IV CONTENTS OF VOLUME XX. 



No. 5. APRIL, 1911. 



HEGNER, ROBERT YV. Experiments with Chrysomelid Beetles. III. 



The Effects of Killing Parts of the Eggs of Leptinotarsa decem- 



lineata 237 * 



SCOTT, JOHN \V. Further Experiments on the Methods of Egg-laying 



in Amphitrite 252 



KEPNER, WILLIAM A. Nematocysts of Microstoma 266 



TANQUARY, MAURICE C. Experiments on the Adoption of Lasius, 



Formica and Polyergus Queens by Colonies of Alien Species. . . . 282- 



No. 6. MAY, 1911. 



CHILD, C. M. Experimental Control of Morphogenesis in the Regu- 

 lation of Planaria 309 



COCHRAN, M. ETHEL. The Biology of the Red-backed Salamander 



(Plethodon cinereus erythronotus Green) 332 



OSBORN, HENRY L. On the Distribution and Mode of Occurrence in 

 the United States and Canada of Clinostomitm marginatum, a 

 Trematode Parasite in Fish, Frogs and Birds 350 



COCKERELL, T. D. A. The Scales of Freshwater Fishes 367 



