224 AMVlIirODA NOKMALIA. 



prominent teeth, of which the dorsal uuo is shortest ; two next 

 segments armed at the tip with two prominent acute teeth. 

 " Length f^jths of an inch. 



" Ilah. (jeorgia." — Say. 



It is difficult, from the above description, to laiow to what genus 

 this species belongs. Certainly it does not belong to Oammarus. It 

 appears to be related to Fodocerus. 



41. Gammarus scissimanus. 



Gaiuniaius scissimanus, Costa, Rend, clella Reale Accad. dellc Scienze 

 di Napoli, 1853, p. 17(3. 



"Having the dorsal surface smooth, imarmed. Superior antenna3 

 one-fourth shorter than the body, flagellum scarcely shorter than 

 the peduncle ; inferior antennae much shorter than the superior, 

 flagellum a little longer than the last joint of the peduncle. First 

 pair of gnathopoda small ; second pair strong, having the propodos 

 with the palm a little oblique, sinuous, obtusely denticulated, 

 deeply cleft in the middle. Pleopoda terminating subequally. 



" Length 2|- lines. 



" Hah. Naples." — Costa. 



42. Gammarus punctatus. 



Gammarus punctatus, Costa, Rend, della Reale Accad. delle Scienze di 

 Napoli, 1853, p. 176. 



" Having the dorsal surface smooth, unarmed. Superior antennae 

 scarcely shorter than the body, flagellum nearly twice as long as 

 the peduncle ; inferior antennae much shorter and more slender, 

 with the peduncle a little shorter than the peduncle of the supe- 

 rior. Second pair of gnathopoda having the propodos large, elon- 

 gated, with the palm punctato-striated externally, internally chan- 

 nelled for the reception of the strong dactylos ; ductylos as long as 

 the palm, having the margin fretjuently barbed. 



" Length 3| lines. 



" Hob. Naples." — Costa. 



Costa says that it is nearly allied to GammareUa hrevicawdata. It 

 appears to me to be nearly allied to the genus MeJita. 



66. MEGAMCERA. 



Gammarus (Division a a), Edwards, Hist, des Crust, iii. p. 48. 

 Gammarus (Div. -t-2), Liljeborg, Of vers. Skand. Gamin. 1854, p. 452. 



Dorsal segments of the pleon without fasciculi of spines. Eyes 

 round. Superior antennae long : inferior about half the length of 



