Mr. C. Spence Bate on British Edriophthalmous Crustacea. 137 



Tribe II. Natatoria. 



Mode of progression is by swiramiDg. Cannot leap or walk 

 when out of the water. 



Family II. GammaridaB. 



Body compressed. Legs long and slender. Posterior pleo- 

 poda well developed, the last being generally the longest. 



Subfamily I. STEGOCEPHALroES. 

 Antennae subequal. Coxse of the four anterior legs immensely 

 developed. 



Genus 1. Montagua (mihi). 



Upper antenna without secondary appendage. Mandibles 

 non-palpigerous. Hands of both gnathopoda subcheliform. Pos- 

 terior pleopoda single-branched. Telson entire. 



1. M, monoculoides (Montagu). Second joint of the peduncle 



of the upper antenna shorter than the first. Palm obhque, 

 occupying only half the length of the hand. 



S. Coast of Devon, Montagu {Linn, Trans, vol. xi.). Plymouth, 

 Howard Stewart, Esq,, C. S. B, 



2. M. marina (mihi). Palm nearly the whole length of the infe- 



rior side of the hand. 



Macdujff, Mr, Gregor, Banff, Mr, Edwards* Plymouth, from 

 trawlers, C, S. B, 



3. M. Alderii (mihi). Hand square, furnished with a small 



thumb ; palm denticulated. 

 Coast of Northumberland, /. Alder, Esq, 



4. M. pollexiana (mihi). Hand of second gnathopod furnished 



with a large thumb, which is formed by a deep cleft in the 

 palm. 

 St, Ives, G. Barlee, Esq. 



Genus 2. Danaia (mihi). 



First pair of gnathopoda simple ; last pair of pleopoda with 

 a single stylet. 



1. D. duhia (mihi). Coxse of the second, third and fourth 

 pairs of legs denticulated at the margin. 



Subfamily 11. LYSIANASSIDES. 



Upper antenna short, pyriform. Second gnathopod long, 

 feeble, and obsoletely subcheliform. 



