242 TRANSACTIONS OF THE [JuNE 5 



May 29, 1892. 



Stated Meeting. 



Pkesidext Bolton in the chair, and fifteen persons pi'esent. 

 Dr. Marcus Benjamin read a paper entitled : " The Develop- 

 ment of Science in New York City." 



June 5, 1893. 



Regular Business Meeting. 



President Bolton in the chair, and five persons present. 

 The following papers were read by title : " The Chordeiimidse 

 of North America," by O. F. Cook and F. P. Collins. 



NOTE ON THE POSITION OF THE CLOACAE APER- 

 TURE IN CERTAIN BATRACHIAN TADPOLES. 



BY ARTHUR WILLEY. 



An interesting feature in connection with the study of Tera- 

 tology is concerned with disturbances in the tojjographical 

 relations of parts produced by mechanical means or, in other 

 words, by the differential growth of neighboring structures. 



One of the effects of such disturbances introduced secondarily 

 into the life-history of an organism, is to give rise to a condition 

 of asymmetry in the relations of this or that organ. At its first 

 appearance, in whatever form, an asymmetrical condition must be 

 regarded as anomalous, and we thus arrive at the paradoxical 

 conclusion that an anomaly may, on being fixed and rendered 

 constant by inheritance from generation to generation, become 

 the normal state of things. This is only another way of saying 

 that, "La teratogenic est capable de produire des especes 

 nouvelles." (See Paul Hallez, " Morphogenie generale et 

 affinites des Turbellaries." Lille 1892.) 



While examining recently a number of tadpoles, which were 

 identified with the assistance of Mary H. Hinckley's jmper 

 " On Some Differences in the Mouth Structure of Tadpoles of 

 the Anourous Batrachians found in Milton, Mass.," (Proc. Bost. 

 Soc. Nat. Hist. XXI., 1881, pp. 307-314, PL V.), as the probable 



