414 THE AMERICAN NATURALIST. [Vol. XXXVIII. 



five varieties, out of the total known number of one hundred 

 and thirty-eight species and nine varieties of Uving brachiopods. 

 This statement is taken from a hst kindly sent me by Miss 

 Lucy P. Bush, his assistant, who prepared it recently at Pro- 

 fessor Beecher's request. 



In corals he made important contributions by his beautiful 

 studies of the development of Pleurodictyum and also the struc- 

 ture and development of the zooids in the colonial form in 

 Michelinia, Favosites and recently in Romingeria. 



Thoroughly established in his adopted principles of research, in 

 1893 he began the publication of his brilliant papers on the struc- 

 ture, development and classification of the Trilobita. Favored 

 by the discovery by W. S. Valiant of Triarthrus in unusual con- 

 dition of preservation at Rome, New York, Beecher entered into 

 the work. The presence of antennae had been announced by 

 W. D. Matthew ; but Beecher with his marvelous mechanical 

 skill and untiring patience worked out the structure of antennae, 

 legs and other ventral appendages with a minuteness that had 

 previously been impossible on any known material. His studies 

 of this type made our knowledge of the Trilobita as a class a new 

 thing, putting them on a basis for proper comparative study with 

 other Crustacea. He also took up studies of the development 

 of Trilobita, describing the development in genera in which it 

 was previously unknown or partially known. In 1897 Beecher 

 presented a classification of Trilobita based on his critical studies 

 of young and adult structures together with a consideration of 

 the geological or time sequence, a natural basis for classification 

 as urged by Louis Agassiz and Alpheus Hyatt and nowhere 

 more beautifully carried out than in these trilobite studies. The 

 Trilobita were divided into three orders based principally on the 

 development of the free cheeks. At the time of his death he 

 was at work on an extensive monograph on the structure of 

 trilobites. 



In all of Beecher's later work a strong philosophical bent was 

 evinced. This was given full expression in his charming and 

 forceful papers on the origin and significance of spines. In 

 them he urged that spinosity is an expression of growth-force 

 and differential development. The spinose individual or group 



