270 CEYLON PEARL OYSTER REPORT. 



hairs. Anterior antennae 8-jointed, the proportional lengths of the joints being as 



follows : r * ,' ' ' .' r . The 4th joint bears a long thin filament. 

 11. 11. 5. 8. 3. o. 2. b. J & 



First pair of natatory legs of female same as in D. hirsuta ; the inner branch in male 

 has a remarkably long stout spine equalling in length the 1st joint, projecting from 

 the 2nd basal joint. The 2-jointed inner branch of 2nd pair in male has 3 thick more 

 or less curved spines at apex of 2nd joint. Outer joint of 5th pair in female about 

 equal in size to the 1st joint. In the male both joints are exceedingly small. 



Eighteen females and 13 males were found in the Muttuvaratu pearl oyster 

 washings. The chief distinguishing characters of this species are the inner joints of 

 1st and 2nd male natatory legs, and the 5th pair in the female. 



Dactylophusia hamiltoni, n. sp. Plate X., figs. 1 to 7. 



Length, female I'l millim. ; male unknown. 



Cephalothorax and abdomen each with 5 segments. 



Anterior antenna? 8-jointed, the proportional lengths of the joints being as 

 . 1. 2. 3. 4. 5. 6. 7. 8. 



f0ll WS: 12.T2. 10. 11.3.G. 4. 7. 



A long filament springs from the prolongation of the 4th joint. Outer branch of 

 posterior antenna? 3-jointed, a 2-jointed inner branch springing from the basal joint. 

 Second maxillipeds large ; the apical claw strong, blunt at end. Inner joint of 5th 

 pair of natatory legs subquadrate, about twice as long as broad. Abdomen long and 

 slender ; furcal rami quadrate, about twice as long as broad. 



One specimen only, a female, was found in the Muttuvaratu pearl oyster washings. 



The form of the 2nd maxillipeds, and 5th pair of natatory legs, and the abdomen, 

 are characteristic of this species, which we name after Colonel Hamilton, a former 

 inspector of the pearl banks. 



Dactylophusia robusta, 11. sp. Plate X., figs. 19 to 24. 



Length, female 0"G4 millim. ; male unknown. 



A small but moderately robust species with a very tumid cephalothoracic segment. 



Anterior antenna? 8-jointed. Joints long and narrow, with the exception of the 



1. 2. 3. 4. 5. G. 7. 8. 

 5th, which is very small ; the proportional lengths are : nn - -,_, 



J l i 14. 24. 12. 20. 4. 10. 7. 12. 



Posterior antennae, mandible, and maxilla similar to those of D. gracilicaudata > 

 2nd maxillipeds have the palm straight and the lower side rounded. Outer branches 

 of the 1st natatory legs much shorter than the inner blanches. The middle joint of 

 the outer branches longer than either the basal or apical joints ; 2nd, 3rd, and 

 4th legs resemble those of D. tisboides. The 5th pair have a large primary joint and 

 a moderately long and narrow secondary joint. The primary joint is furnished with 

 5 seta?, and the secondary with G seta?. Abdomen 4-jointed, about half as long as 



