Gammaridea 



716 I 

 19.! 



20 < 



21 



22 < 



23 



24 



Mandible and maxillae 1 and 2 developed 7, 



Mandible weak, maxillae 1 and 2 obsolete 8. 



Uropod 3 not biramous — 11. 



Uropod 3 biramous — 14. 



Mandible with palp — 12. 



Mandible without palp — 13. 



Mandible, 3d Joint of palp very short . . 9. 



Mandible, 3d Joint of palp not short. . . 10. 



Maxillipeds (Fig. 51) with outer plate obsolete 11, 



Maxillipeds with outer plate developed . . 12 



Mandible without palp 1-3. 



Mandible with palp — ■ 15. 



Maxillipeds (Fig. 54) with palp 2-jointed . 14. 



Maxillipeds with palp 4-jointed 15. 



Mandible (Fig. 56, 58, 60) with molar weak 



or wanting ; telson more or less divided — 17. 

 These characters not conibined — 19. 

 Maxillipeds (Fig.55),innerplate well developed 16. 



Fam. Leucothoidae . . p. 161 

 Farn. Anamlxidae . . . p. 170 



^ 



Fam. Metopidae . . . 

 Fam. Cressidae . . . 

 Fam. Stenothoidae . . 

 Fam. Phliantidae . . 

 Fam. Colomastigidae . 



Fam. Lafystiidae . . 

 Fam. Laphystiopsidae 



p. 171 '^ 



p.190 

 p. 192»^ 

 p.200 

 p. 206 



p. 208 «^ 



,p. 209 



Fam. Acanthonotozo- 



matidae p. 210 \f^ 



17. 



18 



Fam. Pardaliscidae 

 Fam. Liljeborgiidae 



p. 220 ^ 



p. 229 



p. 235 



Maxillipeds (Fig. 59), inner plate small — 18 

 Gnathopods 1 and 2 ("Fig. 57) simple . . 

 Gnathopods 1 and 2 strongly subchelate 

 Eyes*), when present, usually dorsal con- 



tiguous or confluent (Fig. 61, 62) — 20. 

 Eyes*), when present, lateral — 22. ' 

 Antenna 1 (Fig. 67) without accessory fl^gel- 



lum; mandible, 3d Joint of palp large; 



peraeopod 5 (Fig. 64) much longer than 



peraeopod 4; telson entire 19. Fam. Oedicerotidae 



Antenna 1 (Fig. 70) with accessory fiagellum ; 



mandible, 3d Joint of palp small; peraeo- 

 pod 5 not exceptionally longer than 



peraeopod 4; telson usually cleft**) — 21. 

 Peraeopods 1 and 2 with 4tli and 5tli joints 



dilated . 20. 



Peraeopods 1 and 2 with 4tli and 5tli joints 



not dilated 21. 



Side-plate 4 (Fig. 84) usually excavate behind; 



peraeopods 1 (Fig. 91) and 2 not glandulär ; 



telson (Fig. 81, 100) variable; animal 



usually not domicolous — 23. 

 Side-plate 4 usually not excavate behind; 



peraeopods 1 and 2 frequently glandulär; .j^,^ 



telson (Fig. 115, 118) entire; animal 



usually domicolous — • 31. 

 Mandible (Fig. 77) with palp — 24. 

 Mandible (Fig. 90) without palp — 30. 

 Telson entire — 25. 

 Telson cleft — 27. 

 Telson variable, usually cleft; antenna 1 



usually with accessory flagellum .... 30. Fam. Gammaridae . . . p. 364 



•^ A//= 



Fam. Synopiidae 

 Fam. Tironidae 



p.270 



p.273 ^ M^ 



^ ,lf 



*) In the case of blind species or exceptional genera like Ommatogammarus 

 the distinguishing characters under 20 and 21 will give assistance, and for the Gam- 

 marids of Lake Baikal the locality will be a guide. 



**) Except in Bruzelia (p. 274). 



