724 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Conditions of Development in Paragonimus.* — P. E. Garrison 

 and R. Leynes have experimented with the miracidium of the lung-fluke. 

 Temperatures above 15° C. are required for the development of the ova. 

 but temperatures as low as 10° do not impair their vitality. Direct sun- 

 light is fatal, and light is not necessary to the development of the egg to 

 the miracidial stage. Salt solutions are unfavourable, and above 1 ■ 5 p.c. 

 fatal to the development. Desiccation even for a few moments is fatal, 

 and the ova cannot be disseminated except in water. 



Nitzschia.|— F. S. Monticelli discusses the tristomid Trematode 

 Nitzschia elegans Nitzsch, which occurs in the branchial cavity of the 

 sturgeon. 



Hermaphroditism in a Nemertean.}— M. Oxner describes the re- 

 production in (Erstedia rustica. He does not agree with Joubin, who 

 discovered and described it, in regarding this form as having the sexes 

 separate. His investigation of 750 specimens in different months showed 

 that the form produces throughout the whole year eggs and sperms at the 

 same time. It has a very complicated perennial cycle of periodic repro- 

 duction. The author attributes the occurrence of hermaphroditism — 

 rare among Nemerteans — in (Erstedia rustica to the special and very 

 abundant nourishment afforded by the debris of the Ascidian Cynthia 

 rustica, on which it feeds. It is to this diet that the bright red colouring 

 of the species is due. 



Incertse Sedis. 



Attachment of Brachiopods.§— N. Yakowlew discusses the different 

 modes of attachment in Brachiopods — especially Spiriferacea and Tere- 

 bratulacea — in relation to classification. Individuals differ in attach- 

 ment, and distinctions of shell-shape result, which cannot be regarded as 

 of specific value. The type of the genus Gyrtis (G. exporrecta Dalm.) is 

 synonymous with Spirifer plicatellus, the presence in Gyrtis of a pedicle 

 opening in the pseudodeltidium being inconstant. In fact, G. exporrecta 

 represents the individuals of Spirifer plicatellus, differing primarily in the 

 growth of an elevated area, and the correlative appearance of a circular 

 opening in the pseudodeltidium. 



Metamorphosis of Alcyonidium mytili.||— A. Zschiesche finds that 

 sexually mature zocecia occur at almost every time of year. The time 

 for free larvae varies a good deal. Smooth surfaces are preferred for 

 attachment. The " pyriform organ " is used for orientation on the sub- 

 stratum. 



The fixation and the subsequent metamorphosis is described in 

 detail, the following points receiving special attention : the evagination 

 of the vestiliuluin ; the extension of tire dorsal larval region, and the 

 deformation of the ciliated wreath ; the coalescence of the margin with 

 the plate of attachment ; the invagination of the dorsal disc, and the 



* Philippine Journ. Sci., iv. (1909) pp. 177-83. 



t Atti R. 1st. d'Incorag. Napoli, vi. (1909) pp. 141-G2 (1 pi.). 



X Coinptes Rendus, cxlviii. (1909) pp. 1633-5. 



§ Mem. Com. Geol. St. Petersbourg, xlviii. (1908 ) pp. 1-32 (2 pis.). 



|| Zool. Jabrb., xxviii. (1909) pp. 1-72 (5 pis. and 3 figs.). 



