36 PROCEEDINGS OF THE ACADEMY OF [1890. 



February 4. 

 Mr. William W. Jefferis in the chair. 



Twenty persons present. 



A paper entitled " The Genesis and Horizons of the Serpentines 

 of South Eastern Pennsylvania," by Theodore D. Rand, was pre- 

 sented for publication.. 



February 11. 

 Dr. Charles Schaeffer in the chair. 



Seventeen persons present. 



Papers under the following titles were presented for publication : — 

 " Note on a Southern Pupa." By H. A. Pilsbry. 

 " A Review of the Cernaycian Mammalia." By Henry Fairchild 

 Osborn. 



" On Arenicola cristata and its Allies." By J. E. Ives. 



February 18. 

 Mr. Harold Wingate in the chair. 

 Nineteen persons present. 



A Remarkable Variation of Sternonitis Bauerlinii, Mass. — Dr. 

 George A. Rex presented a series of specimens illustrating a strong- 

 ly marked variation of Sternonitis Bauerlinii Mass., and the succes- 

 sive phases of its reversion to the typical form. 



Four years previously, he had found on the surface of a decaying 

 log in Fairmount Park, Phila., a patch of sporangia of a Sternonitis 

 which, by a superficial inspection appeared to be Sternonitis Mor- 

 gani Pk. Subsequent examination with the microscope, however, 

 showed certain peculiarities of structure, not found in any known 

 species of Sternonitis. These variant characters were so marked that 

 they would have justified, had they proved constant, the creation 

 of a new species and also, perhaps, a new generic type. 



All of the sporangia of the entire growth which covered a super- 

 ficial area of five or six square inches, were alike in structure and 

 perfectly mature, so that their unusual form was not due to irregu- 

 lar individual development or immaturity. The sporangia differed 

 in form from typical Sternonitis, in being irregularly three-sided, or 



