137] LIFE HISTORY OF GORDIUS AND PARAGORDIUS—MA Y 17 



The posterior end of the male bears two short, stout prongs (Figs. 8, 32). 

 The length of the prongs varies somewhat, but is usually not much more 

 than half the diameter of the body. Each prong is jdi conical shape with 

 a slight flattening on the inner side. The body attenuates rapidly dorso- 

 ventrally at the base of the prongs so that the diameter of the latter is less 

 than half that of the body (Fig. 24). On the ventral side, a short distance 

 anterior to the bifurcation is a crescent-shaped ridge with the ends of the 

 crescent passing slightly onto the bases of the prongs. I have usually 

 found this ridge to be a broad, open crescent and not U or V-shaped as 

 represented in most of Montgomery's figures. The anus is located a short 

 distance anterior to the middle of the crescent, almost at its very base. 



Color. The usual color is light brown, but specimens vary from nearly 

 white to nearly black and females that have deposited their eggs are gray. 

 When light is reflected in the proper way the cuticula shows a distinct 

 iridescence, very pronounced in females after deposition of the eggs. Such 

 females examined in the sunlight present brilliantly all the colors of the 

 rainbow. Ordinarily the iridescence gives the body of the worm the appear- 

 ance of being longitudinally corrugated. The anterior end is clear white 

 followed by a ring of dark brown which passes rather abruptly into the 

 normal brown of the body. At the center of the anterior white area is 

 often found a black spot indicating the position of the mouth (Fig. 33). 

 Passing backward from the dark ring are two bands, one ventral and one 

 dorsal, slightly darker than the rest of the body (Figs. 26, 27, 28). These 

 bands can usually be traced to the posterior end of the female, but are more 

 difficult to trace in the male. Even there the dorsal line can often be traced 

 to the base of the fork while the ventral line disappears a short distance 

 before the anus. Montgomery does not mention these lines or bands in 

 his description of the species, but I have found them present in all of his 

 material that I have examined as well as in Leidy's material. They are 

 mentioned by Leidy in his description of 1879. In the female the cloacal 

 opening is situated at the center of a dark area, which itself is surrounded 

 by an area slightly lighter than the body color, and around that is a brown 

 circle, the dark color of which passes more or less gradually into the general 

 body color (Fig. 34). In the male the crescent is dark brown, almost black, 

 and there is a small dark area surrounding the anus (Fig. 32). Lighter 

 spots scattered over the body may or may not be present. I have found 

 them on many specimens at Urbana (Fig. 16), but never as pronounced as 

 in Montgomery's specimens from California. 



Cuticula. The cuticula never shows any traces of areoles. Under low 

 magnification it appears to be divided into rhomboidal areas, while higher 

 magnification shows a system of finer intersecting lines (Figs. 4, 5). The 

 white area at the anterior end is of more homogeneous structure. Bristles 

 or hairs are present over the entire body. Montgomery says they are 



