344 NEW YORK STATE MUSEUM 



on the spine of one surface, a spine of the other surface may usually be 

 detected close by, though somewhat out of focus (pi. ii, fig. i b^ b). 

 This fact will be taken for granted in the following description, and no 

 farther mention of it will be made. 



The plates, which are called also gland hairs, or, by Green, squames, 

 extend, in general, nearly parallel to the main axis of the body, and 

 appear soft and for the most part clearer and broader than the spines, 

 and lack the bulbous base, but they assume various forms and may be 

 either simple and hair-like, or forked or fringed at the tip. Varying out- 

 lines are shown in figure i at c, c, c, c. They are often hard to detect 

 definitely, as they are transparent and sometimes disappear in clearing^ 

 either through actual dissolution or by attaining the same refractive index 

 as the mounting medium. Their function is probably connected with the 

 excretion of the scale. 



The margin is often cut in or incised. In the following species two 

 pairs of incisions can usually be detected, the second being comparatively 

 inconspicuous (pi. ii, fig. i d, d). 



Beside the incisions are heavily chitinized places which appear dark 

 in the cleared specimens. These have been spoken of by Prof Com- 

 stock as the "thickened margin of the incisions," but by later writers 

 are more frequently termed *' chitinous processes " ; and this phrase I shall 

 use, applying it also to the thickenings which sometimes appear on the 

 inner margins of the median lobes. These last have been spoken of as 

 " club-shaped processes " ; but, as this term has also been appHed to 

 other organs, it seems wiser to discard it, simply giving definiteness to 

 the term " chitinous processes " by some phrase of location. Different 

 forms of these processes are shown in plate ii, figure i ^, e, <?, e. A gen- 

 eral thickening of the body wall inward from the lobes frequently occurs, 

 but is usually rather indefinite in appearance (fig. i/). 



As the insect is so much flattened, there are practically but two aspects, 

 the dorsal and the ventral. In a well cleared specimen the organs of both 

 sides are visible at once, yet by careful focusing can be distinguished. 

 In plate ii, figure i, the superficial organs of the ventral side are 

 represented in the left half of the figure; those of the dorsal side on the 

 right. Perhaps the most important of these superficial organs are those 

 which appear on the ventral side of the body as groups of distinct circu- 

 lar organs with several tiny perforations in the middle of each. They 

 are the openings of glands which presumably secrete the covering of the 

 eggs, and have been variously named the spinnerets, the paragenital 

 glands, the circumgenital glands and the ventral grouped glands. I sh^U 



