SoutJi African Crustacea. 65 



Themis from Scyllarus, 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 

 Scyllarides, Parribacus, Ibacus, and Themis, there are only 

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

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

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

 the " Mother-Lobsters." 



THEXUS ORIEXTALIS (Lund). 



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



p. 3, pi. 2, tig. 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 oricntalis, 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. Thcnus indicus, Leach, Trans. Linn. Soc. London, vol. 11, 



p. 338. 



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

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



pi. 31, fig. 1. 



1837. Themis oriental is, Milne Edwards, Hist. Nat. Crust., vol. 2, 



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

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



1888. ,, ,, Bate, Eep Yoy. Challenger, vol. 24, p. 66. 



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



p. 26J. 



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



1914. ,, ,, Balss, Abhandl. K. Bayer, Ak. ^Viss., vol. 10, 



Suppl. 2, p. 80. 



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 



