﻿G2 Annals of the South African Museum. 



iictual specimen. With regard to the application of this description 

 I asked the advice of my friend, Dr. W. T. Caiman, D.Sc, who, 

 after consulting ^Yith his colleague, Mr. C. Tate Regan, writes : " He 

 agrees with me that it applies very well indeed to a specimen of 

 ' Scyllams arctus,' but cannot, by any stretch of imagination, be 

 made to fit specimens of ' Parribacus antarcticus ' or of ' Themis 

 oricntalis.' . . . Only S. arctus can be described as ' aculeis inter 

 oculos circiter 10 ' or as having the carapace ' quinquefariam 

 antrorsum aculeatus,' The description of the'cauda' puzzled me 

 a good deal till Mr. Regan pointed out that the grooves on each 

 abdominal somite except the first and last do really define three 

 areas, the first smooth, the second rough, and the third rough and 

 triply emarginate behind. Regan also makes the suggestion which 

 I think probably right, that ' digito brevissimo ' refers to a very 

 minute tooth on the concave mai'gin of the dactylus of the first 

 peraeopods." 



In 1775, as Gill, Miss Rathbun, and Sherborn have stated, 

 Fabricius instituted the genus Scyllarus for Cancer arctus, Linn. 

 To this genus he added the species S. australis in 1781, and again 

 recorded these two species in 1793 (Ent. Syst., vol. 2, p. 477), with- 

 out reference to his own earlier records or any indication that the 

 genus was not a new one. Under S. arctus he gives the old cos- 

 mopolitan distribution and mixture of references, as though quite 

 unaware that they belong to a variety of species, here also as in 

 1781 quoting Rumph. Mus. tab. 2, fig. 6, D, by mistake for C, D. 

 My own mistake in 1908 must be acknowledged. It consisted in 

 accepting 1793 as the date for the genus Scj/Uarus and the species 

 S. australis, in place of 1775 for the one and 1781 for the other. The 

 year 1793, however, is rather deeply involved in the interests of the 

 present family. For while Fabricius was leaving his genus in its 

 primitive disorder, two of his contemporaries were independently 

 making a systematic revision of it. Herbst (Krabben und Krebse, 

 vol. 2, part 3, pp. 80, 82, 83, pi. 30, figs. 1, 2, 3), mentioning but not 

 adopting Scyllarus, assigns to Cancer (Astacus) three species which ■ 

 he named respectively arctus, ursus major, ursus minor. Here it 

 should be noted that the invaluable " Index Animalium " makes 

 a slight slip by assigning these three names to 1792, which would 

 have been correct had the descriptions occurred in part 2, ending 

 with p. 78, but Sherborn now accepts Miss Rathbun's date 1793 for 

 parts 3 and 4 of Herbst's second volume. This robs Herbst of any 

 unquestionable precedence over N. T. Lund, who in the same year 

 1793 (Acta Hafn. or Skrivter af Naturhistorie-Selskabet, vol. 2, 



