208 MTOCHAMA. 



species of Mya are known. They belong to the Northern 

 Hemisphere. M. truncata. PL iii. fig. 71. 



MTCETOPODA or MTCETOPUS. D'Orb. Fam. Nayades, 

 Lam. Bescr. Shell elongated, soleniform, inequivalve, inequi- 

 lateral, gaping anteriorly ; muscular impressions very complex. 

 —06s. These shells are said to terebrate like Pholas. M; 

 solenoides. PL viii. fig. 151i 



MYAB.IA. Lam, A family belonging to Lamarck's order Con- 

 chifera Dimyaria. Containing the following genera : 



1. Anatina. Ligament in a spoon-shaped prominence on 



the hinge of each valve, shell thin. Fig. 69. 



2. Mya. Spoon-shaped prominence in one valve ; shell thiek.- 



Eig. 71. 



3. Anatinella. a spoon-shaped process in toth valves. 



Eig. 70. 



4. Ltonsia. An internal bony appendage on the hinge. 



Eig. 491, 492. 



5. Mtoohama. Elat valve attached, a bony appendage on 



the hinge. Eig. 73. 



6. CLEiDOTHiEEUS. Deep valve attached, a bony appendage. 



Eig. 75, 76. 



7. Cumin GiA. Ligamentary pit in both valves, spoon-shaped. 



Eig. 87. 



MTOCHAMA. Stutch. (Myc and Chama.) Fam. Myaria, Lam. 

 — Bescr. Inequivalve, irregular, attached, subequHateral; attached 

 valve flat, with two marginal, diverging teeth, and one end of a 

 little testaceous appendage fixed between them by a horny car- 



• tilage; free valve convex, with umbo incurved and two very 

 minute, diverging teeth, between which the other end of the 

 testaceous appendage is placed ; external surface of both valves 

 conforming to the grooves or undulations of the shell to which 

 the specimen is attached ; muscular impressions two in each 

 valve ; palleal impressions with a short sinus. — Obs. This new 

 genus, of which only one species is known, the M. anomoides 

 from New South "Wales, differs from Anomia and Anatina in 

 being attached by the surface of one of the valves, from which 



