436 Thos. H. Montgomery, Jr. 



band extending from near the anterior end to the spinnerets; at the 

 antero-dorsal boundary a transverse white band that extends 

 down on both sides; on each side behind the latter are two obhque 

 white bands; all these bands are narrowly edged with black. On 

 the venter there is a broad white mark which is on each side bor- 

 dered by black, and on each side of the spinnerets are three oblong 

 black spots. The remainder of the abdomen is pale brownish 

 flecked with white. In one male there was a red hne inclosed 

 within the dorso-median white band of the abdomen, and deep 

 black filling all the spaces between the abdominal white bands.* 



The males in the instar just preceding the adult stage have 

 the abdomen larger and more rounded, the legs proportionately 

 thicker, and the abdomen colored like the young female, namely, 

 dull or deep black, with a medio-dorsal white band including a red 

 one, an arched transverse white band anteriorly, two oblique 

 narrow white bands on the sides, and a broad white band on the 

 venter. 



The newly hatched of both sexes are yellow with black stripes 

 on the abdomen as follows: two narrow parallel stripes along the 

 dorsum, two broader ones on the venter, and three (often broken) 

 oblique stripes on each side. Thus the color of the adult male 

 retains the color pattern of the young much more than does the 

 adult female, for the latter becomes to great extent deep black. 

 In color, size and activities the male is decidedly more embryonic. 



So far all observers, with the exception of Doumerc, have held 

 the newly hatched of spiders to be sexually indistinguishable. 

 At that period the genital plates are quite simple, and the pedipal- 

 pal tarsus of the male is not different from that of the female. On 

 sectioning the spiderlings of L. mactans I could not distinguish 



* I have described mactans rather more fully than might seem necessary for our present purposes, but 

 this is called for on account of the present confusion with regard to the American species. For this 

 reason I will give briefly the characters in which geometricus differs from mactans. The male of geo- 

 metricus differs only in having two pairs of black spots just behind the middle of the dorsum. The 

 female of geometricus differs from the female of mactans in having the dimensions of all parts of the 

 body slightly smaller but the abdomen much smaller, the legs pale colored with dark rings; in geometricus 

 also the general color of the abdomen is pale brown, more rarely black, and always marked by lighter 

 markings on the dorsum and sides. Further, the cocoon of geometricus has the surface beset with 

 numerous slender, cylindrical villi, each from i mm. to 1.5 mm. in height, while the cocoon of mactans 

 is quite smooth. L. geometricus occurs in California and Jamaica. 



