a 
Ve eee ee T n 
EE eae HN 
AMERICAN NATU RALISE 
Vac*XEeU o 0- November, 1803. | = 
ON THE GENERA OF THE DIPNOI DIPNEUMONES. 
By Howarp Ayers.’ 
The Dipnoi are a group of piscine vertebrates, unusually in- 
teresting, alike to the morphologist, the paleontologist and the 
physiologist. Hitherto these animals have proved, in many 
respects, unsatisfactory objects of study, since the existing 
forms have been accessible to but few workers, and then only 
as more or less poorly-preserved alcoholic specimens. Only 
within the last few years has this condition of things changed 
so that quite recently our knowledge of this group has been 
enriched by many interesting and important additions to the 
morphology, physiology and the general biology of two of the 
members of the group representing the two commonly accepted 
genera. 
The papers containing the results of the researches upon the 
living specimens of Lepidosiren annectens we owe to Professor J. 
Waldschmidt, who has worked out the Dipnoan brain from the 
comparative standpoint, and in histological detail, and to 
Professor W. N. Parker, who has studied in more or less detail 
almost all of the organs of the body except the skeletal and 
nervous systems. His study was directed to the solution of 
the numerous points left unsettled by previous workers who 
were less favored in the quality of their material, and not toa 
fundamental research into the nature and relationships of any 
1 Director of the Lake Laboratory, Milwaukee, Wis. 
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