72 CEYLON PEARL OYSTER REPORT. 



Parapenseus acclivis, Rathbun. 



Parapenaeus acclivis, Rathbun, ' Proc. U.S. Nat. Mus.,' vol. xxvi., p. 41, 1902. 

 Localities : Pearl banks, Gulf of Mauaar (Station III.), 1 specimen ; Trincomalee 

 (Station XX.), 1 specimen; south of Galle (Station XXXIX.), 1 specimen; Aripu 

 Reef (Station LXIV.), 1 specimen. 



The 3rd maxillipeds do not extend as far as the ends of the antennal scales, but 

 they are longer than those of Parapenceus mogiensis. The antennal scale is slightly 

 shorter than the antennular peduncle. 

 Dimensions of two females : 



Total length 88 millims., 80 millims. 



Length of rostrum and carapace .... 29 ,, 26 ,, 

 Lateral length of carapace 25 ,, 21 ,, 



Rostral formula ^ ^ . 







General distribution : Japan, Ceylon. 



Parapenaeus gallensis, n. sp. Plate I., fig. 3. 



Locality : South of Galle (Station XXXIX.), many specimens. 



This species is of the velutinus type, and possesses certain characters which 

 distinguish it from Dana's species and also from the species formed by 

 Miss Rathbun. 



In the form of the rostrum this sjaecies resembles somewhat closely P. dalei. The 

 length of the rostrum, however, is slightly shorter than in the latter species. In 

 typical specimens the rostrum reaches to the end of the 1st segment of the antennular 

 peduncle. In P. dalei the rostrum reaches to the middle of the 2nd segment. The 

 rostrum in P. gallensis is generally less toothed than in P. dalei, having a formula of 



^ '- . The anterior tooth is much smaller than the others, and in some cases is 



hardly perceptible. But in the form of the petasma and thelycum it differs distinctly 

 from P. dalei, and approaches nearer to P. akayebi, showing, however, distinct 

 differences from the latter species. The rostrum is much shorter than in P. akayebi 

 and has fewer teeth. The left branch of the petasma is much more delicate and 

 slightly longer than the right branch, and ends in a few small denticles, which, 

 however, are only observed when the petasma is examined under a microscope. The 

 antennal scale reaches as far forward as the extremity of the antennular peduncle. 

 The 3rd maxillipeds are slightly longer than those of the three previous species, 

 reaching almost to the end of the antennal scale. There is a pair of well-developed 



to the velviinus group, and I think Miss Rathbun is justified in separating from the old species certain 

 forms possessing various definite and distinctive characters. But it is doubtful whether these characters 

 are of sufficient importance to warrant the formation of new species, and I am not sure whether their 

 separation from Farapenmus velutinus merely as new varieties would not have been preferable. 



