ,, ,, Fabricius, Ent. Syst., vol. 2, p. 477. 



1793. Cancer {Astacus) arctus, Herbst (not arctus, Linn., sensu 

 strictiore), Krabben and Krebse, vol. 2, part 3, p. 80, 

 pi. 30, fig. 1. 

 1793. Scyllarus orientalis, Lund, Skrivter Nat.-Hist.-Selsk., vol. 2 



part 2, p. 22. 

 1798. „ „ Fabricius, Suppl. Ent. Syst., p. 399. 



1803 ,, „ Latreille, Hist. Nat. Crust. Ins., vol. 6, 



p. 181. 



1815. Thenus incJicus, Leach, Trans. Linn. Soc. London, vol. 11, 



p. 338. 



1816. „ ,, Leach, Encycl. Brit., ed. 5, Suppl., p. 419. 

 1825. Scyllarus orientalis, Desmarest, Consid. gen. Crust., p. 182, 



pi. 31, fig. 1. 

 1837. Thenus orientalis, Milne Edwards, Hist. Nat. Crust., vol. 2, 

 p. 286, and Eegne Animal, illustr. ed. 

 undated, pi. 45, figs. 2a-c. 

 1888. „ ,, Bate, Eep Voy. Challenger, vol. 24, p. 66. 



1888. ,, ,, de Man, J. Linn. Soc. London, vol. 22, 



p. 261. 

 1891. „ ,, Ortmann, Zool. Jahrb., vol. 6, p. 46. 



1914. ,, „ Balss, Abhandl. K.Bayer, Ak.Wiss., vol. 10, 



Suppl. 2, p. SO. 

 Ortmann assigns the species to Eumph, though without 

 using Eumph's name for it. Jonston, Hist. Nat. de Exang- 

 vibus aqvaticis, p. 21, pi. 4, figs. 3, 4, 8, 12, 1767, adopts the 

 name Ursa major for three figures, 3, 4, 12, which on his 



