I 



Zoology. 137 



IV. Pedes tertii quartique subcbeliformes. 



1. Antennae sup. appendicular. Pedes tertii quar- 

 tique validi, articulo quarto dilatato instar palmse, 

 ungue couico, aculeate Pontoporeia* (Kroyer). 



SlJBFAM. II. GaMMARINjE. 



Antennae superiores ad basin tenues. Epimera sive grandia sive an- 

 gusta. Pedes 6 postici non prehensiles. 



I. Pedes subcheliformes nulli, secundis parvulis interdum exceptis. 



1. Antennae superiores appendicular. Alibrotus (M. Edw.). 



2. Antennas sup. non appendiculatse. Acanthonotus (Owen). 



II. Pedes primi subcheliformes, secundi non subcheliformes, reliqui 

 non prehensiles. 



1. Antenna? sup. appendicular. Leptoehirus\ (Zaddach). 



III. Pedes primi secundique subcheliformes, reliqui non prehensiles. 



A. Antenna secundce subtus primas insitce. 



* Digiti toti uni-articulatL 

 a. Pedes sex postici similes. 



1. Atftennaa sup. appendicular. Gammarus\ (Fabr.). 



2. Antennae sup. non appendicular. Amphithoe^ (Leach). 



* Tids. iv, 152. "Pedes primi et secundi pans perbreves, robusti ; illi manu lata- 

 instruct i ungue vero breviore; hi manu carentes ungueque prsediti nulimentari. 

 Pedes tertii quartique paris longiores, validi, su bcl i el i formes, articulo quarto dilatato 

 palmam efficients, ungue armati conico, aculeato. Pedes quinti et sex ti paris re- 

 curyi, articulo primo parum modo dilatato ungue armati perpusillo. Pedes septimi 

 pans recurvi, articulo primo permagno, clypeiformi; articulo sexto vel ungue rudi- 

 nientari. Epimera magna." 



t Sjfc- Crust. Pruss. Prodromus, 1844. Tliis genus is stated to be allied to Am- 

 pliithoe. 



X From the genus Ganmiarus. Leach separates: — 

 b il kra (Edinb. Encyc, vii, 403 ; Trans. Linn. Soc, xi, 359.) Manus secunda? valde 

 Btfaqm, majore bene cheliformi. 



Melita (Edinb. Encve , vii, 403.) Digitus pedum secundi paris in latus manus 

 claudens. 



The Amathia of Ratlike (Fauna der Kiyni, Mem. Acad Imp. St. Petersburg, iii, 

 1837, p. 201, and Beit, zur Fauna Norwegens, Act, Leop., xx Bd.) includes those 

 Gammari which have the superior antennae shortest— apparently an unimportant 

 distinction. 



8 Amphithoe includes the T>emmi*e and Pherusa of Leach. Eumiw* of Kroyer 

 (Tids., N. R., i, 501,) i somewhat peculiar in the form of the hands, but the gradations 

 ^ong the species are such that the character is not sufficient even for a subgenus. 



Kroyer's Microcheleg (Tids., N. R. f vol. h,) is also near Amphithoe. The principal 

 P?int of difference mentioned is the absence of the molar prominence from the man- 

 dl ble. The small hands to which the name alludes is common to many Amphithoes, 

 especially females. 



The Ipkimedia of Rathke (Beit, zur Fauna Norwegens, p. 85; Act. Leop., 1*<1. xx) 

 appears to differ little from Amphithoe. The superior antennae are shorter than the 

 ^rior, and this characterizes generally the species from the higher latitudes. Aeon- 

 thosoma of Owen (Ross's 2d voyage to the north in 1829-1833, Append p. xci) has 

 the si me characters. The description of Iphimedia by Rathke is as follows— p. 89. 



Anteim* superiores inferioribus breviores ; illarum peduneulus e trims, hi 

 quutuor articulis, compositus: omnium rla-ellum tenue, multiartieuiatum. . 

 secundi paris marnbus simplicibus, primi pans, illis minores, chehs instruct!, quorum 

 pjjex ex uno tantum articulo constat, Reliqui pedes ns Gammarorum similes, 

 edes spurii in duos ramos plus minusve complanatos divisi." 



Second Series, Vol VIII, No. 22.— July, 1849. 18 



p. 89. 

 arum e 



Pedes 



