April 30, 1920] 



SCIENCE 



441 



in the coldest part of the United States. In 

 summer, the lowest is in the lee of the Sierra 

 Nevadas. It is rather surprising to learn 

 that the July vapor pressures about Yuma- 

 ArLzona, in almost the hottest and driest part 

 of the Arizona desert are as high as those 

 about the cool Great Lakes. Nothing could 

 emphasize more strongly the fact that we feel 

 in terms of relative humidity rather than in 

 terms of absolute himiidity. 



In all the humidity tables and maps of Mr. 

 Day's contribution we see a complex weather 

 element which depends on the two variables, 

 temperature and moisture. Humidity maps 

 are in this respect on a par with snowfall 

 maps; but they are less complex than those 

 of evaporation, in which wind enters as an- 

 other factor. 



Charles F. Brooks 



SPECIAL ARTICLES 



LIMITS OF THE GENERA VANDELLIA AND 

 URINOPHILUS 



My monograph on the Pygidiidse was pub- 

 lished September, 1918. I was not able to 

 state the limits of the genus Vandellia nor to 

 indicate the type of the genus Urinophilus. 

 These minute fishes are found in the tropical 

 lowlands of South America. They attach 

 themselves to other animals and drink the 

 blood. Some of them are said to enter the 

 urethra of bathers, and being provided with 

 erectile, retrorse spines on the opercles can 

 not be withdrawn. If not excised they finally 

 enter the bladder and cause death. 



It was found during the preparation of the 

 monograph that some of the species contain 

 teeth on the mandibles, others not. It was 

 not known whether the type specimen of the 

 genus Vandellia contained mandibulary teeth 

 or not. The specimens are in the Jardin des 

 Plantes, Paris, and were not accessible during 

 the war. Dr. J. Pellegrin has recently ex- 

 amined these specimens and reports that the 

 types of Vandellia cirrhosa Cuv. & Val. and 

 of V. Wieneri do not have mandibulary teeth 

 and the name Vandellia may, therefore, be 

 restricted to those species without mandibulary 

 teeth, cirrhosa, plazai, wieneri and hasemani. 



The name Urinophilus becomes, thereby, re- 

 stricted to the only known species with teeth 

 on the tips of the mandibular rami, Urin- 

 ophilus sanguineus (E.). The species Urin- 

 ophilus sanguineus is known from one speci- 

 men, 62 mm. collected by Mr. Haseman at 

 San Antonio de Rio Madeiro, Brazil. Its 

 alimentary canal was gorged with blood. 



The genera Vandellia and Urinophilus are 

 members of the Pygidiidffi, a family of the 

 Nematognathi, the cat-fish-like fishes. In 

 most of these the maxillary is reduced to a 

 rudiment forming the base of the chief barbel 

 of the catfish. In Urinophilus and Vandellia 

 the maxillary bone carries peculiar claw-like 

 teeth. In the monograph mentioned above 

 the tooth-bearing maxillary was labelled " pre- 

 maxillary " in the explanation of Figs. 35 A 

 and B, and in Fig. 37. 



C. H. ElGENMANN 



THE AMERICAN ASSOCIATION FOR 

 THE ADVANCEMENT OF SCIENCE 



SECTION H— ANTHROPOLOGY AND PSY- 

 CHOLOGY. II 



Social differences in mental fatigue: T. E. 

 Garth. An experiment was given to school chil- 

 dren of three races— white, Indian and negro, in- 

 volving a simple task which all could perform. 

 The problem was to ascertain which race showed 

 least falling away in a task of continuous perform- 

 ance. The young group worked for twenty-eight 

 minutes and the older group for forty-two minutes. 

 The Indians, as a group, excel the whites in en- 

 durance but not in total performance. 



Supernormal memory: P. F. Swindle. Ordi- 

 narily, the term hysteria is a name applied to cer- 

 tain spectacular forms of behavior which arise 

 quite suddenly and which consist of strong and 

 very permanently associated responses. Such a 

 form of behavior may be called a somnambulism, a 

 fugue, a hysterical fit, or a special personality; 

 and it is manifested only by those persons in whom 

 associations are easily and at the same time quite 

 permanently formed. If, in this sense, a person 

 possesses an exceptionally good memory, a single 

 unusual occurrence will probably suffice to estab- 

 lish in him a series of strong responses which will 

 be manifested later as a somnambulism. It is 

 profitable to speak of "big" somnambulisms and 

 ' ' little ' ' somnambulisms, or spectacular somnam- 

 bulisms and ordinary somnambulisms. Hysteria is 



