LITERATURE OF THE SUBJECT. 
Besides the accounts relating to the Heteropoda which are given in the various 
manuals on Mollusca by Bang, Woodward, Philippi, H. and A. Adams, Chenu, Tryon, 
Fischer, and others, several more detailed narratives are to be found in the works of 
d’Orbigny, Souleyet, Huxley, Krohn, Leuckart, Gegenbaur, Macdonald, &c. 
A very excellent work upon this group of animals by Keferstein, which was published 
in Bronn’s Thierreich, 2 gives a detailed account of the knowledge of this subclass of 
Mollusca up to the year 1866. 
The work commences with an introductory chapter (pp. 809-813), containing (1) a 
historical account of the study of this group of animals ; (2) some observations upon the 
various names which have been applied to it ; and (3) a list of the principal works which 
treat upon the subject. 
The second chapter (pp. 814-835) enters very fully into the external structure and 
the internal anatomy; the third (pp. 835-838) is devoted to the history of the develop- 
ment of these animals ; the fourth (pp. 838-843) gives an account of the economy, their 
pelagic mode of life, the positions in which they swim and the food they subsist on. The 
fifth chapter (pp. 843-850) discusses the classification of the Heteropods, their natural 
position in the systematic arrangement of the Mollusca, gives succinctly the characters 
which distinguish the group, and concludes with diagnoses of the families and genera. 
The sixth and last chapter (pp. 851-852) treats upon the distribution of the species, both 
recent and fossil. 
Such being the scope of this work, it may in the main be consulted as a sound text- 
book upon this branch of Mollusca. It would therefore be of little use to reproduce in 
this Report a detailed account of the Heteropoda (as at one time I thought of doing) such 
as that set forth in Keferstein’s treatise; but several very important memoirs have been 
published since the production of that work which give further information respecting 
1 Die Klassen und Ordnungen des Thierreiehs, vol. iii. pt. ii. pp. 809-852, pis. 68-70. 
