GAMMARTD.E. 203 



This well-known species is taken as the type of Gammaracan- 

 thus ; and, if compared with the type of the genus Gammarus, it will 

 be found, wliil.st liaving many cliaracters in common, to differ in 

 gi'ueral form as well as in structiu'al detail. It ajjproaches nearer to 

 Amaihia than to Gammanis. 



2. Gammaracanthus mucronatus. 



Gammarus mucronatus, Sai/, Jouni. Acad. Fliilud. i. pt. 4. p. 376. 

 lidwards, Ann. des Sc. Nat. xx. p. 3G8 ; Hist, dcs Crust, iii. p. 1-5. 



•• Eighth, ninth, and tenth segments of the body mucronate above-. 

 Eyes irregularly reniform, blackish, truncate above, and forming 

 an angle towards the base of the upper antennae. Antennae sub- 

 equal : superior pair with about twenty articuli in the flagellum ; 

 secondary appendage attaining the tip of the fourth articulus. 



" Length not half an inch. 



" Uah. Florida, coast of the United States. 



'* In the male, the dorsal teeth are often less distinct tlian in the 

 female ; sometimes they are wanting on the eighth and tenth seg- 

 ments, and very small upon the ninth." — Say. 



3. Gammaracanthus macrophthalmus. 



Gammarus niacroptlialmus, aS'^/w^j'Jao//, Marine Invert, of Grand Manan, 

 p. 55. 



" This species strongly resembles Amathia Sabinii in colour and 

 general appearance. The back, however, is carinated only at the 

 pleon, which readily distinguishes it. The secondary appendage of 

 the superior antennae is minute and scarcely perceptible. Eyes very 

 large, subreniform, near each other. Coxae small. Fourth pair of 

 pleopoda as long as the fifth, both having the outer rami shorter 

 than the inner ones; last pair with broad lanceolate rami, shorter 

 than in A. Sahinii. Colour sometimes bright crimson, but usually 

 mottled red and flake-white ; very variable. 



'* Length Oo inch: of the inferior antennae, which are the longer, 0-2. 



" Hah. Dredged on rocky bottoms in the Laminarian zone, and 

 occasionally taken at low-water mark." — Stimpson. 



65. GAMMARUS. 



Gammarus, Fuhriciiis, Ent. Syst. ii. p. 514. 

 Lutreille, Hist. Nat. des Crust, vi. p. 315. 

 Leach, Edinb. Enei/c. art. Cntstaceology, vii. p. 402 ; Trans. Linn. 



S()c. xi. p. .359. 

 Lamarck, Jlist. des Anim. satis Vert. v. 

 J)rs)niirest, Consid. sur les Crust, p. 2(J5. 



Edwards, Ann. des Sc. Nut. xx. ; Jlist. des Crust, iii. p. 42, Divi- 

 sion 1. A. a. 

 Kriiijer, CrnnJ. .inifip. p. 27. 



