TAPES. 389 



tendency to imbrication. The variety of colouring is almost 

 infinite in patterns, but is generally compounded of pencil- 

 lings of pink, or various shades of dark or ruddy flesh- 

 colour and white. Very rarely it is of a pure milk-white, 

 and devoid of all painting ; more usually the darker are 

 the prevailing tints from the crowded masses of zigzag lines 

 which cover the surface so closely that the white is only 

 visible at the triangular interstices of this net-work, or 

 in the shape of two more or less broad ray-like streaks. 

 One of these latter, is ordinarily placed at about one- third 

 the distance from the anterior end (and this is almost per- 

 pendicular) ; the other, which is very oblique, along the 

 ordinary site of an umbonal ridge. Occasionally, where 

 the entire surface is thus reticulated, or assumes an uniform 

 or slightly mottled tint from the extreme minuteness of the 

 linear zigzags, there are from two to four rays which are 

 chiefly manifested by there being a lesser preponderance of 

 dark markings upon those areas, and sometimes too by the 

 occurrence of angulated spots of a deeper shade than the 

 prevailing colour ; these last are occasionally confluent, and 

 run alongside of the white or paler rays. Occasionally the 

 rays are wholly composed of more or less interrupted ob- 

 scure markings of a deeper tint than the almost uniform 

 ruddy hue of the ground. 



The ventral margin is convex or subarcuated, rising at 

 each end, but particularly in front : the declination of the 

 front dorsal is short, moderate, and straight, or but slightly 

 retuse, that of the hinder one is very trifling, and almost 

 rectilinear in the young, becoming stronger and more convex 

 with increasing age. The anterior side, whose extremity is 

 attenuately rounded, varies from occupying one-third, to 

 only making one-fifth, of the entire length : the posterior 

 end, which, in the young, is somewhat biangulated, (the 



