REMAKKABLE SPECIES OF ECIITÜEOIDS. 49 



marking disappears altogether. The ventral concavity of the 

 jiroboscis deepens towards the base, so that in this region the 

 organ presents the form of a half-tube semicircular in cross- 

 section. 



The cylindrical body proper measures 30-35 cm. in length 

 and transversely 2.5 cm. across. The general color is a brownish 

 red. Of the paler colored, equidistant, longitudinal lines due to 

 special thickenings of the longitudinal muscle layer of the body- 

 wall, there are ten, instead of five in which number they occur 

 in Th. tœnioides. The dermal papillœ are in all respects similar 

 to those of the species just referred to. They are largest and 

 most closely aggregated in the anterior and the posterior parts 

 of the body. Where the circular muscles of the body-wall has 

 strongly contracted, there appear on the surface small lenticular 

 outbulgings of the skin, regularly and closely arranged in long- 

 itudinal rows in the zones between every two of the ten pale-colored 

 longitudinal lines. In the anterior half of the ventral side of 

 the body, there are seen, in the living state, an indefinite number 

 of deep red flecks which incessantly move about, at the same 

 time changing their size (fig. 4). These flecks are brought about 

 by the coming in contact of parts of segmental organs, which 

 are of a milky white color, with the reddish inner surface of the 

 body-wall. The two ventral hooks are situated a short distance 

 — about 1.3 cm. — behind the base of proboscis. They are moder- 

 ately large and slightly curved needles of a brownish yellow 

 color. No anal hook is present. 



Some Points of the Internal Structure. — All the longitudinal 

 lines visible on the outside, excepting the one which runs in the 

 mid-ventral line and is superposed by the nerve-cord, appear on 



