1903.] NATURAL SCIENCES OF PHILADELPHIA. 377 



an annular fold composed of a more thickened cell layer; it is shown in 

 oblique ventral view in fig. 11, on lateral view in fig. 9, and on dorsal 

 view in fig. 10. The drawings show that this ring fold bears ciha along 

 the anterior border of its ventral half, a tuft of longer ciha on each side, 

 while the margin of its dorsal half has no cilia. Only this diaphragm 

 bears ciha, and none are found upon the walls of the infundil^ulum and 

 vestibulum. 



By a narrow aperture there follows upon the vestibulum the oesopha- 

 geal tube {Oes. T.), the distal end of which projects freely without 

 attachment into the cavity of the proventriculus. This is an elastic 

 tube that beats rapidly in many dilations and therefore probably pos- 

 sesses a musculature of its own; I could not determine nuclei in its 

 wall. The proventriculus (Prov.) is the largest portion of the ahmen- 

 tary tract, its wall composed of a single epithelium of large cells with 

 distinct nuclei, and lined internally by a cuticula. In this posterior 

 part lies the mastax, concerning which it will suffice to refer to fig. IS, 

 a dorso-posterior view. Gosse was wrong in considering it to be rudi- 

 mentary, for it has well developed unci and manubria, fulcrum and 

 rami. The stomach (Stom.) is a rounded, dorsally placed sac lined by 

 large cells which bear numerous long ciha. The posterior intestine 

 (P.Int.) follows, lined by a flattened epithelium without cilia and with 

 distinct nuclei; and behind it a very short rectum opening into the 

 cloaca (CL). 



A single pair of large stomach glands {Stom.GL, figs. 9, 10) are present, 

 each latere- ventral at the junction of proventriculus and foot, and each 

 containing several nuclei. 



Musculature. — The following longitudinal visceral muscles run from 

 the foot through the body cavity of the trunk to attach themselves to 

 the bases of the arms of the corona (figs. 9-11). One pair to the dorsal 

 arm, extending to its outer sphincter muscle. A pair of dorso-lateral 

 muscles, each of which inserts anteriorly on the thickened hypodermal 

 ring of the corona at the junction of the dorsal with a lateral arm. 

 And a pair of ventro-lateral muscles, each of which, when reaching the 

 thickened hypodermal ring of the corona, divides into two branches 

 which pass forward to the outer sphincter muscle of the coronal arms. 

 Thus I find only three pairs of longitudinal muscles. All these muscles 

 have their muscle bodies with nuclei contained in the foot. Of the 

 circular hypodermal musculature, there are a large number of dehcate 

 sphincters in the foot and trunk region, and at the anterior end of the 

 corona two sphincter muscles of large size (Sph.C. I and //, figs. 9-11). 

 The remaining complicated network of musculature of the corona I have 

 not studied. 



