32 AXTARCTIC MARINE 



is unarmed, though a little in front of it there are a very few papilla-like setae. 

 The three more or less elongated saccate caudal glands extend in a loose tandem 

 in front of the anus a distance five times as great as the corresponding body- 

 diameter. Their distinct and somewhat tortuous ducts widen to three separate 

 ampullae so as to fill the middle of the tail. The vulva is slightly depressed and 

 is rather inconspicuous. The vagina extends inward at right angles to the ven- 

 tral surface about halfway across the body. Both before and behind the vulva 

 there are well developed unicellular glands. Each of the two straight uteri is 

 about seven times as long as the body is wide, and contains a row of five or six 

 eggs in the specimens examined. The rather thick-shelled eggs are three-fourths 

 as long as the body is wide, and nearly as wide as long. Owing to their pressure 

 on each other the eggs take on a more or less rectangular contour. The broad ova- 

 ries reach two-thirds the way back to the vulva, and contain scores of discoid 

 ova, arranged more or less in single file. 



The anus of the male is broadly elevated. The tail of the male has a compli- 

 cated sexual armature. Near the anus on the anterior fourth of the tail there 

 are six stout, stiff, conoid, somewhat blunt, ventrally submedian setae on each 

 side, the longest of which, those nearest the anus, are nearly as long as the cuti- 

 cle is thick, and the smallest of which, the hindermost, are very small. The pre- 

 anal setae are arranged in ventrally submedian rows, of which the individual 

 setae are much nearer together posteriorly than anteriorly. Between the anus 

 and the single ventral median supplementary organ there are ten of these setae; 

 between the latter and the posterior member of the ventrally submedian rows 

 of supplementary organs there are two of these setae; between the ultimate and 

 the penultimate members of the submedian series there are also two. Thence 

 forward between any two members of the submedian series there is but a single 

 seta. In all, therefore, there are about seventeen of these setae on each submedi- 

 an line in front of the anus. In addition there are two very inconspicuous, papil- 

 loid, tapering, acute, lateral setae near the terminus. The lateral fields, one-third 

 to two-fifths as wide as the body, are composed of several rows of cells among 

 which are placed glandular, saccate cells, of two or three times as great diameter, 

 connected with the exterior by means of pores in the cuticle. The relative num- 

 ber and position of these glandular cells may be judged to a certain extent from 

 the fact that in the female near the vulva three of these large saccate cells are 

 separated from each other by spaces about equal to their own diameter. These 

 cells are entirely similar to those described by Jaegerskiold, de Man, and other 

 authors, who have made observations on species of Thoracostoma. The distinct 

 cells connected with the more or less broad and oblique nerve-ring are arranged 

 into rather distinct groups and are a prominent feature of the middle half of the 

 neck. 



The stout, blunt, yellowish spicula, cephalated by a very slight constriction, 

 are arcuate in the distal half, and are one and three-fourths times as long as the 

 anal body-diameter. At the widest part, a little in front of the middle, they 

 are about one-fourth as wide as the corresponding part of the body. From the 

 widest part they taper gradually to the distal ends, but taper more suddenly 

 toward the proximal ends, which lie opposite the body-axis and have a width 

 when viewed in profile about twice as great as the thickness of the adjacent cuti- 

 cle on the dorsal side of the body. The difference between the anterior and pos- 



