BIRDS— GRADATION OF CHARACTERS. 



429 



become confluent, either in the line of the row — and then they 

 form a longitudinal stripe — or transversely, that is, with the spots 

 in the adjoining rows, and then they form transverse stripes. A 

 spot sometimes breaks up into smaller spots, which still stand in 

 their proper places. 



It will be convenient first 

 to describe a perfect ball- 

 and-socket ocellus. This 

 consists of an intensely 

 black circular ring, sur- 

 rounding a space shaded so 

 as exactly to resemble a 

 ball. The figure here given 

 has been admirably drawn 

 by Mr. Ford and well en- 

 graved, but a woodcut can- 

 not exhibit the exquisite 

 shading of the original. 

 The ring is almost always 

 slightly broken or inter- 

 rupted (see fig. 57) at a 

 point in the upper half, a 

 little to the right of, and 

 above the white shade on 

 the enclosed ball; it is also 

 sometimes broken towards 

 the base on the right hand. 

 These little breaks have an 

 important meaning. The 

 ring is always much thick- 

 ened, with the edges ill-de- 

 fined towards the left-hand 

 upper corner, the feather 

 being held erect, in the po- 

 sition in which it is here 

 drawn. Beneath this thick- 

 ened part there is on the 

 surface of the ball an 

 oblique almost pure-white 

 mark, which shades off 

 downwards into a pale- 

 leaden hue, and this into 



yellowish and brown tints, which insensibly become darker 

 and darker towards the lower part of the ball. It is this 

 shading which gives so admirably the effect of light shining on 

 a convex surface. If one of the balls be examined, it will be seen 

 that the lower part is of a brown tint and is indistinctly sepa- 



if 















* ,'. 



Fig. 57. Part of secondary wing-feath- 

 er of Arg-us pheasant, showing two 

 perfect ocelli, a and b. A, B, C, D, 

 &o., are dark stripes running ob- 

 liquely down, each to an ocellus. 



[Much of the web on both sides, es- 

 specially to the left of the shaft, has 

 been cut off.] 



