Note on cases of representative shells that are not clearly either varieties or species.
Note on cases of representative shells that are not clearly either varieties or species.
Proportion of molluscan species to genera in various periods. The difficulty of determining species increases with the number of species per genus. Identifying species within a genus is most difficult in that period in which the genus shows its greatest development.
SPW and Waterhouse agree on island faunas; gives Australia and Tasmania as examples. The "stream of migration" from Asia to Tasmania.
Looks forward eagerly to the publication of CD’s "specific" researches.
Invites CD to send his memoranda [on Manual of Mollusca].
Has reduced 20 Cyrena species to geographical varieties of one species, Cyrena fluminalis. Hooker is reducing Indian flora at the rate of 19 to 1.
Recommends W. H. Harvey’s Seaside book [1849] and Charles Pickering’s Races of man [1850].
Lists Lusitanian shells with wide ranges beyond that geographical province.
Antiquity and elevation of land mass is more important than latitude for the distribution of shells.
Points out some errata in the Origin.
Discusses the factors producing the shape of the cells of the honeycomb.
Reports case of two varieties of musk-rat that behave very differently but are, according to Waterhouse, the same.
Has been writing a notice of H. W. Bates’s "capital book" [Naturalist on the river Amazons (1863)].
P. M. Duncan’s coral paper [J. Geol. Soc. Lond. 29 (1863): 406–58] strengthens SPW’s belief in the general diffusion of marine forms westward in the course of time.