[ 



77 



and Mr. Ohiirles French, Melbourne, Australia, 

 Calcutta, British India, and Mr. W. M. Schoyen 

 were proposed for forei^m membership. 

 The following paper was then presented: 



Mr. E. C. Cotes, 

 Christiania, Norway. 



HYPODERAS COLUMBiE— A NOTE. 



By D. kS. Kkllicott, Columbus, Ohio. 



In April last a student in the laboratory of the Ohio State CTniversity 

 called my attention to the peculiar appearance of the thymus of a do- 

 mestic pigeon which he was dissecting. Examina- 

 tion soon showed that numerous individuals of a 

 mite were the cause of the mottled and granular 

 appearance which attracted attention. 



The species seems to be Rypoderas colitmbce, al- 

 though the archaic figure published by the de- 

 scriber and copied by Murray must leave some 

 doubt. 



The facts of its occurrence are as follows : About 

 a dozen pigeons were examined for the parasite, 

 and all the older ones, about half the number, har- 

 bored some examples. Two were found containing 

 multitudes 5 they were lodged in the substance of 

 the thymus and in such numbers, in the two, as to 

 strikingly change its appearance, as noted above. 

 They were also in great numbers about the pre- 

 cava and its branches. A few were seen in the 

 loose tissue about other vessels of tlie thorax and 

 in the subcutaneous. 



In the thymus the mites were found somewhat 

 parallel in groups of half a dozen or more; the in- 

 dividuals of the groups were held together by a de- 

 bris consisting mainly of granules and numerous 

 blood corpuscles. From material preserved some time in alcohol the 

 mites could be dissected out as from a cyst. 



The relatively long, slightly depressed animals, by measurement of 

 a large number, gave dimensions as follows: length, 1.5™"^- width 

 ,45""'" ® " ? ? 



The sketch will show in detail the form of body, position, and structure 

 ot the appendages. Figure 7 represents the average example seen from 

 below, magnified 56 + times. A, the chitinous framework about the 

 anterior pairs of legs; this extends upwards and anteriorly upon the 

 dorsal aspect; B, the chitinous framework about the posterior pairs of 

 legs; 0, three chitinous buttons. 



\ 



/ 



Fig. l.—Hypoderas colum- 

 Ice: highly magnified; 

 A, chitinous framework 

 about anterior legs ; B, 

 chitinous framework 

 about posterior legs : C, 

 chitinous buttons (Kel- 

 licott del.). 



