/ WILLIAM H. DALL 

 'SECTIONAL LIBRARY 

 DIVISION OF. MOLLUSKS 



^. 



YIII. PlIYLOGENY OF THE PeLKCYPODA. 



The AvicuLiDiE and their allies. 



By Robert Tracy Jackson, S.D. 



mvUbD of Mollusks 



Sectional library 



I. Introduction .... p. 

 II. Sources of material and nietiiods of 

 work ..... i> 



III. Classification of stages of growth and 



decline ..... p 



IV. Ostrea : development of the soft parts ; 



embryology . . . . p 



V. Ostrea : development of the soft parts ; 

 the spat ..... p 

 VI. Ostrea : development of tiie shell p 



VII. Gryphrea, Exogyra and adult Ostrea, 

 with a consideration of the mechani- 

 cal origin of the ostrean form of shell p. 317 

 VIII. Perna, Avicula and near allies . p. 327 



XVII. 



XVIII. 



Pecten : anatomy and iiabits . p. 333 



Pecten : the shell ... p. 342 



Genera allied to Pecten . . p. 350 



Anoraia : anatomy .and habits . p. 354 



Anomia : the shell ... p. 359 



Studies of a few other genera . p. 362 

 On the genetic relations of the Pro- 



dissoconch .... p. 375 

 Genealogical connection of the 



Aviculidiie and their allies . p. 379 

 List of papers quoted or referred 



to in the text ... p. 394 



Description of plates. . . p. 395 



I. Introduction. 



i\X Y palfEontological studies have been carried on at the Museum of Comparative Zo- 

 ology as a pupil and assistant, first of Professor I^athaniel S. Shaler and later of Pro- 

 fessor Alpheus Hyatt. To these gentlemen first are due my acknowledgments in this 

 papei', which was offered as a thesis for the degree of Doctor of Science at Harvard Uni- 

 versity May 1, 1889.1 Acknowledgments are next due to Mr. Alexander Agassiz for 

 the opportunity to study the collections in the Museum. 



The investigations on which this paper is based were made while associated with Pro- 

 fessor Hyatt in the Palfeontological Department of the Museum.^ I have applied some 

 of the jM-inciples which he has deduced as a result of his scientific work, but I wish to 

 state that he has never urged his views ui)on me, or pointed out their application in the 

 Pelecypods. At Professor Hyatt's special request, I have used entire freedom in reject- 

 ing or criticising his views whenever they seemed not in accordance with the facts pre- 

 sented. 



' On account of new m.iterial obtained, some addi- 

 tions have been made to tliis paper since it was read be- 

 fore tlie Society on April 3, and since it was offered as 

 a tliesis on May 1, 188'J. The additions (or tlie most part 



MEMOIKS BOSTON SOC. NAP. HIST., VOL. IV. 



38 



liave been made to sections viii and xiv, and are indi- 

 cated Ijy the date of tlic collecting; of the material. 



'Three years have been spent in tliat department as- 

 sisting I'rofessor Hyatt arranjjiiig tlie great collections of 

 Fossil Invertebrates. 



(277) 



