14 



Avere possibly only geographical developments, but others repre- 

 sented distinct types not very nearly allied to any known species. 



Mr. F. E. Beddard, M.A., F.R.S., F.Z.S., Prosector to the 

 Society, read a paper dealing with certain points in the anatomy 

 of the Frog Megalophrys {Leptobrachiivni) fece, based on specimens 

 which had been exhibited in the Society's Gardens. 



Mr. Beddard also read a paper on the Spermatophores in 

 Earthworms of the genus Pheretima {^^Perichceta). These 

 structures had been found in two species, one of which would be 

 described as new, contained in a collection of teri^estrial Oligo- 

 chseta from the Philippine Islands, which had been submitted to 

 him for examination by the Director of the Scientific Bureau of 

 the Philippines. 



Mr. R. Lydekker communicated two short papers entitled 

 {a) "A Rare Beaked Whale," and (5) "Age Phases of the 

 Rorqual." 



Dr. P. Chalmers Mitchell, M.A., F.R.S., Secretary of the 

 Society, gave an account of his memoir entitled " On Longevity and 

 relative Viability in Mammals and Biixls ; with a Note on the 

 Theory of Longevity." The woi'k was based on a study of the 

 records of the duration of life in the Society's Gardens of over 

 20,000 individual Mammals and Birds. These were ari-anged 

 systematically so as to make possible a comparison of the average 

 duration with the maximum duration and what was known or could 

 be inferred as to the potential longevity. Such a method gave a 

 measure of the effect of the conditions of captivity on the duration 

 of life. The memoir discussed some of the results obtained by 

 such a comparison, j)articularly with regaixl to the provision of 

 artificial heat. In the note on the Theory of Longevity, the 

 author briefly reviewed the contributions of Ray Lankester, Weis- 

 mann, and Metchnikoff, and stated his conclusion that potential 

 longevity was due to constitutional causes, that the constitution 

 was adapted to the average specific longevity, and that the corre- 

 lation between longevity and reproduction was the reverse of 

 what had been suggested by Weismann. 



