December 



1884. 



SCIENCE 



511 



and, if he would favor me with them, I should feel 

 much flattered, — firstly, his estimate, from the census 

 results, of the number of persons of the age of fifteen 

 and upwards, resident in the British Islands, whose 

 statements he would consider prima facie entitled 

 to full credence (to guide him I may remark that I 

 see no reason why the number should not be from 

 ten to twenty millions) ; secondly, his estimate of the 

 probability that one of these persons, taken at ran- 

 dom, would not be above amusing himself or herself 

 at the expense of a society so eminent as that of which 

 Mr. Gurney is the honorary and honored secretary. 

 These numbers will come into my discussion, and I 

 should much rather have them from an authority 

 conversant with the subject than attempt to guess at 

 them myself. 



Simon Newcomb. 



Change in the color of the eye. 



The experience of Mr. T. F. McCurdy (p. 452) is, 

 I imagine, a not uncommon one. It certainly finds 

 illustration in my own family and in myself; the iris, 

 which was quite black in childhood, having for many 

 years visibly lightened, until it is more correctly de- 

 scribed as gray, with shades of hazel. The fading-out 

 of black eyes with age is a matter of common obser- 

 vation ; and the change, judging from the facts within 

 ray own knowledge, is more apt to occur where the 

 individual takes after a grandparent who had the 

 dark eye, and where the immediate parents had blue 

 or gray. C. V. Riley. 



Washington, D.C. 



Specimens illustrating Lehmann's ' Origin of 

 the crystalline schists.' 



It may not be uninteresting to the geological read- 

 ers of Science to know that the writer has recently 

 received, through the kindness of Professor Johannes 

 Lehmann of the University of Breslau, a very valua- 

 ble suite of rock specimens illustrative of the latter's 

 new and important work on the origin of the crystal- 

 line schists, noticed in Science, No. 86, p. 327, and in 

 the American journal of science for November, 1884, 

 p. 392. These specimens are sixty-three in number, 

 and were collected, partly by Professor Lehmann him- 

 self, and partly under his immediate supervision, in 

 the granulite area of Saxony, and in those parts of 

 Bavaria which he has made the subject of his special 

 study. They exhibit in an excellent manner nearly 

 all those phenomena ascribed by the author of the 

 above memoir to metamorphism by pressure, espe- 

 cially, however, the changes which certain massive 

 pyroxene rocks of Saxony have undergone in becom- 

 ing hornblendic schists exactly analogous to similar 

 alterations traced by the present writer in the rocks 

 near Baltimore. 



To all students of metamorphism and of structural 

 geology in highly crystalline regions, this work must 

 be of absorbing interest as undoubtedly the most 

 advanced of its kind; and, in spite of its superb atlas 

 of most satisfactory photographic illustrations, its 

 readers may be glad to know that this suite of origi- 

 nal specimens is in the petrographical laboratory of 

 the Johns Hopkins university, where it will always 

 be accessible to such persons as may be interested in 

 examining it. Geo. H. Williams. 



Baltimore, ZSTov. 25. 



Bot-flies in a turtle. 



Some days ago Prof. T. Robinson of Howard uni- 

 versity called my attention to a box-turtle (Cistudo 



Carolina) which had in the muscles on either side of 

 the neck about thirteen large bot-fly larvae. The 

 turtle was alive, but evidently suffered inconvenience 

 from the intruders which had taken up their abode 

 at a point from which they could not be dislodged by 

 claw or beak. They were removed with forceps, and 

 sent to Mr. Howard of the agricultural bureau, who 

 informed me that they belonged to the family Oestri- 

 dae, and to a genus probably undescribed. He also 

 brought to my attention an exactly parallel case re- 

 ported in the American naturalist (xvi. 598) about 

 two years ago by Prof. A. S. Packard. 



Frederick W. True. 



U. 8. national museum, Washington, 

 Nov. 24. 



On the function of the serrated appendages 

 of the throat of Amia. 



Through the kindness of Prof. B. G. Wilder I have 

 at present two living specimens of Amia which I pro- 

 pose to employ shortly in a comparative study of the 

 brains of American ganoids. 



My attention was first attracted to the serrated 

 appendages of the throat by Professor Wilder's own 

 note upon the subject, published in the Proc. Amer. 

 assoc, 1876, and more recently by a reference to the 

 same structures in one of SagemehFs admirable con- 

 tributions to the anatomy of fishes (Morph. jahrb., 

 x. 63). Sagemehl concludes, from the examination of 

 alcoholic specimens, that these 'flagella' are, during 

 life, in constant motion, and thus help to renew the 

 water in the gill-cavity. Such is by no means the 

 case. The 'flagella' are attached by their bases to 

 the lateral aspects of the sterno-hyoid muscles (hyo- 

 pectorales of McMurrich), the chief function of 

 which is to enlarge the cavity of the mouth. When 

 these muscles are at rest, the flagella lie flat along 

 their surfaces: when they contract, the cavity of the 

 mouth is enlarged, the flagella erected, and the gill- 

 covers pushed outwards. At the suggestion of my 

 assistant, Mr. A. B. Macallum, we stimulated the prox- 

 imal part of the muscle with the result of a perfect 

 demonstration of the above facts. The flagella thus 

 help to replace functionally the absent dilatator mus- 

 cles of the gill-covers. A strip of condensed tissue 

 occupies a precisely similar position on the hyopec- 

 toral muscle of Amiurus, perhaps a rudiment of 

 similar organs possessed by the ancestors of the silu- 

 roids before the differentiation of the dilatator mus- 

 cles of the operculum. 



My specimens of Amia, after being in captivity for 

 some time, became very sluggish, and hardly any 

 movements of respiration could be detected. After 

 the fish had been removed for a little out of the 

 water, however, and then returned to it, the move- 

 ments were sufficiently active to disclose the follow- 

 ing facts: — 



During the enlargement and filling of the cavity of 

 the mouth, the posterior flexible (and muscular) bor- 

 der of the gill-cover is tightly applied to the soft 

 parts behind the gill-opening. When the mouth- 

 cavity is quite full, the mouth closes, the muscular 

 border of the gill-cover releases its sucker-like hold 

 of the soft parts, and the water is driven out by the 

 contraction of the walls of the mouth-cavity. 



Professor Wilder's account of the structure of the 

 serrated appendages is so complete as to render any 

 further reference to this subject unnecessary. 



R. Ramsay Wright. 



University college, Toronto, 

 Nov. 27. 



