Petrograd, [no publisher indicated], 1923. Large 8vo (25.1 x 16.6 cm). 361 pp., 138 text figures, two plates. Original printed wrappers.

Includes the sea urchins, with some new species. Perhaps all that has been published in this series, at least on sea urchins. Writtenn by the Russian zoologist (mainly ichthyologiust and echinodermatologist), and entomologist, Alexander Michailovitsch Diakonov, or Djakonov (1886–1956). Text uncut, partly unopened. Wrappers age-toned and a bit brittle at edges (the text pages, however, are on much better paper), vague stamp and cancellation stamp on front wrapper, otherwise clean. A very good copy. Rare.