242 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.42. 



Three females and two males, all excellently preserved, were 

 obtained from the gills of Polynemus tetradactylus at Batavia, Java. 

 One female has been numbered 42303, U.S.N.M., and becomes the 

 type of the new species. The other two females and the two males have 

 received the catalogue number 42326, U.S.N.M., and become cotypes. 

 In addition to the spiny processes this species is further distin- 

 guished by the strong narrowing of the cephalothorax and the widen- 

 ing of the fourth dorsal plate. All the specimens of both sexes were 

 found fastened to the outside of the gill filaments, close to the upper 

 end of the gill arch. 



EXPLANATION OF PLATES. 



Plate 30. 

 Male and female of Argulus ingens, new species. 



Fig. 1. Dorsal view of male. 



2. First and second antenna of female. 



3. Maxilliped. 



4. Bases of the four pairs of swimming legs of the male, showing accessory 



sexual organs. 



5. Respiratory areas. 



6. Three of the supporting rods in the edge of the sucking disk. 



Plate 31. 

 Female of Argulus ingens, new species, and male of Achtheinus pinguis, new species. 



Fig. 7. Dorsal view of female of Argulus ingens. 



8. Dorsal view of male of Achtheinus pinguis. 



9. Mouth tube and first maxillae of the same. 

 10. Maxilliped. 



11-14. First, second, third, and fourth swimming legs. 



Plate 32. 



Females of Achtheinus pinguis, new species, and Caligus phipsoni Bassett-Smith. 



Fig. 15. Dorsal view of female of Achtheinus pinguis. 

 16. MaxilUped of same. 

 17-20. First, second, third, and fourth swimming legs. 



21. Ventral view of genital segment and abdomen, showing the cement glands 



and nidimentary fifth and sixth legs. 



22. Dorsal view of female of Caligus phipsoni. 



Plate 33. 

 Females of Caligus phipsoni and Parapelalus hirsutu^ (Bassett-Smith). 



Fig. 23. Second antenna and mouth-parts of Caligus phipsoni. 



24. First swimming leg. 



25. Furca. 



26 and 27. Third and fourth swimming legs. 



28. Dorsal view of female of Parapetalus hirsutus. 



29. Second antenna, maxillary hook, mouth-tube, and maxilla. 



30. Maxilliped. 



31. Furca. 



32-35. First, second, third, and fourth swimming legs. 



