178 SUMMARY OF CUKRENT RESEARCHES RELATING TO 



It was on Chromodoris reticulata that Crossland made his interesting 

 observations regarding the warning coloration of the genus. The 

 author notes : "My own experience does not entirely support his state- 

 ment that Chromodorids do not hide under stones but show themselves 

 in the open. I have often found them (as well as Trevelyana ci-ocea) 

 under stones on tropical beaches, where their vivid colours harmonize 

 wonderfully with the ascidians and sponges found in the same locality, 

 so that the nudibranch which when isolated is conspicuous, is almost in- 

 visible at home." But, as Crossland points out, many species are known 

 to arrive on the shore in considerable bands for the spawning season, and 

 perhaps all do so. At this critical period, at all events, warning colora- 

 tion must be useful to them. 



Structure of Pterotrachea mutica.* — A. Krasucki gives a detailed 

 and finely illustrated account of this Heteropod, dealing particularly with 

 the skin, the alimentary canal, the gills, the vascular system, the kidneys, 

 and the reproductive organs. 



Parasitic Gasteropods.f — Nils Eosen has made an important con- 

 tribution to our knowledge of parasitic Gasteropods. He takes a critical 

 survey of the forms hitherto known — the genera Stilifer Broderip (the 

 numerous alleged species of which are reduced to three), Mucronalia 

 A. Adams, StijUferina A. Adams, Stylina Fleming, EuJima Risso, Rohil- 

 lardia E. A. Smith, Pelse)ieeria Koehler and Vaney, an unnamed genus 

 described by Voeltzkow, Thyca Adams, Gasterosiphon Koehler and Vaney, 

 Entocolax Yoigt, Entoconcha Joh. Miiller, and Enteroxmos Bonnevie. 

 He establishes two new genera — Turtonia, with a single species T. 

 stylifera (Turton), extricated from the genus Stilifer, and Megadenus, 

 which comes nearest Stilifer and Mucronalia, and is represented by one 

 species, M. holothuricola. A detailed account is given of these two new 

 forms, and a comparative survey is taken. The relation of the parasites 

 to their Echinoderm hosts is then discussed, and the structural peculiarities 

 that may be associated with the parasitic life. The author discusses the 

 hasty derivation of the parasitic Gasteropodsfrom a EuUma-fitock ; he will 

 not commit himself to more than referring them to the Prosobranchs and 

 to the Monotocardia among these. The genus Thyca is to be referred to 

 the Capulidse. A new family, Turtoniids, is proposed for Turtonia and 

 Felseneeria. The Stiliferidre include Megadenus, Mucronalia, Stilifer, 

 Gasterosiphon. The Entoconchidas receive Entocolax, Entoconcha, 

 Enter oxenos. No other genera have been satisfactorily established. 



5. Lamellibranchiata. 



Development of Gills in Cyclas and other Fresh-water Bivalves. J 

 E. Wasserloos gives a detailed account of the development of the gills of 

 Cyclas cornea, and takes a comparative survey of what occurs in Galy- 

 culina, Pisidium, Unio, Anodonta, and Dreissensia. The internal gill may 

 be formed in two different ways. The fold-method, by the fenestration 

 of an originally continuous gill-fold, occurs in Cyclas, Galyculina, Pisidium, 



* Bull. Internat. Sci. Cracovie (1911) pp. 391-450 (4 pis.). 



t Lunds Univ. Arsskrift, vi. (1910) pp. 1-67 (4 pis. and 9 figs.). 



X Zool. Jahrb., xxxi. (1911) pp. 171-288 (4 pis. and 52 figs.). 



