192 



SCIENCE 



[N. S. Vol. XXXVI. No. 919 



black and red. The unexpected appearance 

 of the dun and yellow birds is satisfactorily 

 accounted for on the assumption that she was 

 heterozygous, as follows : 



Parents: black ^ = fBI.fM 



red 2 =^fbI-Fbi 

 Gametes: (^, fBI, fBi, fbl and fbi 



2, fbl and Fbi 

 Combinations: fBI- fbl == black <? 



fBI. Fbi = h\a.Qk $ 



fBi -fbl = black <^ 



fBi -Fbi =:dun $ 



fbl. fbl =red d" 



fbl. Fbi =red $ 



fbi. fbl =red (? 



fbi. Fbi ^yellow J 



That is, 2 black males: 1 black female: 2 red 

 males : 1 red female : 1 dun female : 1 yellow 

 female. 



While the number of offspring is too small 

 on which to base any conclusion as to propor- 

 tions, it will be noted that all so far obtained 

 fall in liae with the expectations as to color 

 and sex. 



The foregoing may provide an explanation 

 of the interesting observations of E. M. 

 Strong- on the sex of ring-doves,'' and those of 

 Bonhote and Smalley (loc. cit., p. 61Y, foot- 

 note), as well as possibly those of Whitman 

 reported by Riddle." 



[P. S., July 22, 1912. Since the foregoing note 

 went to press there has appeared in the June, 1912, 

 number of the Journal of Genetics (Vol. 2, No. 2, 

 p. 131) a paper by Mr. E. Staples-Browne, in 

 which the relation of blue and silver to sex is 

 amply demonstrated.] 



Leon J. Cole 



THE INTERTUBERCULAK OR BICIPITAL FORAMEN OP 

 THE HUMERUS OF THE GUINEA-PIG 



The upper extremity of the humerus of the 

 guinea-pig often has an unusual, probably an 

 unique, structure. A broad and thick bridge 

 connects the large and small tubercles and 

 converts the intertubercular sulcus into a 

 foramen through which passes the tendon of 

 origin of the m. liceps. At the last meeting 



* Science, N. S., Vol. 33, p. 266, 1911. 

 » Science, N. S., Vol. 35, p. 462, 1912. 



of the Association of Anatomists, I reported 

 that among twenty skeletons studied, four 

 humeri from three individuals, two males and 

 one female, were found which had this pecul- 

 iar structure. Recently, through the kind- 

 ness of Professor Castle and Dr. Detlefsen, 

 of the Bussey Institution, I have been allowed 

 to study their large collection of guinea-pig 

 skeletons and was surprised to find the re- 

 markable prevalence of the intertubercular 

 foramen. Out of a total of 125 humeri, 17, 

 13.6 per cent., have complete foramina. Be- 

 sides these 23 others, 18.4 per cent., have 

 nearly complete bridges over the intertuber- 

 cular sulci. In six instances, this bridge is 

 formed by a small supernumerary bone which 

 is wedged in between the great and small 

 tubercles; in the others, by small acute proc- 

 esses which project toward each other from 

 the adjacent sides of the tubercles. One or 

 two similar but smaller processes occur upon 

 50 humeri, 40 per cent, of the total number, 

 the remaining 35 bones, 28 per cent., having 

 no indication of the foramen. 



All of the skeletons used are of adult or 

 subadult animals, but as the growth of the 

 guinea-pig continues long after sexual matur- 

 ity, possibly throughout life, it is probable 

 that had the animals been older, an even 

 larger proportion of complete foramina would 

 have been present. 



In all cases, the foramen has the same char- 

 acter. The upper edge of the bridge is con- 

 vex, its lower edge concave. The canal-like 

 foramen is narrow above, but rapidly widens 

 below and terminates in an oblique, flaring 

 and funnel-shaped mouth which is surrounded 

 by a rough, slightly elevated, lip. 



It seems impossible to correlate the occur- 

 rence of the intertubercular foramina with 

 sex, age or muscular development. Foramina 

 do not occur in immature animals, but, on the 

 other hand, they are absent in certain very old 

 animals (three or four years old) and further- 

 more they are occasionally present upon one 

 side only. 



Leonard W. Williams 



Haevabd Medical School 



