COAT CHARACTERS IN GUINEA-PIGS AND RABBITS. ^7 



When the rough coat character is best developed, rosettes are seen 

 around the following paired centers: (i) The eye, (2) a point immedi- 

 ately behind the ear, (3) the shoulder, (4) a point dorso-lateral on the 

 side of the body about midway between shoulder and hip, (5) the hip, 

 (6) the groin, (7) each of the single pair of mammas ; and from two 

 unpaired centers, viz, (S) the middle of the forehead, and (9) the navel. 

 The direction of the hair is also reversed on the toes. 



In crosses between pure rough individuals and smooth ones, the rough 

 character is dominant, all the young being rough and ordinarily having 

 the rough character as fully developed as in the rough parent. But 

 certain smooth animals, which may properly be described as prepotent, 

 produce offspring which show a weakened condition of the rough char- 

 acter, some of the typical rosettes being either less well developed than 

 in the rough parent or wanting altogether (see PI. 6, fig. 12). Such 

 offspring may be called partial rough. They frequently transmit the 

 rough character in its full intensity to their offspring, as we shall pres- 

 ently see, though they themselves are only partially rough. 



Repeated crossing of rough animals with prepotent smooth ones 

 results in further weakening of the rough character until it is almost 

 eliminated. Successive stages in this weakening process may be recog- 

 nized, which are about as follows : 



Condition A : The fully developed rough character as above de- 

 scribed (see PI. 2, figs. 3 and 4). 



Condition B : Forehead and shoulder rosettes have disappeared, hip 

 and side rosettes either fuse into an obliquely longitudinal dorso-lateral 

 part sloping downward posteriorly, or the hip center disappears entirely. 



Condition C (PI. 6, fig. 12) : The only conspicuous rosettes are the 

 side rosettes, though the ear rosettes may usually be found by careful 

 examination ; between the ear and side rosettes a ridge runs obliquely 

 downward and backward across the body from the shoulder ; there is 

 likewise a median dorsal crest ; the hair is reversed in direction on the 

 hind feet, and turned laterally but not reversed on the front feet. 



Condition D : Only a single pair of rosettes, the side rosettes, persist ; 

 a mid-dorsal crest extends from the head back to the rump ; hair on the 

 feet as in Condition C, or that of the front feet straight. 



Condition E : No rosettes, a mid-dorsal crest from the head back- 

 ward, perhaps half the length of the body ; hair of toes reversed on 

 hind feet only or not at all. 



Condition F : No rosettes or crest. Hair reversed on hind feet only. 



It must not be understood that these steps are necessarily taken one 

 at a time. The original cross between rough and smooth may lead 

 directly from Condition A to Condition D, when the smooth parent is 

 very prepotent. 



