232 
INDEX. 
Anterior margin , 10. 
Aplexa hypnorum, 203. 
Arion ater, 69 ; parasites on, 70 ; internal organs of, ib. 
- hortensis, 71 ; jaw of, ib .; phosphorescent eggs of, ib. 
Assiminia Grayana, 63 ; teeth of, ib. 
Atax ypsilophora, mite of the Swan mussel, 32. 
Auriculid^e (family), 177. 
Avicula margaritifera, pearls of, 28. 
Azeca tridens, 152. 
B. 
Balea perversa, 164. 
Bithinia Leachii, 57., 
-tentaculata, 56. 
Bivalves, parts of shell of, 10-13 ; composition and structure 
of shell of, 11; mantle of, 13 ; digestive organs of, 14 ; 
circulatory apparatus of, 15 ; respiratory organs of, ib. ; 
nervous system of, 17 ; organs of sense of, ib. ; muscular 
organs of, ib .; reproduction of, 18 ; food of, 19 ; col¬ 
lecting, ib . 
Branchial opening in bivalves, 14. 
Breadth of shell, 11. 
Bubble snails, 201. 
Bulimus genus, characters and species of, 146. 
- acutus, 147. 
- montanus, 148. 
-- obscurus, 149. 
Byssus y nature of, 21. 
C. 
Caddis-worm case like Yalvata piscinalis, 59. 
Cardinal teeth , 12. 
Carychium minimum, 177. 
- exiguum, 178. 
Chrysalis snails, 152. 
Circulatory system of bivalves, 15 ; in univalves, 52. 
