2 Annals of the Carnegie Museum. 



The first Memoir to be included in Volume VIII of the Memoirs 

 of the Carnegie Museum was issued in December, 1919. It is the 

 final part of Dr. Arnold E. Ortmann's IVIonograph upon the Naiades 

 of Pennsylvania. 



The preparation of this work may be said to have been undertaken 

 at "the eleventh hour." The great river-system of the Ohio arising 

 in western Pennsylvania, western New York, and West Virginia, at 

 the time of the first occupation of the region by the whites was rich 

 in mollusca. In the process of time, with the great increase in popu- 

 lation, which has occurred, and the huge development of industrial 

 enterprises, which has taken place along the streams, these have become 

 more or less polluted. The flow into the rivers of water strongly 

 charged with sulphuric acid from the mines, the injection of waste 

 from various manufactories, the disposal of sewage by drainage it 

 into the streams, have gradually led to such contamination that the 

 fluvial fauna has become practically extinct over wide reaches of 

 the rivers, especially below the metropolitan area of Pittsburgh. 

 Where even only twenty years ago representatives of various spei;ies 

 of mussel-shells were still comparatively abundant they have now 

 ceased to exist. The shores of Neville Island below the city in the 

 last decade of the nineteenth century possessed a ver}' extensive 

 molluscan population, which is now dead and gone, as completely 

 extinct as the Indians, who once lived there, and derived part of their 

 sustenance from the beds of shell-fish, which were found along the 

 river. Fortunately the Carnegie Museum possesses several col- 

 lections made many years ago in the region, and the indefatigable 

 industry of Dr. Ortmann has supplemented these by great quantities 

 of specimens, which he has himself gathered, or secured through the 

 cooperation of others whom he has filled with his own enthusiasm. 

 He thus possessed as the basis of his labors material such as exists in 

 no other museum in the world, and his work will always remain a 

 monument not only to his learning but to his scientific energy. Alas! 

 it is in the main a record of that which is past. The rich fauna Avhich 

 once filled the streams is practically extinct, except as represented here 

 and there by remnants. The student of future years will find the 

 only memorial of this great assemblage of species in the cabinets of 

 the Carnegie Museum. 



From South America during the past ten months we have received 



