of the Genus Martes. 291 



saying, from an examination of the above specimens, that the yellow- 

 breasted specimen is merely the young of the other ; and that the Com- 

 mon Marten retains a yellow tinge on that part until after the first, 

 or perhaps until after the second winter. My yellow-breasted speci- 

 men had been obtained in September, and was not, I should think, 

 from the state of ossification, an animal born during the foregoing 

 summer ; the other specimens were all procured during winter, are 

 all larger, and have the colouring on the breast not nearly so deep 

 as in the one just mentioned. Had I not, however, seen a cranium 

 in an intermediate state, I should certainly have supposed that the 

 skeletons were those of two distinct species. 



I do not, however, by any means intend to affirm that no second 

 species exists in the British Isles, as my specimens were all obtained 

 from a limited district in North Wales, but nevertheless presenting 

 all the characteristics of the supposed British species. 



The numbering of the vertebrae and ribs in both skeletons are the 

 same ; but I give them here for the sake of offering other persons the 

 opportunity of comparing them with any skeletons that they may have 

 belonging to the genus. 



Cer. 7, dor. 14, lum. 6, lac. 7, caud. 15, ribs 14 pair. 



The form of the different bones, with the exception of some of 

 those composing the crania, do not present any remarkable differ- 

 ences ; those, however, of the smaller skeleton present many marks 

 of immaturity. The following admeasurements will show the dis- 

 parity in size. 



Larger skeleton, Smaller skeleton, 

 or adult. or young. 



Inches. Inches. 



Length of tibia 3y ^ 3 



of femur 3^ 2^ 



humerus 2^- 2 J 



ulna 2j% %tu 



scapula lf% Iyq 



Breadth of ditto lf^ l T 4 o 



Length of cranium 3-^ 3 



Breadth of ditto 2 lf% 



Length of pelvis 2^ 2-^ 



Breadth of ditto, at acetabular cavity 1-^y lyo 



In the cranium of the younger specimen, the tuberose process to 

 which the ligamentum nuchse is attached appears the most promi- 

 nent, and the crest over the vertex, on which the temporal muscles 

 arise, is narrower than in the adult. The greater degree of promi- 

 nence in the tuberose process- in the young, may be explained by 

 the crest running from it over the vertex as it becomes broader, 

 filling up the indentation on each side ; thus this apparently greater 

 degree of prominence merely proceeds from an incomplete state 

 of ossification in the surrounding parts. 



The next most striking point of difference in the cranium, is that 



u 2 



