Zoological Society. 217 



** Upper scar of dorsal valves large; two lower scars smaller, far be- 

 hind the upper one. Shell oblong, transverse. iExiGJiA, Koch. 



16. Anomia ^nigmatica. 



Shell elongate, transverse, oblong;, purple or j-ellowish, with a pur- 

 plish di:jk ; apex acute, considerably within the dorsal edge. 



The upper scar large, suborbicular, subcentral ; lower scars 2, much 

 more posterior, small, equal-sized, and nearly confluent. 



Tellina senigmatica, Chemn. Conch, xi. t.'l99. f. 1949, 1950. 



Anomia rosea, Gra^J, Ann. Philos. 1825, 5. 



Anomia oenigmatica, Alton in JViegmann Arch. 1837, Verz. 21 ; 

 Reeve, Nomen. Conch. 



Hab. Indian Ocean. 



Var. 1. Elongate, purplish brown, smooth, flat. Chemn. I. c. 

 f. 1949, 1950. 



Hab. Indian Ocean, on the surface of flat wooden piles, &c. 



Var. 2. Like former, but more elongated, and the sides folded 

 together. 



iVnomia naviformis, Jonas ; fide Mus. Cuming. 

 ^Enigma, sp. Koch ; fide Mus. Cuming. 

 Hab. Manilla. Mus. Cuming. 



Var. 3. Flat, smooth ; like Var. 1, but yellow, with a dark purple- 

 brown transverse ray. 



Hab. Phihppines. Mus. Cuming. 



Var. 4. Flat, purple ; like Var. 1, but often more ovate, and with a 

 few radiating ribs, ending in projections, making the edge sinuous. 



Hab. Singapore ; on piles of wood forming the wharves. Borneo. 

 Mus. Cuming. 



*** Two upper scars small ; lower one large. Shell suborbicular ; 

 sinus small. Patro. 



17. Anomia elyros. 



White, lamellar, closely radiately striated. 



The disk of the upper valve with three separate subcircular scars ; 

 the two upper scars small, subequal, one under the other ; the lower 

 one large, nearly circular, subcentral. Notch in lower valve very 

 small. Plug small, elongate, subcylindrical ; the notch small, with 

 reflexed edges. 



Hab. Port Essington ; Earl of Derby. Depuch Island ; Capt. Sir 

 Everard Home, Bart. British Museum. 



Var. 1.? Shell very thin. Mus. Cuming. 



Var. 2. Very thick ; disk white, very thick. Mus. Cuming. 



The small size of the upper scars in this species probably depends 

 on the small size and elongated form of the plug. The other species, 

 M'hich have the upper scar the largest, have at the same time a larger 

 notch and a broader plug. 



II. Placunanomia. 



Upper or dorsal valve with two subcentral muscular scars ; the 

 upper scar radiately veined. Byssal notch distinct, converted into a 

 Ann. Sf Mag. N. Hist. Ser. 2. Vol. vi. 15 



