Nos. IAXD2.] COTYLASPIS INSIGNIS. 13 



Stichocotylc. I found that iron-hsematoxylin stains the muscle 

 fibers very deeply, so that it is possible to remove all the stain from 

 the surrounding tissue and leave them deeply stained in strong 

 relief. I also found that, by keeping living specimens in a weak 

 aqueous solution of methylene blue, the muscle fibers were beauti- 

 fully picked out. A tangential section (Fig. 9) shows the body- 

 wall muscles in position, and discloses a circular layer next the 

 cuticle, under them a longitudinal series and finally oblique fibers 

 running in two directions. The fibers are never close together, but 

 lie with considerable intervals between them in which the cuticle 

 and the parenchyma are in contact. In methylene-blue prepara- 

 tions I could frequently see rounded nucleated cells (Fig. 11) 

 lying beside the muscle fibers, which appeared to be identical .with 

 the myoblasts of Stafford (Fig. 26). In iron-hsematoxylin pre- 

 parations the circular muscle fibers were structureless but in both 

 the longitudinal and the oblique fibers I found an appearance 

 which is indicated in Figs. 9 and 11. In strongly decolorized pre- 

 parations the fiber, 4, a in diameter, could be seen to present two 

 very distinct parts, an unstained portion imbedded in which were 

 deeply stained elongate spots. This structure resembles that found 

 by Nickerson in the longitudinal fibers of Stichocotylc, and indi- 

 cated in his Fig. 16. 



The arrangement of the body-wall muscles is altered at the 

 excretory and genital openings, where the fibers form circular and 

 radial muscles that are used in controlling the movements of these 

 apertures. As already noted there is no oral sucker in connection 

 with the mouth funnel, the body-wall muscles here are arranged 

 in nearly the usual manner, and, not as in the ventral sucker, 

 collected into special masses marked off from the parenchyma by 

 a Umiting membrance. The acetabula of the ventral sucker are 

 due to the arrangement of the muscles there. These have the same 

 structure as in Aspidogastcr and are sufficiently described in Staf- 

 ford's article on that genus. 



The longitudinal and transverse muscular coats of the body-wall 

 are continvied inwards and backwards from the point where the 

 body and the ventral sucker meet in the middle line, and thereby 

 form (Fig. 5, 6, 7) a muscular partition, the diaphragm, which 



