536 GEOGRAPHICAL ZOOLOGY. [part iv. 



Family 14.— VENEKID.E, (10 Genera, 600 Species.) 



Distribution. — Universal. Lucinopsis is confined to the 

 North Atlantic ; Olauconeza 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^. (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^. (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^. (3 Genera, 63 Species.) 



Distribution. — All Temperate and Tropical seas. There are 

 80 fossil species which range back to the Carboniferous epoch. 



Family 18.— MYACID^. (6 Genera, 121 Species.) 



Distribution. — All seas. Panopma 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.— ANATINID^. (8 Genera, 246 Species.) 



Distribution. — All seas. Pholadomya is from Tropical Africa ; 

 Myadora from the Western Pacific ; Myochama and Chamostrma 

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

 to the Lower Silurian formation. 



