[234] Science, vii. p. 175.
[235] Hist. Nat. ix. 82.
[236] De re rustica, iii. 14.
[237] Epistles, i. 15.
[238] Hor. Sat. II., iv. 58, tr. Conington.
[239] Roberts, Zoologist, 1885, p. 425.
[240] Hist. Nat. xxx. 15, 19.
[241] Science Gossip, 1891, p. 166.
[242] Jeffreys, Brit. Conch. iii. p. 355.
[243] W. Clark, Mag. Nat. Hist. xvi. p. 466.