372 CEYLON PEARL OYSTER REPORT. 



T should recognise a single species within which are (I) a group including specimens 

 figured by A. MILNE-EDWARDS, MIERS' five X. depressus specimens from Cape Howe, 

 and CALMAN'S male from Murray Island. This I name var. depress***. (2) A group 

 including ALCOOK'S two female examples from Ceylon and Andamans (A. Invest., 

 pi. xxxiii., fig. 3), and the present specimen, also a female. This group is inter- 

 mediate between (1) and (3). I name it var. alcocki. (3) WHITE'S female "type"- 

 specimen figured by MTERS, which stands alone. It is characterised among other ways 

 by having its gastric tubercle transversely divided. This I name var. tuberculatus. 



Huenia proteus, DE HA AN, 1837 A.I, p. 195. 



Localities : Aripu coral reef, two specimens (g, m) ; Chilaw Paar, one specimen (a) ; 

 Cheval Paar, Gulf of Manaar, nine specimens (h, c, d, Z>, i, I, n, o, &) ; Jokkenpiddi, 

 three specimens (c,f,j) ; Navakaddu Paar, one specimen (p). (o and p adult.) 

 Description: Males. (&;. (/). (*). (ri). (o). (p). 



C.I 12*50 14-00 1475 1875 20'50 2475 



Rl.-=-C.l 0-36 0-43 0-41 0'40 0'45 0'41 



Ch.L-rC.l. . . . 0-82 1-14 1-05 



Propus 1.-5-C.1. . . 0-36 0'50 0'46 



Females, yg. (a), ov. (I), yg. (c). ov. (d). ov. (e). ov .(/) ov. (g). ad. (h). ov. (i) ov. (/"). 



C.I. . . . 13-25 14-25 14-50 14'50 16'50 20'00 20'50 21'25 21'25 21'50 



R.1.-S-C.1. . 0-32 0-32 0-33 0'29 0'32 0'32 0'33 0'31 0'33 0'30 



Ch.L-rC.l. . 0-81 079 077 076 079 079 078 0'82 



The kind of alga carried by the animal varies. In (a), which is described by a 

 label as a " green crab tinted similarly to the green alga on which it was found," it is 

 a large piece of foliaceous Halimeda, while in (e) it is a branch of filamentous alga. 



The hepatic lobes of the female may be horizontal as in (e), or they may curve 

 considerably upward as in (A). Between these limits the other specimens may be 

 arranged in a good connecting series. 



The border of the hepatic lobe of the female is in some entire, in others irregular. 



In all the males there is a pair of small transversely placed tubercles in front of the 

 anterior median elevation. This is present also in ovigerous female (/'), and a trace 

 appears in ovigerous female (i). 



The carapace-outline of all the males except (p) agrees with ADAMS and WHITE'S 

 fig. 4 (' " Samarang" Crust./ pi. iv., fig. 4). Specimen (p), which is the largest male 

 in the collection, more resembles DE HAAN'S fig. 5 of the larger form (Crust, in ' Faun. 

 Japon.,' pi. xxiii., fig. 5), but the anterior border of the epibranchial lobe slopes 

 obliquely backwards, and in the same crab the upper border of the hand and wrist is 

 strongly carinate, and on the upper, under, and outer surfaces of the arm are a few 

 distinct short blunt spines. 



In the two largest males Ch.l. -=-0.1. is rather more than 1, instead of rather less as 



