536 GEOGRAPHICAL ZOOLOGY. [PART iv. 



FAMILY 14. VENERID.E, (10 Genera, 600 Species.) 



DISTRIBUTION. Universal. Lucinopsis is confined to the 

 North Atlantic ; Glauconeza to the mouths of rivers in the Orien- 

 tal region ; Meroe and Trigona to warm seas. There are about 

 350 fossil species, ranging back to the Oolitic period. 



FAMILY 15. MACTRID^E. (5 Genera, 147 Species.) 



DISTRIBUTION. All seas, but more abundant in the Tropics. 

 Gnathodon is found in the Gulf of Mexico ; Anatinella in the 

 Oriental region. There are about 60 fossil species, ranging back 

 to the Carboniferous period. 



FAMILY 16. TELLINID^E. (11 Genera, 560 Species.) 



DISTRIBUTION. All seas ; most abundant in the Tropics. 

 Galatea is confined to African rivers. There are about 60 fossil 

 species, mostly Tertiary, but ranging back to the Carboniferous 

 period. 



FAMILY 17. SOLENID.E. (3 Genera, 63 Species.) m 



DISTRIBUTION. All Temperate and Tropical seas. There are 

 80 fossil species which range back to the Carboniferous epoch. 



FAMILY 18 MYACID^E. (6 Genera, 121 Species.) 



DISTRIBUTION. All seas. Panopcea inhabits both North and 

 South Temperate seas ; Glycimeris, Arctic seas. There are near 

 350 fossil species, ranging back to the Lower Oolite formation. 



FAMILY 19. AN ATINID^E. (8 Genera, 246 Species.) 



DISTRIBUTION. All seas. Pholadomya is from Tropical Africa ; 

 Myadora from the Western Pacific ; Myochama and Chamostrcea 

 are Australian. There are about 400 fossil species, ranging back 

 to the Lower Silurian formation. 



