MUSEUM OF COMPARATIVE ZOOLOGY. 6 



Diesiug, like von Siebold, was incredulous ; in his " System," he says 

 ('50, p. 207), "(Esophagus protractilis multi partitus (proboscides 

 multae Leidy)." Twelve years later, in the "Revision der Turbellarieu," 

 he writes ('62, p. 506), " oesophago multipartito." 



Stimpson ('58, p. 23) in his Prodromus apparently followed Diesing, 

 for he says " oesophago protractili multipartito." 



Recently, Professor Leidy ('85, p. 49) has figured Phagocata gracilis 

 in a popular account of " Planarians." These are the only descriptions 

 of Phagocata I have been able to find. 



Phagocata gracilis, Leidy. 



When viewed from above, the general form of the animal is elongated ; 

 its lateral margins are nearly parallel, being slightly convex posteriorly ; 

 the widest part of the body is in the pharyngeal region. The largest 

 specimens measure 30 mm. in length by 4| mm. in breadth. Anteriorly 

 the sides converge slightly up to about the region of the eyes, where the 

 diameter increases, thus forming the so called head. This bears the 

 lateral auriculate appendages. The lateral appendages are rounded, 

 rather than triangular as described by Leidy; they are continuous with, 

 and in fact form part of, the anterior extremity ; posteriorly, the sides 

 converge to a point (Fig. 20 a). The eyes appear as two elongated oval 

 white spots, with black pigment on the intenial edge. They are situated 

 on the narrow part or "neck." 



Haldeman and Leidy have described the head as being " straight in 

 front." This appearance is seen only when the animal is at rest. It is 

 then much contracted in the direction of its antero-posterior axis, and is 

 usually much distorted ; at such times it often appears as a shapeless 

 black lump, this condition probably being a means of protection (Figs. 

 20 h and 20 c). When in motion the anterior extremity is usually convex, 

 but not always, for it may be straight, sinuous, or concave ; these shapes 

 are only temporary, following each other in quick succession. The head 

 changes its form especially when the animal approaches some object ; 

 for this part of the body is functional as an organ of touch ; that it 

 is suited structurally to be a kind of feeler will be evident from the 

 description of the nervous system which follows. 



Phagocata gracilis has a shiny black appearance when viewed by 

 reflected light, but by transmitted light it is of a greenish gray color. 

 The color may vary from black to a reddish brown on the one hand, or 

 to a light gray on the other. I have seen small specimens which were 



