584 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 58. 



tions only in favorable mounts (plate 29, fig. 7). Anteriorly the 

 muscular esophagus ends abruptly in the buccal cavity. In end view 

 the two latero- ventral and the dorsal muscular fields of the esophagus 

 surround a triradiate lumen. The dorsal field is provided near its 

 anterior end with a tooth equal to about half the diameter of the 

 esophagus (plate 29, fig. 8). The tooth probably contains the outlet 

 of a gland, indicated by a large nucleus at its base. The two ventral 

 fields are each provided with a smaller tooth. The whole anterior 

 end of the esophagus is evertable through the mouth, and when it is 

 everted the teeth may be seen to point forward and outward (plate 

 29, figs. 2-4). The nerve ring is large and usually located near the 

 middle of the esophagus (plate 29, fig. 9). 



The number of longitudinal cuticular ridges, usually stated to be 

 18 to 22, or even 26, was found to depend on the diameter of the 

 body (plate 29, figs. 9-14; plate 30, fig, 15.) The ridges occupy two 

 fields, dorsal and ventral, arising at the anterior end as two single 

 median ridges. The ventral median ridge is interrupted by the 

 opening of the excretory pore. The other ridges arise on both sides 

 of the median ridges as the body increases in diameter. The median 

 ridges always remain highest and the lateral ones lowest. The 

 median ridges arise directly over the dorsal and ventral hypodermal 

 thickenings, but there are no ridges corresponding to the lateral 

 thickenings of the hypodermis. Alternating with the four lateral, 

 dorsal, and ventral lines, or hypodermal thickenings are four muscu- 

 lar tracts. Each tract at the nerve ring contains two muscle cells, 

 but later contains four or more. 



The vulva was found to be a transverse slit in all of the species 

 examined. The ovijectors in the species with short spicules are very 

 short and stout, as described in detail by Maupas and Seurat (1912), 

 while in the forms with long spicules they are much elongated. 



EXCRETORY APPARATDS. 



The excretory apparatus deserves special mention on account of 

 its great development (plate 29, figs. 10-14.) The excretory pore is 

 large, being easily visible in toto preparations, located at the base of 

 the esophagus and opening through the median ventral ridge, as 

 already stated. The excretory tube branches almost immediately, 

 each branch passing diagonally back to its corresponding lateral 

 field. There soon arises in connection with each of these fields a 

 vascular thickening, which increases in diameter posteriad and be- 

 comes more or less dissociated from the lateral field to form a pyri- 

 form renette or cervical gland with one huge nucleus at its middle. 

 The two renette cells occupy about one-fifth of the body length, one 

 extending slightly farther back than the other. Throughout their 

 extent the excretory tubes can not be traced, but behind them the 



