SOME BRACKISH- WATER AMPHIPODA. 665 



Perceopods 1 and 2 stoutly built ; the posterior margin of the 

 2nd joint and both margins of the 4th are fringed with long fine 

 setsB in the male, but carry only a few setae at intervals in the 

 female. The finger has the glandular aperture opening at 

 the tip. 



The hinder permopods are alike in both sexes. The 5th is 

 long and slender, about twice the length of the 3rd. The fingers 

 of perreopods 3 and 4 are strongly i-ecurved, that of perfeopod 5 

 falciform. The posterior margin of the 3rd is furnished with a 

 few simple setae, that of the 4th with plumose setai, while both 

 margins of the 5th are densely fringed with long and short 

 plumose setae ; the 6th joint of this pera?opod cairies two or three 

 clusters of remarkably long setae posteriorly. 



The incubatory lamellae are long, narrow, and fringed with 

 very long hairs, that of peraeopod 3 almost equals the peraeopod 

 in length. 



Telson the same in both sexes, about twice as broad as long, 

 the apex obtusely truncate ; a pair of mobile setae inset on each 

 side near the base. 



EXPLANATION OF THE PLATES. 

 Plate LXXIII. 



Fig. 1. Head of Gammariis zaddachi, sp. n., j-oung female, 9 mm. Eremerhaven. 

 The clusters of hairs are much denser in the males and in the older 

 females. X 42. 



2. Hands of gnathopods 1 and 2, G. zaddaclii, large male, 17 mm. Rauschen. 



X20. 



3. Hands of „ „ O. locusta, large male, 17 mm. Plj'mouth 



Sound. X 20. 



4. Gnathopod 1. Young female. Eremerhaven. G. saddachi. X 42. 



5. „ 2. „ „ „ „ X 42. 



6. Perasopod 1. „ „ „ „ X 42. 



7. „ 2. „ „ „ „ X42. 



8. „ 3. „ „ „ „ X 42. 



Plate LXXIV. 



Fig. 9. Pera;opod4. Young female, 9 mm. Eremerhaven. G. zaddachi, s^.\\. X 42. 



10. „ 5. „ „ „ „ „ „ X 42. 



11. Uropod 3. „ ,, „ „ „ " . X ^^• 



12. Diagrammatic dorsal view of pleon segments 4-6 and telson, showing the 



arrangement of the spine clusters ; in the males and older females, par- 

 ticularly in the freshwater form, these clusters are always accompanied by 

 long fine hairs. Young female, 9 mm. X 42. 



13. Antenna 1. Female. Corop/iww ZacMs^re VanhoflFen. Eremerhaven. X 42. 



14. „ ■ 2. „ „ „ „ „ X 42. 



15. Gnathopod 1. Male. „ „ „ ,, X 58. 



16. Finger and palm, gnathopod 1. Male. CoropJihcm lactistre Vanhoff'en. 



liremerhaven. X 145. 



17. Gnathopod 2. Male. Co?'ojj/«m)« ZwcMSifre Vanhoffen. Eremerhaven. X 58. 



Phoc. Zool. Soc— 1912, No. XLIY. 44 



