70 THE NAUTILUS. 



scribed of the genera Pleurotoma (sensu latissirao), Cerithiella, 

 Amphirissoa (a new Rissoid genus with continuous, reflexed peri- 

 stome), Basilissopis (a new genus resembling Basilissa, but not 

 pearly, etc.), Enlima, Niso, Turbonilla, Turcicula, Cyclostrema, Coc- 

 ciilina, Puncturella, Acmcea, Aliceia (name preoccupied), Isomonia 

 (new group of Anomiidce), Chlamys, Amussium, Myrina,Arca, Leda, 

 Malletia, Cardium, Axinus, Diplodonta, Cusjndaria, Verticordia, 

 Thracia and Poromya. All the new forms are figured, but the pho- 

 totypes are not so clear in detail as we could desire, being decidedly 

 inferior to those illustrating " Les Mollusques Marins du Roussil- 

 lon," for example. Otherwise the work seems well done in every 

 respect. 



In treating the Scalidce and the genus Mathilda obtained by the 

 same expedition, 2 Mr. Dautzenberg has the able assistance of Mr. 

 E. de Boury, well known for his studies on Scalidce. Thirteen spe- 

 cies are recorded, of which seven are new. 



BREEDING SINISTRAL HELICES. Arnold Lang, in Vierteljahr- 

 schr. Naturf. Ges. Zurich, XLI, 1896, Jubelband, p. 448, gives the 

 results of two experiments to ascertain whether as a rule sinistral 

 individuals of normally dextral snails produced sinistral or dextral 

 young. The experiments were conducted two consecutive years, 

 once with seven, another time with nine individuals of Helix poma- 

 tia. They were completely isolated ; and the result was only dex- 

 tral young. No less than 241 young were obtained from the lot of 

 seven. 



Edwin Grant Conklin, Professor of Comparative Embryology in 

 the University of Pennsylvania, has published in the Journal of 

 Morphology for April, 1897, an elaborate work on the Embryology 

 of Crepidula, with especial reference to the " cleavage of the ovum, 

 the formation of the germinal layers and definitive organs, and the 

 axial relations of the ovum to the larval and adult axes." The 

 work is too extensive for abstract here, being, in fact, one of the 

 most thoroughly worked out studies in "cell lineage" yet produced 

 in America, and especially valuable for the attention given to the 

 later stages with the object of tracing the individual blastomeres of 

 the cleaving egg onward to the germ layers. The interesting obser- 

 vations upon the natural history of Crepidula forming part of the 

 prefatory portion of Prof. Couklin's memoir, we hope to reprint 

 later. 



2 Same volume. 



