THE OPALINID CILIATE INFUSORIANS. 449 



rial of ProtoopaZina satuimalis is scant. Of a few other species there 

 are available less than 18 slides each. Most species, however, are 

 represented in the sets of slides distributed. 



Owing to an accidental contamination of the mounting medium, 

 not observed until nearly all the slides were made, the slides have 

 slowly faded, until now most are practically unstained. Fortunately 

 the fading was so slow that the author's cytological study of the 

 material was completed before much damage was done. The work 

 has involved making about 7,000 slides, and demounting and restain- 

 ing is too forbidding a task to be undertaken, especially as the un- 

 stained slides are of value for taxonomic study. 



The type series is in the United States National Museum, in Wash- 

 ington. The author retains a set of paratypes. In each of these 

 two series there are included specimens of each species, subspecies, 

 and forma of Opalinid from each host from which it is known and 

 from each major region of its habitat, so far as available material is 

 available. The other series are not quite so full. The author has 

 also a good many extra slides of most species and some unmounted 

 material of many species. So far as the stock left will allow, slides 

 or material of any species will be sent (of course, without cost), 

 upon request, to any student of this group who desires to make com- 

 parisons with his own material. Of course, extensive sets can hardly 

 be sent, because of the expenditure of time this would involve, but 

 requests for samples of a few species will gladly be met. Address 

 Maynard M. Metcalf , the Orchard Laboratory, Oberlin, Ohio, United 

 States of America, 



The institutions which have accepted sets of slides are : 



NORTH AMERICA. 



United States National Museum, Washington, District of Colum- 

 bia, United States of America. 



School of Hygiene and Public Health, Johns Hopkins University, 

 Baltimore, Maryland, United States of America. 



American Museum of Natural History, Seventy-seventh Street and 

 Central Park West, New York City, New York, United States of 

 America. 



Museum of Comparative Zoology, of Harvard College, Cambridge, 

 Massachusetts, United States of America. 



Department of Zoology, University of California, Berkeley, Cali- 

 fornia, United States of America. 



SOUTH AMBBICA. 



Oswaldo Cruz Institute, Eio de Janeiro (Manguinhos) , Brazil. 



