No. 448.] NOTES AND LITERATURE. 



Mr. Brown's remark that the presence of the guanaco in Fuegia 

 while the deer, rhea and puma are absent from that island is 

 attributable to the agency of man rather than to the superior powers 

 of self-distribution possessed by the guanaco, may be correct, but the 

 latter hypothesis seems to me the more reasonable one. If the 

 presence of the guanaco in Fuegia is due to the agency of man, why 

 is the rhea absent from that island ? It is found quite as often in 

 captivity among the Indians, could have been just as readily trans- 

 ported and is more prolific than the guanaco. The readiness with 

 which the guanaco takes to water is well known in Patagonia as are 

 also its powers of swimming and to these characters is due I believe 

 its presence in Fuegia. The absence of the deer in Fuegia which, 

 as is well known, is also a ready swimmer is I think due to the fact 

 that it is a forest and mountain species and does not advance on the 

 plains as far as the "narrows" of the Magellan Straits. Farther 

 west the channels between Fuegia and the mainland are too wide to 

 be successfully crossed by either the deer or guanaco. 



The Rat-tailed Rotifers.^ — Jennings has published a most 

 interesting and valuable monograph of the Rattulid Rotifers, which 

 although a part of a series entitled " Rotatoria of the United States," 

 actually includes the species of the whole world. In fact, one new 

 species described {Diurella dixon-niittalli) has never yet been found 

 in America but only in England. The species are divided into 

 two genera ; Diurella in which the two caudal appendages or toes 

 are equal or the shorter is more than a third the length of the longer, 

 and Rattuliis, in which these organs are more unequal, one being 

 often quite rudimentary. The author states that these are not 

 natural genera, but are justified by considerations of convenience. 

 He remarks that the idea that all the species of a genus must be 

 more related to each other than to any outside species has been 

 largely given up in practice ; but this might be admitted and yet it 

 might remain true that the generic characters had not been acquired 

 independently. If the more primitive Diurella type has given rise 

 separately to two or more groups of species now included in Raitulits, 

 it will be necessary to either divide Rattulus into as many genera, or 

 unite Diurella and Rattulus under the latter (older) name. Of 



' Jennings, H. S. A Monograph of the Rattulid:e. Bulletin U. S. Fish Com- 

 mission for 1902 (1903). pp. 273-352- Pis. I-XV. 



