Xll LIrtT OB^ ILLUSTRATIONS. 



The moatli-tul)e, mandibles, and second niaxillse of a male chalimus of Alehion 



glaher «>3 



The lirst and .second maxillipeds of a chalimus of Alebion glaher 693 



The firpt and second swimming legs of a chalimus of Alebion glaher 694 



The third swimming leg of a chalimus of Alebion glaber 694 



A chalimus of Alebion glaher just ready to molt into the adult stage, showing the 



fourth segment separated and the fourth legs already formed 695 



The second antenna of an adult male of Alebion glaber 695 



The mouth-tube and second maxillae of an adult male of Alebion glaber 696 



The dorsal surface of a male Dgsgamus arlommas, showing areas and segments: 

 ((, anterior; m, median, and p, posterior transverse grooves; p. 1, j>- ~, and 



■p. 3, lateral lobes of the head, first and second thorax segments, respectively. 715 



PLATES. 



Facing 

 page. 



1. Schizopod crustaceans 54 



2. Schizopod crustaceans 54 



3. North American urocoptid moUusks 160 



4. North American urocoptid moUusks 160 



5. Mexican urocoptid mollusks 160 



6. North American digger wasps 424 



7. North American digger wasps 424 



8. North American digger wasps 424 



9. North American digger wasps 424 



10. North American digger wasps 424 



11. Orchestia costaricana 504 



12. Skeleton of Merycoidodon gracilis 514 



13. Skulls of slow lemurs 538 



14. Skulls of great ant-eaters 572 



15. The male and female of Trebius e.vilis and the female of Trebius (enuifur- 



calns 720 



16. The male and female of Trebius caudatus 720 



17. The female of Gloiopotefi ornaius 720 



18. The male and female of Alebion gracilis 720 



19. The male and female of Alebion glaber 720 



20. The male of Dysgamus ariommus and the male and female of Dissonus 



spinifer 720 



