Nos. IAND2.] COTYLASPIS INSIGNIS. 25 



part, but in some cases I do not find anything in it, and in other 

 instances there is a sort of concretionary structure hke that in 

 the figure. As this is not found constantly it can hardly be con- 

 sidered an essential feature of the organ. The wall of this cham- 

 ber is composed of the two coats; next the space a coat which 

 has somewhat the appearance of both a cuticle and an epithelium. 

 It contains nuclei but cell boundaries are wanting and the sub- 

 stance does not look actively protoplasmic. I am inclined to 

 consider it a degenerated epithelium. On the outside of this layer 

 distinct longitudinal muscular fibers are visible in many sections. 

 There do not appear to be any circular muscles here. Beyond the 

 upper part of the organ I find a mass of non-staining fine parallel 

 threads which have the same appearance as the nerve trunks in 

 other parts of the same series. Monticelli indicates a similar struc- 

 ture in his figure 8 of plate XXIII. of Cotylogastcr, and re- 

 gards it as a retractor muscle, but I am not able to recognize any 

 muscular fibers in it, though these are demonstrated in other parts 

 of the organ very clearly, and this speaks against that identifica- 

 tion. ]\Ionticelli, in his idealized figure, indicates that the upper 

 part of the organ is entirely closed. I do not agree with this 

 opinion, since I can, in certain sections, trace a direct continuation 

 from the surface opening up to the cavity of the upper organ, and 

 besides, as stated above, I sometimes find concretions in the cavity 

 of the upper organ as in Cotylogastcr (Fig. 13), and at other 

 times do not. The latter I attribute to escape of these, and this 

 implies a passage to the exterior. 



jMonticelli suggests that this organ in Cotylogastcr is a tactile 

 organ and that it is used to determine by pressure if a surface is 

 a suitable one for the adhesion of the ventral sucker. Voeltzkow 

 also reports the organ in Aspidogastcr and suggests that it is there 

 an organ of touch. Xickerson finds a similar organ in Cotylo- 

 gastcr occidentalism and he takes a dififerent view of its function and 

 inclines to the opinion that it is not a sense organ but a secretory 

 organ. I have not as yet ascertained any facts .which decide the 

 matter. The large amount of muscular tissue in the organ indi- 

 cate its capacity for protrusion, though I have never been able to 

 get a view of it protruded, and the nerve going to it indicates 

 tactile function, but on the other hand it does not have the 



