ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 549 



dealing with the Molluscs. We record it particularly Lecause of the 

 notes on the occurrence, mode of life, and breeding season of the forms 

 catalogued. 



y. Gasteropoda. 



Classification of Neomenians.*— G. Pruvot divides the Neomenians 

 into four families, of which he gives diagnoses: — (1) Lepidomenidaa, 

 the most primitive family, represented by the genera Lepidomenia, 

 Ismenia, Stylomenia, Dondersia,Nematomenia, Myzomenia; (2) Neomenidae, 

 represented by the single genus Neomenia ; (3) Proneomenidaa, repre- 

 sented by Proneomenia, Amphimenia, Eehinomenia (3), Notomenia, Stropho- 

 menia, Rhopalomenia, and Pruvotia ; (4) Paramenidae, represented by 

 Marcellomenia, Paramenia, and Pararhopalia, three genera which re- 

 spectively connect this family with the three cither families in the order 

 given above. 



The (Ji aetoderrnidae are regarded as derived from a Neomenian stock 

 which Proneomenia and Notomenia most nearly represent. Perhaps the 

 Neomenians and the Annelids both diverged from a Turbellarian stock. 

 The Neomeniaus and the Solenogastres, as a whole,, convey the impres- 

 sion of being a debilitated race, perhaps handicapped by the close and 

 inhibiting structural relations between the heart and the genital 

 apparatus. The Placophora, freed from this imperfection — " une tare 

 originelle " — have progressed, but the Solenogastres represent a cul-de- 

 sac in evolution. 



Development of Paludina vivipara.f — Isabella M. Drummond has 

 studied this subject with special reference to the urinogenital organs, 

 and to the theories of Gasteropod torsion. 



'1 he functional kidney of the adult belongs morphologically to the 

 definitive left side of the body, as von Erlanger has pointed out ; but 

 the definitive right kidney is not lost, as that authority described ; it 

 persists as the genital duct. 



An indication of the original coelomic connection between gonad and 

 kidney is found in the course of development as a thickened ridge of 

 pericardial epithelium, which finally becomes indistinguishable from the 

 f.'onad, and, after it has acquired a lumen, communicates with the de- 

 finitive left kidney close to the reno-pericardial aperture. The gonad 

 arises as a solid proliferation of the morphologically dorsal wall of the 

 pericardium. It arises from the original left side only, and shows no 

 sign of a paired origin. 



Theories of Gusteroi od torsion may be divided into two classes : — 

 (a) Those which view the present position of the pallial complex as due 

 to a forward movement along the right side of the body, which resulted 

 from greater growth of the left side of the body than of the right ; and 

 {{/) Those which view the present position of the pallial complex as due 

 to a ventral flexion followed by a vertical rotation of the whole visceral 

 hump upon tho head. 



The evidence for the second of these views seems greater than that 

 for the first, in that — 



(1) A vertical displacement through 180° of all the organs con- 

 tained in the visceral hump takes place in the course of ontogeny ; 



* Arch. Zool. Expe'r., x. (1902) Notes et Revue, pp. xvii.-xxvii. 

 t Quart. Journ. Micr. Sci., xlvi. (,1902) pp. 97-143 (3 pis.). 



