Lecaniina. 1 79 



The margin of the body bears a more or less distinct fringe of 

 hairs or spines (each arising from a definite tubercle), which may 

 be simple and pointed {fig. 6) ; dilated and frayed or fimbriate 

 {figs. 4, 5) ; spiniform {fig. 3) ; or flabelliform {fig. 7). These 

 differences may serve as characters for the separation of this 

 somewhat unwieldy genus into sections. 



The stigmatic spines (usually three) are attached dorsally at 

 the base of each stigmatic cleft. They may be sharply pointed or 

 bluntly rounded. The median spine is often considerably longer 

 and stouter than the other two. 



There is often a widely separated submarginal series of small 

 tubercles, which appear to be of a glandular nature (//. LXXX., 



fig- 3)- 



The eyes are of a very rudimentary character, usually con- 

 sisting of a small black pigmented spot situated in an ill-defined 

 clear space (//. LXI. fig. i-a). In old examples the eye-spots 

 may be obliterated by the thickening and darkening of the 

 chitinous derm. Their position may be close to, or at some 

 distance from, the margin. 



The plates of the anal operculum are typically triangular 

 {fig. 11), though occasionally they assume a semicircular outline 

 {fig. 12). Their form and size afford good specific characters. 

 These characters do not vary with the size of the individual, but 

 are practically constant for each of the several stages. For con- 

 venience of description, the line of attachment of each scale may 

 be called its dase {fig. ii-b) : the inner edge being the side of the 

 triangle that is normally in apposition with the corresponding edge 

 of the opposite scale {fig. ii-c): while the third side may be 

 termed the o?i(er edge {fig. i i-a). The angle formed by the inner 

 and outer edges may be known as the apex {fig. ii-a); the outer, 

 {b), and vmer {c) angles being formed by the base with the outer 

 and inner edges respectively (//. UXl. fig. 11). In the semi- 

 circular form of plate, the base and outer edge form a continuous 

 curve, and the outer angle is lost. The apex of each plate usually 

 bears three small hairs or spines. 



The action of the setiferous anal ring has been described 

 amongst the characters of the family Lecaniince. The so-called 

 anal ring consists of a pair of curved chitinous plates encircling 

 the actual anus, which is situated at the inner end of an eversile sac. 

 Each of these plates bears three or four long stout hairs, so that the 

 anal ring is said to bear six or eight hairs, as the case may be. 



BB 



