September 24, 1920] 



SCIENCE 



291 



tively rough surface seems to act as a polished 

 mirror toward light striking it at a very small 

 angle of incidence. The mirage on the plains, 

 being a phenomenon of refraction, is of an 

 entirely different nature. 



H. H. Platt 



To THE Editor of Science : In his communi- 

 cation to the issue of August 27, Mr. F. W. 

 McITair touches upon a matter which seems to 

 me worthy of further consideration. 



In the course of numerous trips about the 

 country by automobile, I have had repeated oc- 

 casion to note the sort of mirage mentioned, 

 particularly on stretches of surfaced road. 

 The phenomenon commonly takes the form of 

 an apparent small pool of water, which appears 

 suddenly a little way ahead, and disappears 

 with equal suddenness. 



In most cases the reflecting air-surface would 

 appear to be only a few inches above the road: 

 the effect is that of a shallow pool, and one 

 involuntarily dodges the apparent depression. 

 On one or two occasions, however, I have noted 

 a reflecting surface high enough to cut off the 

 wheels of a vehicle driven through the lower 

 stratum of air. 



It occurs to me that the condition sug- 

 gested may serve in part to account for ideas 

 of temporary disappearance, or dematerializa- 

 tion, of solid objects, and for occasional ac- 

 counts of apparent hallucination. 



This matter would seem to be interesting and 

 important enough to warrant fuller discussion. 

 Freeman F. Burr 



Eattlesnake Island^ past which Perry 

 sailed his fleet to the battle of Lake Erie in 

 1813, lies two miles northwest of Put-in-Bay 

 and occupies about eighteen degrees of the 

 horizon. 



On Sunday, July 18, at about one o'clock, 

 while watching a thunderstorm approach over 

 Eattlesnake, a second island was seen, some- 

 what higher than the real one and shifted to 

 the westward approximately one third the ap- 

 parent length of the island. 



At first this was thought to be a mirage of 

 Middle Sister which lies some miles to the 



northwest. Two small islets, the Rattles, which 

 lie off shore from the western end of Eattle- 

 snake and which were projected to the left of 

 the phantom island, indicated, however, that we 

 were looking at an image of Eattlesnake. 



The apparition was seen from a cottage three 

 hundred yards to the southwest as well as 

 from the laboratory cottage. It persisted for 

 some time, possibly as long as fifteen minutes, 

 disappearing just before the sheets of rain 

 from the storm blotted out Eattlesnake en- 

 tirely. The outline of the real island was at 

 all times more distinct than that of the image, 

 which was — or seemed to be — slightly behind 

 it as well as above. 



Stephen E. Willums 



Lake Laboratory, 



Ohio State XJNryERSiTY, 

 Put-in-Bay, Ohio 



family and subfamily names in zoology 

 To THE Editor of Science: I have read 

 with much interest Oberholser's thirteen rules 

 for family and subfamily names appearing in 

 the issue of Science of August 13, 1920, which 

 he says have the approval, in part at least, of 

 thirteen named persons well known for their 

 work in systematic zoology. If Dr. Ober- 

 holser had stopped with number 12 his rules 

 would appear to be quite ideal. 



Why rule 13? Two family or subfamily 

 names having the same spelling are compara- 

 tively rare. They are for the most part going 

 to be used by persons who know what the 

 type genera are. It is quite inconceivable 

 that there would ever be any real confusion 

 because of identical spellings. If it is desir- 

 able to distinguish between two families or sub- 

 families that would be spelled alike by fol- 

 lowing rules 1 and 2, a prefixed Pro seems to 

 me to be the least desirable method. Any 

 one not familiar with the case would naturally 

 think the type genus of Propicidce to be either 

 Propicus or Propica. In Palmer's "Index 

 Generum Mammalium" there are over 100 

 generic or subgeneric names beginning with 

 the prefix Pro and at least half a dozen of 

 these names are used in forming family or 

 subfamily names. 



