REPORT ON THE AMPHIPODA. 1271 



includes the genus Astacus, and at p. 415 he gives the following definition of Astacus 

 crassicoiviis : — 



"7. A. antennis posticis bifidis, thorace articulato, pedibus sexti paris longissimis. 



" Habitat in Oceano americano. Mus. Banks. 



" Corpus parvum, rubescens. Thorax oblongus, subcylindricus, dorso carinatus, 

 antice retusus absque rostro, articulatus ; articulis octo subsequalibus. Antennae anticse 

 corpore longiores, setaceae, crassiuscuke. Abdomen angustaturn, quinque-articulatum. 

 Pedes utrinque octo, omnes simplices ; sexto duplo longiori, fernoreque serrato. Cauda 

 stylis sex exsertis, filiformibus." 



By Herbst in 1796 this species is called " Das Dickhorn. Cancer (Garnmarellus) 

 crassicornis" (see Note on Herbst, p. 61), but, though he correctly places it in the midst 

 of Amphipoda, he leaves it in so much obscurity that later writers have not accepted it 

 as an Amphipod. By the expressions " antennis posticis bifidis," and " pedes utrinque 

 octo," it seems to be entirely excluded from this group, but fortunately there is in the 

 Museum Banksianum, under the care of Dr. Giinther in the British Museum at South 

 Kensington, a figure of Cancer crassicovnis, signed " Sydney Parkinson pinxt. 1768," 

 to which the description by Fabricius clearly refers. The bifid hinder antennae were 

 perhaps assigned to it as a matter of course on the presumption that the species belonged 

 to the genus Astacus ; the eight segments attributed to the thorax probably include the 

 head, and possibly the lower antenna? of a male specimen were counted as the first 

 pair of legs, by this means making the total number of legs eight pairs, and the longest 

 pair the sixth in order instead of the fifth ; if these or some equivalent explanations be 

 accepted, it wdl then, I think, be readily admitted that the Astacus crassicornis of 

 Fabricius is the earliest described species of the genus since successively named Scind, 

 Tyro, Clydonia, while it is beyond all question that Sydney Parkinson's figure of 

 Cancer crassicornis is the earliest known representation of any species of that genus. 



The first intelligible description, however, of a species of Scind appears to have been 

 that given by Milne-Edwards in 1830 of Hyjyeria cornigera, which in 1840 he made 

 the type-species of the genus Tyro. In the meantime Prestandrea in 1833 had described 

 the genus Scind. For the curiously worded definition, see Note on Prestandrea, 1833 

 (p. 151). The difficulties introduced into that definition by misprints and bad Latin 

 will disappear on a comparison of it with the specific description which Prestandrea gives 

 of Scind ensicorne, and which for facility of comparison with the other generic accounts 

 I here reproduce in English : — 



" Body triangular, with the lower surface broader than the lateral, five lines long, 

 dorsally carinate ; lateral margins prominent ; the colour of the body is deep orange-red, 

 although in the middle there are one or two segments whitish. Head truncate, depressed, 

 with two raised divergent lines, which starting from the beginning of the carina, where 

 they form an acute angle, terminate at the base of the upper antennae. Upper antennae 



