October 18, 1912] 



SCIENCE 



531 



18-31, and Naidium by O. Schmidt in 1847. 

 In 1875, Beddard combined them under the 

 prior name. In 1900, Michselsen restored them 

 as separate genera, and again combined them 

 in 1909. These two genera are more alike 

 than any other two genera in the family 

 Naididffi, and than many species in some of 

 the genera. They differ only in the develop- 

 ment of the prostomium, which varies widely 

 within the same species, and in the presence 

 of bifid setsB in the dorsal bundles of Naidium. 

 This is no more reason for keeping them 

 apart than it would be to make Nais tortuosa 

 and N, parviseia separate genera, because the 

 latter has bifid setag in the dorsal bundles. 

 Michselsen, in recombining the two species, 

 gives no reason for so doing; but Walton 

 (American Naturalist, Vol. XL., 1906, p. 705) 

 eays: 



The absence of any tentacular process in 

 Naidvum osborni suggests that until a species is 

 found in which the process is well developed and in 

 which the dorsal bundles contain biuncinate setae, 

 the genera may be considered distinct. 



Walton prophesies the finding of such a 

 species, and apparently suggests the inference 

 that when such a species is found the genera 

 need no longer be considered distinct. This 

 species has been found and wiU be more fully 

 described in a later paper on the Naididse. 

 It was found at the University of Virginia 

 in the spring of 1909, in an aquarium stocked 

 from a small pond in the neighborhood. It 

 differs from Pristina hreviseta of India only 

 in length, being considerably shorter, not ex- 

 ceeding 8 microns in length, but is otherwise 

 identical and it seems best not to establish a 

 separate species to receive it. In the Amer- 

 ican forms of this species the tentacular proc- 

 ess varies greatly in length. In one individ- 

 ual it was not developed at all, in others it 

 was developed to a length of several microns, 

 and intermediate lengths are numerous. There 

 are always, however, the bifid needle-like 

 setae in the dorsal bundles. But if we are to 

 make this a generic character, why not make 

 the presence of serrations on the capilliform 

 setae a generic character? And while we set 

 off those forms with the bifid setse in the 



dorsal bundles and no well-developed tentac- 

 ular process, what shall we do with Pristina 

 dadeyi, which has neither tentacular process 

 nor bifid dorsal setse? Michaelsen's recombi- 

 nation of the two genera, therefore, is con- 

 firmed by the finding of this form, and it is 

 correct to include under the head of Pristina 

 all the species hitherto described under the 

 heads of Pristina and Naidium, whether the 

 prostomium be tentacular or not, whether the 

 capilliform dorsal setae be serrated or not, and 

 whether the dorsal bundle contain a bifid 

 needle-like seta or not. These characters are 

 found in parts which vary greatly and the 

 great resemblances among the various species 

 in the position of the setae and of the internal 

 organs are more important. 



HoBACK Edwin Hayden, Jr. 

 College Station, Texas 



concurrent infection by five species op 

 intestinal worms, including schisto- 

 soma mansoni 



Instances of the presence of two or more 

 species of parasitic worms in one person are 

 common and many such are on record. To 

 cite some of the more recent literature. Garri- 

 son and Stiles, '06, in an examination of 

 3,457 persons, found that thirty-five harbored 

 twp species of intestinal parasites and that 

 one was infected with three species. The 

 Porto Eieo Anemia Commission, in the 

 course of its very extended studies, found fre- 

 quent instances of double infection, not rarely 

 triple infection, and, in two cases, determined 

 the presence of four distinct species. Piraja 

 de Silva, '09, working in Bahia, Brazil, re- 

 ports several similar cases of quadruple in- 

 fection. A case which has recently come to 

 my attention is of interest not only as an ex- 

 treme case of concurrent infection but as one 

 of the few known instances of the occurrence 

 of the blood-fluke. Schistosoma mansoni, in 

 the United States. 



On May 3, a local physician sent to me, 

 with the request that I make a blood exami- 

 nation, a Porto Eican who exhibited obscure 

 symptoms suggestive of filarial infection. 



