1907.] NATURAL SCIENCES OF PHILADELPHIA. 115 



"muscular appendage," "Pharanx," and "Pliarangealtasche" by 

 different authors. On account of its brevity and definiteness I prefer 

 to use the earlier one of "proboscis" ("trompe," Hallez; "Riissel/' 

 Korschelt). The proboscis of D. conklini lies just behind the mouth, 

 and in side view presents a reniform outline, its concave surface 

 directed forward and applied to the posterior wall of the ascending 

 limb of the oesophagus (fig. 23). In cross section (figs. 4, 5, and 23, pro. 1 

 and jyro. 2, and fig. 30) it is elliptical, the long axis of the ellipse lying 

 transversely. The greater portion of this organ lies within the body 

 cavity between the two limbs of the oesophagus, and practically filling 

 up this space. The anterior and more pointed end of the proboscis 

 {-pro. 1) projects into the pocket-like cavity opening between the inner 

 and outer lips, and is covered by a reflection of the cuticle which lines 

 the cavity. This portion of the proboscis also differs histologically 

 from the remainder, being composed of cells substantially similar to 

 those of the oesophageal wall, but slightly darker and less distinctly 

 granular, which pass over, on the dorsal side, into those forming the 

 inner lips, as shown in fig. 23. Beneath the fold of cuticle which con- 

 nects the proboscis with the outer lips, in the same figure (23), may be 

 seen a network of protoplasm which finally unites with the epithelium 

 of the outer lips (o.Z.). This network encloses a nucleus, in the section 

 figured, and is, together with the tip of the proboscis, as well as the 

 inner lips {i.l.), merely a continuation of the epithelium forming the 

 oesophageal wall. Laterad of the midline this epithelium is clearly 

 seen to be continuous over the whole of the pocket, from the upper 

 lips to the posterior margin of the mouth. This continuity of the 

 oesophageal epithelium is still more plainh^ seen in D. tcBniatus (Harmer, 

 1889), and in D. vorticoides, as seen in the figures of Schimkewitsch 

 (1895). In both these forms it passes unbroken over the proboscis 

 to the posterior border of the mouth. This is especially well seen in 

 Schimkewitsch (Taf. VI, fig. 37). The remainder of the proboscis, that 

 is, all of the organ behind the pointed tip, presents a histological 

 structure which is extremely curious. This peculiarity of structure 

 has been either entirely misunderstood by previous ^mters or passed 

 over with scant notice. A careful study of sections shows that the 

 part in question, constituting the major portion of the proboscis, is 

 divided into about thirty narrow chambers by as many transverse 

 cuticular partitions (fig. 23, fro. 2), regularly placed from one to three 

 micra apart. These partitions bear on each of their two surfaces a 

 single layer of slender fibrillse, of uniform diameter, and having the 

 same general appearance and staining reaction as muscle fibres (figs. 



