32 Trans. Acad. Sci. of St. Louis. 



uses which have been developed consist, of either a high 

 specialization of the front pairs of legs into chitinous 

 claspers shown on PI. V, Fig. 19, in the development of 

 the maxillary lip so as to form two curved, shovellike 

 claspers, or in the special modification of the hind group 

 of legs into clasping structures. A careful examination 

 of these clasping organs shows that they can only be used 

 upon a hair of almost a definite diameter and even of a 

 definite shape. A hair much larger than those of the 

 accustomed host would frequently be too large even to 

 permit the presentation of the claspers, while a hair 

 much smaller could not be held tightly at all. 



A List of the Analgesidae Found upon Moke than One 

 Host Species, Together with the Names of Their 



H0STS.^° 



Pterolicheae. 



freyana Haller. 

 F. gracilipes Trt. & M6gn. — Grus antigone (L.), Ephippiorhynchus sene- 



galensis (G. Shaw), 

 F. pelargica Trt. & M6gn. — Ciconla clconla (L.), C. nigra (L.), Euxe- 



nura maguarl (Gm.). 

 F. anserina Trt. & M6gn. — Anser anser (L.), Cygnus olor (Gm.), Chen 



hyperboreus (Pall.). 

 F. anatina (C. L. Koch) — Anas acuta L., A. crecca L., A. querquedula 



L., Mergus serrator L., Fuligula fuligula 

 (L.), Nettapus auritus (Bodd.). Other 

 water birds. 

 F. leclerci Trt. — Lobivanellus senegalus (L.), L. Indlcus (Bodd.). 

 F. caput-medusae Trt. — Sula bassana (L.), and other species of the 



genus. 

 F. gigas Trt. — DIomedea nigripes Audub., and on related species. 



pterolichus Eobin. 



p. lunulatus (Haller) — On species of Strlgidae. 



P. denticulatiis M^gn. & Trt. — Pyrrhula cruentata (Wied), and Amer- 

 ican parrots. 

 P. canestrinii Trt. — Ara macao (L.), A. canga, A. severa (L.). 



^" The following list has been compiled chiefly from Canestrini's mono- 

 graph of the family published in 1899. Des Tierreich, Lieferung 7. 



