COPEPODA. 275 



anterior antennae. Cleve has formed a genus Reticulina for the species R. aurivillii, 

 which is certainly a Peltidium, but it is not sufficiently well figured to enable us to 

 compare it with any of the foregoing species. 



Ilyopsyllus affinis, T. Scott. 



Appeared once between Port Said and Suez, and again in the Gulf of Manaar, also 

 at Kodramallai, north of Karativo, and 2|- miles south-south-west of Ohilavaturai. 



Porcellidiurn fimbriatum, Glaus Plate XII., figs. 1 to 10. 



Lenoth, female 0"7 millim. 



. . . -, i , , 1. 2. 3. 4. 5. 6. 



Anterior antennae 6-jomted ; proportional lengths ot joints : - 



A few specimens, all females, of this species, which appear to be identical with 

 Clalts' P. fimbriatum, were found in the washings from the Muttuvaratu pearl 

 oysters. The chief points that distinguish this species from the others are the 5th 

 feet, the abdomen, and the furcal rami. 



Porcellidiurn brevicaudatum, n. sp. Plate XII., figs. 11 to 14. 



Length, female 0"G7 millim. 



A . . . , , 1. 2. 3. 4. 5. 6. 



Anterior antennas G-iointed, as follows : 



J 13. 17. 12. 8. 4. 2. 



This species is easily distinguished from the others by its smooth carapace and 

 ciliated margins, the large 5th feet, the short abdomen, and the furcal rami. 



Six specimens, all females, were obtained from the Muttuvaratu pearl oyster 

 washings and from the general washings of Ceylon Invertebrates. 



Porcellidiurn acuticaudatum, n. sp. Plate XII. , figs. 15 to 18. 

 Length, female 0*6 millim. 

 Anterior antennas 6-jointed ; proportional lengths as follows : 



The chief features of this species are its moderately large 5th feet with rounded 

 apex, the small abdomen produced laterally on each side, and the acutely pointed 

 apex of the furcal rami. 



Three females of this distinct species were found in the washings from the 

 Muttuvaratu pearl oysters. 



Porcellidiurn ravanae, n. sp. Plate XII., figs. 19 to 22. 

 Lenoth female 0'6 millim. 



Anterior antennae 6-jointed ; proportional lengths as follows : * 



10. 18. 13. 8. 5. o. 



The distinguishing characters of this Porcellidiurn are the moderately wide 5th 



feet, which taper off to an acute point, the small abdomen, the posterior angles of 



which are not so much prolonged as in P. acuticaudatum, and the obliquely rounded 



2 n 2 



