

-v. /. HcA^----^ 



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A MONOGRAPH OF THE PHYLLOPOD CRUSTACEA OF NORTH 

 AMERICA, WITH REMARKS ON THE OKDER PHYLLOCARIDA. 



By a. S. Packard, Jr. 

 Plates I— XXXVIII. 



CONTENTS. 



I. — Classificatiou of liviug species. 



II. — Geological succession. 

 III. — Geographical distribution. 

 IV. — External and iuternal anatomy. 



V. — Development and metamorphoses. 



VI. — Relation to their environment; 

 habits. 

 VII. — Relations of the Phyllocarida (Ne- 

 balia) to the Phylloiioda. 

 VIII. — Bibliography. 



The Phyllojiods constitute a division or suborder of the BrancMopoda, 

 an order of Neocaridous Crustacea, intermediate between the Unto- 

 mostraca (represented by the Copepoda and parasitic forms or fish-lice) 

 and the Malacostracous Crustacea (Tetradecapoda and Decajjoda). 

 They inhabit fresh water alone, in a few cases brackish water or strong 

 brine, but none dwell in the sea. 



The Phyllopod Crustacea are especially characteristic of the western 

 plains of our Territories, where the most striking and typical forms 

 abound, one entire family [Apodidce) not occurring east of the western 

 edge of the Mississippi Valley, while the most bizarre member of the 

 entire group, the Thamnocephalus, lives in pools on the plains of Kansas. 



These Crustacea are of singular beauty and interest in themselves. 

 The outlines of the BrancMpodidce are interesting, and their movements 

 while swimming on their backs are singularly graceful. Moreover, 

 when we consider the habits of all the Phyllopods; their singular means 

 of adaptation to great changes in their environment; the great vitality 

 of the species ; when we take into account their weak and delicate indi- 

 vidual organization, and when we note their interesting metamorphoses 

 and many points in their structure, we are forced to conclude that the 

 Phyllopods are the most interesting of all the Crustacea. 



The materials for this monographic account of a most interesting group 

 of Crustacea have been accumulating for over ten years. 



My collection has consisted of specimens obtained by the various gov- 

 ernment surveys and sent to the Smithsonian Institution, and received 

 from the late Dr. Stimpson, secretary of the Chicago Academy of Sci- 

 ence, shortly before the Are which destroyed the museum of the acad- 

 emy. A large and very valuable collection was made for me by Dr. L. 

 Watson, of Ellis, Kans., while a very valuable collection from Fort 

 Wallace, Kansas, has been kindly loaned me by Prof. Joshua Lindahl, 

 of Augustana College, Rock Island, 111. I am also indebted to the Pea- 

 body Academy of Science, Salem ; the Museum of Comparative Zoology 

 at Cambridge, for the loan of specimens, as well as to the Museum of 

 Yale College ; and to Dr. C. F. Gissler, Mr. W. P. Seal, Mr. S. A. Forbes, 



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