26 SUMMARY OF CURRENT RESEARCHES RELATING TO 



the same. But in Pulmonates (Stylommatophora) there is a clear 

 difference between the primary pulmonary cavity and the secondary 

 mantle cavity. The lung of Stylommatophora is a special organ ; it is 

 not a part of the general mantle cavity, but simply opens into it like the 

 ureter or genital duct. The branchial cavity of Prosobranchs is repre- 

 sented in Ario ii by the deeply insunk right portion of the mantle 

 groove, which for a time receives the opening of the pulmonary cavity. 

 Lung and mantle-cavity are quite different, but branchial cavity and 

 mantle-cavity are the same. 



Polar Bodies in Arion empiricorum.* — Honore Lams describes 

 the large ovum of this slug, the expulsion of the two polar bodies, the 

 division of the first, and the reduction of the chromatin. He records 

 a number of curious anomalies, such as gigantic polar bodies. 



Topographical Memory in Limpet and in Calyptraea.t — H. Pieron 

 hns made numerous observations and experiments showing the " homing " 

 habit in both of these Gastropods. He confirms previous work on the 

 limpet, and maintains that this animal has a knowledge not only of its 

 particular spot, but of its surroundings. By a method of exclusion he 

 shows that we must at present believe that the limpet has a topographical 

 memory. In Galyptraea there is also evidence of "homing," but it 

 seems to be less precise. 



New Family of ^lolididae.J — A. Vayssiere establishes a new genus 

 Eliotia, nearly related to Madrella. The two are referred to a new 

 family (Madrellidae) within the iEolididae. In the new family the 

 dorsal tentacles, or cylindro-conical rhinophores, show round their upper 

 half numerous tubular, simple, contractile digitations. There are mas- 

 sive, very thick, horny, but somewhat soft jaws, not lamellar as in 

 iEolids in general. The new family should be ranked near the Cory- 

 phellidae. Yayssiere found the type of his new genus, Eliotia souleyeti, 

 among the debris of Polyzoa in the Gulf of Marseilles. 



Adductor Muscles.§ — F. Marceau has made a detailed study of the 

 structure and functioning of the adductor muscles in a representative 

 series of bivalves. He discusses the nacreous and vitreous portions, the 

 contractility, the force exerted, the relation between the structure of the 

 fibres and the rapidity of their contraction, and many other points. We 

 may refer to the interesting discussion of fibres with smooth helicoidal 

 fibrils, which, though quite different from cross-striped muscle, are able 

 to contract with equal rapidity. 



S Lamellibranchiata. 



Malacology of Equatorial Africa. || — L. Germain gives an account of 

 the fresh-water bivalve Chelidonopsis, a highly evolved genus of Mutelidse. 

 He discusses the differences between Mutelidae and Unionidse, and the 

 various genera of Mutelidse. He considers the molluscan fauna of Equa- 

 torial Africa in general, and seeks to map out the migratory paths of 



* Arch. Zool. Exper., ser. 5, i. (1909) Notes et Revue, No. 1, pp. i -ix. (1 fig.). 

 t Tom. cit., pp. xviii.-xxix. J Comptes liendus, cxlix. (1909) pp. 636-7. 

 § Arch. Zool. Exper., ii. (1909) pp. 295-469 (4 pis. and 91 figs.). 

 || Op. cit., i. ser, 5 (1909) pp. 1-195 (2 pis.). 



