212 



AMPniPOnA NORM ALIA. 



12. Gammarus ornatus. (Platk XXXVII. fig. 8.) B.M. 



Gammani.s ornatus, Edwards, Ann. des Sc. Nat. xx. p. 372. pi. 10. f. 1 ; 



Ili.-it. des Crust, iii. p. 47. 

 GainiTianis fucicolus, >Sfi>npson, MS. 



Ganiiuariis Pl'ulex, Stimpson, 3I(iri»e Invert. Grand Manan, p. 55. 

 Ganimaru3 PLocusta, Gould, Invert. 3Iass. p. .3.34. 



Eyes long, rcniform. Superior antennae having the first joint of the 

 peduncle longer than the .second, the second longer than the third ; 

 flagellum longer than the peduncle. Inferior antcnnfc having the 

 peduncle longer than the peduncle of the superior ; flagellum not 

 longer than the last joint of the peduncle. First pair of gnatho- 

 poda ha\'ing the propodos long-ovate, not broader than the carpus ; 

 palm obIi(}uc, concave, armed with a long and a .short blunt spine, 

 and defined by an angle furnished with two or three short obtuse 

 spines. Second pair of gnathopoda having the inferior margin 

 rounded ; palm oblique, convex, marginate*, armed with a central 

 short, blunt spine, and defined by two or three similar ones. Basa 

 of the three posterior paii'S of pereiopoda but slightly dilated. 

 Posterior pair of pleopoda very much longer than the preceding ; 

 rami subequal, lanceolate. 



Length of male 1^ inch, of female |- of an inch. 



Hab. Boston (J/. Lesueur) ; Massachusetts (Stlnijpson) ; Arctic 

 America {MS. B.M.). 



I am indebted to Mr. Stimpson for several specimens of this species, 

 which I believe is synonymous with Gammarus Pulex of Stimpson 

 and G. Locusta of Gould. Some Gammari in the Collection of the 

 Museum of the Royal CoUege of Surgeons, of which the habitat is 

 not mentioned, also appear to belong to this species, — the only dif- 

 ference consisting in the shorter length of the rami of the posterior pair 

 of pleopoda. The tj-pe from which the figure is draAvn is preserved 

 in the Museum of the Jardin des Plantes. 



13. Gammarus Redmanni. (Plate XXXVII. fig. 9.) 



Gammarus Redmanni, Leach, MS. B. M. 



Gammarus ornatus, White, Cat. Crust. B. 31. 1847 (not Edwards). 



This species resembles Gammarus ornatus, but microscopic observa- 

 tion of the gnathopoda exhibits a distinction. The first parr of 

 gnathopoda have the propodos ovate ; palm oblique, waving, mar- 

 ginate, armed near the centre with a short obtuse spine and a fas- 

 ciculus of hairs, and defined by several blunt spines, margination 

 convex, perpendicularly finely striated. The second paii' of gna- 



* The term " marginate " refers to a peculiar margin or thin cutting edge tliat 

 is found on the palm in some species, the form and appearance of which are liable 

 to variation. It will be best understood h\ a reference to the Plate. 



