4 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.66. 



ventral ray is the largest of all. It is very stout basally and runs 

 nearly parallel with the externo-lateral for about half its length, 

 being widely separated from the ventro-ventral. The distal half, 

 which tapers markedly, performs a wide sweeping curve forward 

 until it comes very near to the ventro-ventral at the iimer limit of 

 the fluted bursal margin. At this point it bends outward again, 

 so that the tips of the two ventral rays come to lie parallel in the 

 fluted margin of the bui^a, in an obtuse angle formed in the bursa 

 at this point, directly opposite a similar obtuse angle formed where 

 the medio- and postero-lateral rays terminate. These latter two 

 rays are of moderate size, approximately equal, parallel, and curving 

 dorsally. The externo-lateral ray is much larger than the other 

 lateral rays, curves toward the ventral rays, and terminates in a 

 sharply constricted finger-like tip at a point on the margin of the 

 bursa about midway between the ventral and the other lateral rays. 

 The small but stout externo- dorsal ray curves dorsally and ter- 

 minates in the margin of the bursa about midway between the tips 

 of the postero and medio-lateral rays and the junction of dorsal and 

 lateral lobes. 



The small dorsal lobe (fig. 8) is of very peculiar structure. It 

 is overlapped, as Graybill has pointed out, by the lateral lobes, and 

 is sharply marked off' from them. It is supported by a single dorsal 

 ray which forks distally into two bifurcated tips. Near the middle 

 of its length a pair of branches are given off' which curve ven- 

 trally, pass through a minute foramen, and enter a vesicular swell- 

 ing as in Cooperia. Ventral to this swelling there is an additional 

 membranous flap, supported by a pair of very minute, delicate par- 

 allel rays. 



In some of the specimens measured the spicules (figs. 9-10) are 

 considerably larger than those measured by Graybill, a number of 

 them varying between 500 and 540 ]x in length with a lateral diame- 

 ter of 50 ^. Although the chitinous portion of the spicules is 

 cleft distally, and terminates in a dorsal and a ventral hook, the 

 spicules can not be said to be cleft, since these parts are connected 

 by a membrane as shown in figures 9 and 10. The ventral hook 

 is the larger and coarser, bending in a medioventral direction; the 

 dorsal hook bends dorsally, laterally, and then distally, ending in a 

 slender point. The membranous expansions at the distal ends of the 

 spicules extend beyond the chitinous hooks. 



A few of the females reach a length of 20 mm. Graybill gives 

 the maximum length as 18.5 mm. He records the maximum width 

 of one specimen as 546 p., but in the Texas specimens the greatest 

 width, of about a dozen specimens measured, was 400 [a, just an- 

 terior to the vulva. At this point there is a marked reduction in 



