364 CEYLON PEARL OYSTER REPORT. 



Philyra adamsi, Bell, 1855 ('Trans. Linn. Soc.,' xxi., p. 301) Plate I., fig. 1. 



Localities : Pearl banks, Gulf of Manaar, two specimens ; coral reefs, Gulf of 



Manaar, four specimens, including (b) ; Galle, seven specimens, including (). 



n 4- n i n i n 1 n\ 1 r- 1 H1 - ( u PP er Fixed fin ger (inner 



Description: C.I. C.b. -i-C.l. Ch.l. -=-C.l. . . \" . , , 1. 



border) -;- C.l. border) -j- C.l. 



I have compared the specimens with Bell's " type " preserved in the British 

 Museum, and they agree well with it. 



Bell's figure gives an inadequate, and in some respects erroneous, idea of his 

 specimen. Henderson amends Bell's description (H., p. 400), but omits reference 

 to any hepatic facet, the presumed absence of which has been lately emphasised by 

 Nobili (N, p. 104). In re-figuring Bell's specimen I emphasise (1) general shape 

 of front ; (2) presence of a small median frontal tooth, at lower level than rest of 

 front ; (3) details of hepatic facet ; (4) two tubercles on hand at base of fixed 

 finger ; (5) proportions of buccal cavern ; (6) exognath of external maxilliped. 



Remarks : Alcock omits this species from his key, observing that it appears to 

 him to be rather a Pseudophilyra. It is indeed intermediate in many ways, e.g. : (l) 

 production of front ; (2) general proportions of buccal cavern ; (3) shape of exognath 

 of external maxilliped. But in all these particulars it bears considerable resemblance 

 to Philyra platychira and to Ph. granigera, Nobili, 1906 (N., p. 102, pi. vi., fig. 30), 

 both of which it further resembles in the presence of the hepatic facet and of the 

 longitudinal grooves of the carapace (the latter more as P. granigera than P. platychira). 

 It must be placed in the same genus with these, and all three fall under section 1.2.1 

 of Alcock's key of Philyra. 



Ph. adamsi is at once distinguished from Ph. platychira by the entire sub-orbital 

 border of the endostome and by the characters of hand and fingers. 



It is more closely allied to Philyra granigera than Nobili imagined, since it has in 

 reality a hepatic facet. It differs from Ph. granigera in possessing: (1) line of 

 granules on upper border of inner surface of hand and wrist ; (2) the distinct granule 

 on upper surface of hand proximal to base of fixed finger (tendency for a second, less 

 distinct granule just distal to the distinct one) ; (3) the small median frontal tooth. 



Philyra globosa (Fabr.), 1787 A. 2, p. 243. 



Localities : Trincomalee, one specimen (immature male) ; Galle, two specimens 

 (adult females). 



Pseudophilyra tridentata, Miers, 1879 A. 2, p. 250. 

 Locality : Pearl banks, Gulf of Manaar, five specimens (a, b, c, d, e). 



