Thanks JS for fossil cirripedes. Discusses the specimens. Sends thanks to J. G. Forchhammer for specimens.

Describes progress of research on fossil cirripedes. Comments on specimens sent by JS. Asks about age of several European formations, and for information about specimens.

Describes progress in illustration of fossil cirripede specimens. Thanks for answers to questions. Comments on hermaphroditism. Describes his discovery of parasitic male cirripedes.

Asks him to send additional cirripede specimens.

Fossil cirripede specimens have arrived.

Describes progress on his monograph [Fossil Cirripedia].

Would be grateful for the paper on Lithotrya. Asks for information.

Fossil cirripedes specimens being returned. Will send a copy of monograph [Fossil Cirripedia]. Discusses work on recent cirripedes.

Returns fossil cirripede specimens to JS and Forchhammer.

Sends copies [of Fossil Cirripedia] to them and to Sven Lovén.

Reading proofs [of Living Cirripedia].

Thanks him for specimens of Xenobalanus. Discusses systematic relations of the genus.

Comments on paper by J. T. Reinhardt ["Om slaegten Lithotryas", Vidensk. Medd. Naturhist. Foren. Kjobenhavn 2 (1850): 1–8].

Asks for reference to publication about Xenobalanus.

Asks JS to compare cirripede specimens with those of Lorenz Spengler to establish comparative nomenclature.

Requests reference to article describing Xenobalanus.

Offers to send collection of cirripedes to Copenhagen Museum in return for assistance in his research. Mentions publication of Living Cirripedia, vol. 2.