24 INVEETEBRATB ANIMALS. 



Group 69.— Family MACTRID^,iw,axT/5«,a kneeding-trough. 

 Estimated number of species : recent, 188 ; British, 8 ; 

 fossil, 40, chiefly Tertiary. 



H Mactra, Liitraria, Harvella, Raeta, Lahiosa, 

 Anatinella, cC-c. 



Upper Com'partment. 



Interior of lAitraria, coloured to shew the pallial 

 sinus. 



Group 70. — Family ANATINID^, and allies, anatinus, 

 pertaining to the duck. Estimated number of species : 

 recent, 190 ; British, 17 ; fossil, 350. Devonian, &c. 

 IT Thracia, Myochama, Corhula, Periploma, Pan- 

 dora, d-c. PJioladomya, extremely rare in a 

 recent state, is a magnificent genus of 150 

 species as seen in its fossil representatives 

 from the Lias, &c. 



Group 71.— Family SOLENID^ and allies. crwX^v, a 

 gutter-tile. Razor-shells. Estimated number of species : 

 recent, 24 ; British, 5 ; fossil, 60. Eocene, &c. 



H Mya,Pano2)(sa,Novacidina, cC-c. Saxicava Angasi. 



Group 72.— Family PHOLADID^ and others. <f;«;A£/a, 

 living in holes. Estimated number of species : recent, 

 131 ; British, 14 ; fossil, 60. Eocene, &c. 



H Clavagella, BrecMtcs^Aspergillum, Pholadidca, 

 Parapliolas. The true bivalve shell of Asper- 

 gillum, not larger than a Laburnum seed, may 

 be seen on the tube. 



Upper Compartment. 



The tube of Ku2)hus giganteus. Specimens of wood 

 perforated by Teredo, often called the Ship- 

 worm, shewing the destructive character of the 

 borings made by this animal. 



