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length; it tapers gradually toward both extremities, the attenuation 
toward the head being slightly more gradual than that toward the tail. 
Torsion of the body. — These specimens present a torsion around 
the longitudinal axis, so that when the head is viewed dorsallj^, the 
anus of the specimen is shown in profile; when the specimen is so 
placed on a slide as to give a ventral view of the anus, the head is seen 
in profile. 
' Head. — The head (figs. 3-5) is rather bluntly rounded, without any 
indication of a cephalic cone. The small terminal, central, circular 
mouth is surrounded by six papillae, which are directed forward. 
Fig. 3. — Head of same; greatly enlarged lateral view, showing the mouth surrounded by two small 
lateral papillae and four larger submedian lip-like papillae; note the lateral line with its two dis- 
tinct rows of nuclei (one dorsal and one ventral), and a third, middle row of less distinct nuclei 
separating the others; note also the longitudinal striation due to the somatic muscles; the darker 
field is caused by the underlying esophagus. 
Two of these papillse are small and latero-median. Four of the papillas 
are submedian and are much larger than the latero-median papillte; 
they bear some resemblance to lips, and frequently show a larger, 
