272 PROCEEDINGS OF THE ACADEMY OF [April, 



many species develop within the yet soft sporangium a stipe on which 

 they creep up, so that the matured sporangium is stipitate, and when 

 the stipe has a continuation within the sporangium, this is known as 

 a columella. 



The different species have more or less constant characters. Many 

 are never found stipitate. Among the stipitate forms it often happens 

 that a few of the sporangia of a gathering are sessile, especially spor- 

 angia maturing on the outside of the group. 



Two rather extraordinary gatherings were shown under microscopes. 

 The one was Physarum pulcherrimum, which is usually stipitate, 

 sessile sporangia being rarely seen; but in the specimens shown all 

 sporangia were sessile. The other exhibit was a specimen of Perichcena 

 chrysospora. Not a single species of this genera is known to be stipi- 

 tate, but in the gathering exhibited a number of the sporangia had a 

 well-developed stipe, while others were normal and therefore sessile. 



Mr. Silas Shumo. on the microscopic characters of the stems of 

 Equisetum. (No abstract.) 



Mr. Frank J. Keeley, on micrometry. (No abstract.) 



Mr T. Chalkley Palmer, on Navicula sociatis, a new diatom. 

 (See papers.) 



Mr. William B. Davis, on fresh-water polyzoa. (No abstract.) 



Mr. H. Van Sickel, on a new crystallization of platinum. (No 

 abstract.) 



The communications were illustrated by preparations under the 

 microscopes. 



Mr. John B. Henderson was elected a member. 



The following were ordered to be printed: 



