372 ANATINIDiE. 



triangular pit between the teeth, furnished with a free, sickle- 

 shaped ossicle. Pallial impression sinuated posteriorly. 



Ex. M. brevis, Stutchbury, pi. 98, fig. 2, 2, a. 



The structure of the shell in My odor a resembles that of 

 Anatina, the outer cells being large and somewhat pris- 

 matic. The geographical distribution of the species extends 

 from the islands of the China Sea and the Philippines to 

 New Zealand and New South Wales. 



Species of Myodora. 



brevis, Stutchb. Pandoneformis, Stutchb. 



crassa, Stutchb. plana, Reeve. 



curvata, Reeve. striata, Desh. 



oblonga, Reeve. tincta, Reeve. 



ovata, Reeve. trigona, Reeve. 



Genus MYOCHAMA, Stutchbury. 



Siphons distinct, unequal, small, their orifices fringed ; a 

 minute fourth orifice close to the base of the branchial 

 siphon. 



Shell adherent, irregular, inequivalve, the right valve 

 flat, attached, the left valve free, convex, with radiating ribs 

 or grooves. Hinge composed of two diverging tooth-like 

 processes in each valve, with a triangular pit between them 

 for the internal cartilage, which is furnished with a mov- 

 able ossicle; ligament thin, external. Anterior muscular 

 impression curved, posterior rounded ; pallial line with a 

 short, broad sinus. 



Ex. M. anomioides, Stutchbury, pi. 98, fig. 3. Shell, 

 M. Stutchburyi, A. Adams, fig. 3, a, 3, b. Ossicle, M. 

 Stutchburyi, fig. 3, c. 



