Congratulations [on Mrs H’s delivery].

Balanus balanoides positively identified by CD.

Asks THH question on flow of glaciers after ice has been fractured and fragmented.

CD had to leave Royal Society lecture [joint paper by THH and J. Tyndall, "On the structure and motions of glaciers", Philos. Trans. R. Soc. Lond. 147 (1857): 327–46] before the end because of headache.

Thanks THH for his response on glacial movement. Hopes Tyndall will experiment on broken ice and explain how two pieces of ice can freeze together.

Sorry to hear of THH’s row with Richard Owen.

Asks THH’s opinion on embryological views of G. A. Brullé [Ann. & Mag. Nat. Hist. 13 (1844): 484–6] and F. M. Barnéoud [Ann. des Sci. Nat. ser. 3, Bot. 6 (1846): 268–96] and on Milne-Edwards’ classification.

Has been reading John Goodsir ["On the morphological constitution of the skeleton of the vertebrate head", Edinburgh New Philos. J. 2d ser. 5 (1857): 123–78].

Has embryology of bats ever been worked out?

Thanks THH for his cautionary response on Brullé, but departs from THH in thinking that Barnéoud, if true, would shed light on Milne-Edwards’ proposition that the wider apart classes of animals are the earlier they depart from common embryonic plan.

Thanks for three last lectures and the account of cirripedes.

Difficulty of classifying the higher groups.

Agassiz’s superficiality and wretched reasoning powers. But he stirred up Europe on glaciers. Lyell has been working on their effects – testing work of others.

CD believes "Natural Systems" ought to be simply genealogical. "Time will come when we shall have true genealogical trees of each great kingdom of nature."

Thinks naturalists look for something further than Cuvier’s view of classification. Poses a theoretical problem on the classification of the races of man to prove that a genealogical system is best.

Glad THH has taken up aphid question versus Owen ["On the agamic reproduction and morphology of Aphis", Trans. Linn. Soc. Lond. 22 (1858): 193–236].

Fertilisation and inheritance discussed. Speculates that fertilisation may be a mixture rather than a fusion. Can understand in no other way why crossed forms tend to go back to ancestral forms.

THH’s catalogue [THH and R. Etheridge, A catalogue of the collection of fossils in the Museum of Practical Geology (1865), part published in 1857] best résumé he has seen of science of natural history. On classification he is not quite sure that he wholly goes along with THH. Encloses a few criticisms of THH’s preface.[enclosure survives as copy only].