1906.] CRUSTACEA OF THE THIRD TANGANYIKA EXPEDITION. 205 



the characters of the Macrura seem to me to point in the direction 

 of some such explanation as that which has been suggested by 

 Mr. Boulenger in the case of the fishes, namely, that the forms 

 now inhabiting the lake are the result of divergent evolution and 

 specialisation during a very long period while the lake was quite 

 isolated. 



EXPLANATION OF PLATES XL-XIV. 



Plate XL 



Fig. 1. JPalcemon moorei (p. 188), second pei-asopod of female. Total length of body 

 27 mm. 1 a. Portion of same, further enlarged. 



2. Limnocaridina retiarius (p. 192), female. Cephalothorax from the side. 



3. „ „ female. Antennal scale. 



4. „ „ „ Perseopod of first paii', 



.5. „ ,, „ Perajopod of second pair. 



6. „ „ „ PeriEopod of fourth pair. 6 a. Dactylus 



of same, further enlarged. 



7. „ „ „ Perseopod of lifth pair. 7«. Dactylus of 



same, further enlarged. 7 h. Spines of 

 dactylus. 



8. „ „ „ Tail-fan. 



9. Limnocaridina parvula (p. 193), female. Cephalothorax from the side. 



10. „ „ female. Peraeopod of first pair. 



11. „ „ „ Perseopod of second pair. 



12. „ „ ,, Peraiopodof fourth pair. 12 a. Dactylus 



of same, further enlarged. 



13. „ „ ,. PerDsopod of fifth pair. 13 a. Dactylus 



of same, further enlarged. 



14. „ „ „ Tail-fan. 



Plate XII. 



Fig. 15. Limnocaridina similis (p. 195), female. Cephalothorax from the side. 



16. „ ,, female. Antennal scale. 



17. „ „ ,, Peraeopod of hi'st pair. 



18. „ „ „ Peraeo]3od of second pair. 



19. ,, „ ,, Perffiopod of third pair, dactylus. 



20. „ „ „ Peraeopod of fifth pair. 20 a. Dactylus 



of same, further enlarged. 



21. „ „ male. Perasopod of third' pair. 21a. Dactylus 



of same, further enlarged. 



22. „ „ female. Tail-fan. 



23. Limnocaridifia latipes (p. 196), female. Cephalothorax from the side. 



24. „ ,, female. Antennal scale. 



25. „ „ ,, Perajopod of first pair. 



26. „ „ „ Peraeopod of second pair. 



27. „ „ „ Peraeopod of fourth pair. 27 a. Dactylus 



of same, further enlarged. 



28. „ „ „ Peraeopod of fifth pair. 28 a. Dactylus 



of same, further enlarged. 



29. „ „ „ Tail-fan. 



30. Limnocaridina socius (p. 196), female. Cephalothorax from the side. 

 81. „ „ female. Antennal scale. 



32. „ „ ,, Pera3opod of first pair. 



33. „ „ „ Peraeopod of second pair. 



34. „ „ „ Perteopod of fourth pair. 34 a. Dactylus 



of same, further enlarged. 



35. „ „ male (smaller specimen). Dactylus of fourth pera;o- 



pod. 



36. „ „ female. Peraeopod of fifth pair. 30 a. Dactylus of 



same, further enlarged. 



37. „ „ „ Tail-fan. 



