308 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 112 



same individual host. Specimens of the males of both genera are 

 extremely rare. There are in my collection only 7 species of Tro- 

 chiloecetes represented by males, and only 1 species of the Ricinus-like 

 form, it being represented by two males (from Selasphorus flammula) . 



Generally speaking, Trochiloecetes and Ricinus are not strikingly 

 different in appearance, except in the shape of the head and pro- 

 thorax, and in the male genitalia. In overall appearance the species 

 of Ricinus which parasitize the hummingbirds resemble closely a 

 few species of the genus found on other families of hosts. The 

 mouth parts, however, are entirely different and resemble those of 

 Trochiloecetes. 



The first species of Trochiloecetes to be described was prominens, 

 under the old generic term of Physostomum, from Calypte costae. In 

 1903 doratophorus was described by the present author from Selaspho- 

 rus flammula. In 1913 Paine and Mann described a third species, 

 emiliae, and placed it in the new genus Trochiloecetes. They desig- 

 nated Physostomum prominens Kellogg and Chapman the type of this 

 new genus. A fourth species, ochoterenai, was described by Zavaleta 

 in 1943, from Selasphorus rufus of Mexico, but the status of this 

 species is in doubt, as will be explained below. 



Meanwhile, none of the various authors who had worked with 

 the genus seem to have noted that the mouth parts were entirely 

 different from those of all other Mallophaga. In 1949 Clay published 

 a short article which briefly described the differences and showed 

 that the mandibles are not of the ordinary chewing type, but of a 

 piercing character. 1 This condition would seem to be ample proof 

 that this insect feeds on blood instead of feathers and scales of skin; 

 however, the theory was further substantiated by the presence of a 

 long, slender tube lying between the mandibles, the tube apparently 

 used for sucking blood from the punctures or scarifications made by 

 the pointed mandibles (see fig. la). Clay has elaborated somewhat 

 on the details of these structures and has advanced theories as to their 

 origin. 



As stated above, the species of Ricinus (auct.) found on the Tro- 

 chilidae possess mouth parts similar to those of Trochiloecetes (see 

 fig. 1/), but quite different from those of the species of Ricinus 

 (auct.) found on other families of birds. These mouth parts are of 

 a somewhat different type than those of other genera of Amblycera, 

 the differences being in the tj^pe of articulation and in the absence 

 of "teeth" on the inner side of the mandibles in Ricinus. 



Some forms of Ricinus (auct.) have mandibles that are exceedingly 

 minute (Dysthamnus mentalis, fig. 16), but not more so than in some 

 other genera of Amblycera, and others (Phlerjopsis n. nigromaculatus, 



1 Nature, vol. 164, p. 617, Oct. 8, 1949. 



