REMARKABLE SPECIES OF ECHIUROIDS. 27 



cord. Of this mesentery the parts immediately adjoining the 

 crop wall form a gland-like structure of a reddish brown color 

 (fig. 37, gLs.), 



The crop is followed by the mid(jut (fig. 23, m.g.). This 

 is about three times as long as the former. The inner surface 

 is put into closely set transverse wrinkles, instead of having 

 papillœ. The tube bends forwards and backwards several times 

 so as to form irregular W-like loops. It is not supplied with a 

 mesenterial membrane but is fixed to the body-wall by a series 

 of numerous muscle-threads, which on the whole are arranged 

 in the manner of a mesentery. In all the specimens examined, 

 the crop was found to be infested by an abundance of a Sporo- 

 zoau parasite. 



The boundary between the crop and the next following 

 section, the intestine, is externally marked by the anterior end 

 of the collateral intestine or the siphon {c.i.). The intestine 

 proper is a comparatively wide (4-7 mm.), complexly winding 

 tube of a great length. When straightened out, it may measure 

 nearly li meter in length. The inner surface is thrown into 

 small transverse folds, which can be seen from the exterior through 

 the thin wall. Like the preceding part of the digestive tract, 

 the intestine is held in position by a mesentery-like series of very 

 numerous muscle-threads. It may be distinguished into two parts. 

 The first part {in.), making up about two-thirds of the length 

 of the entire intestine, is accompanied by the collateral intestine 

 {c.i.) ; it takes an irregularly winding course down to nearly the 

 posterior end of the body-cavity and then turns round forward, 

 to pass over into the second part at a certain distance. The 

 second part {in.) all along exhibits the siphonal groove {s.g.), 

 brought into view owing to the absence here of the overlying 



