ARTHROPODA 



291 



may usually be distinguished by the developement of their 

 olfactory hairs on the first antennae, by the absence of 



■'XIV-XIX 



Fig. 167. — Gammarus neglectus. Female tearing 'eggs seen in profile. 

 From Leuokart and Nitsohe, after G. 0. Sars. 



T. -VI. Cephalothorax. 

 VIE.-XIII. Free thoracic segments. 

 XIV. -XIX. The six abdominal segments. 



1. Anterior antennae. 



2. Posterior antennae. 



3. Mandibles. 



4. 1st maxillae. 



5. 2nd maxillae. 



6. Maxillipede. 

 7-13. Thoracic limbs. 



14-16. Three anterior abdominal limhs 

 for swimming. 



17-19. Three posterior abdominal limbs 

 for jumping. 



20. Heart with six pairs of ostia. 



21. Ovary. 



22. Hepatic diverticula. 



23. Posterior diverticula of the ali- 



mentary canal. 



24. Median dorsal diverticulum. 



25. Alimentary canal. 



26. Nervous system. 



27. Ova in egg pouch, formed from 



lamellae on the coxae of the 

 three anterior thoracic limbs. 



oostegites, and by the presence of strong prehensile hooks on 

 the anterior thoracic feet. 



Appendages of Amphipods. 



1. Antennules. 6. Maxillipedes (fused). 



2. Antennae. 7-13. Thoracic legs. 



3. Mandibles. 14-16. Abdominal legs (turned forward). 



4. 1st maxillae. 17-19. ,, „ (turned backward). 



5. 2nd ,, 



