2 Art. 4 -S. Goto and II. Kikuchi : 



thick, especially in its hinder one-third, where it is nearly cylin- 

 drical in form. We may distinguish three portions of it, the 

 anterior, the middle and the posterior, or caudal. The middle 

 portion contains the vitellarium, while the anterior and posterior 

 portions are free of it and are exceedingly contractile in life. The 

 anterior end of the body is more or less 4-lobed, and these lobes 

 can be protruded in the from of as many papillae or tentacle-like 

 processes, at the top of which open the dermal glands to be 

 described later» The hind end of the body is simply rounded off 

 and the caudal disk is not well defined from the surrounding 

 parts; in fact we have seen it well delimited only once in the 

 fairly numerous cases that have come under our observations, 

 when it was somewhat reniform with the hilus turned backward. 

 The caudal disk bears a pair of more or less centrally placed hooks 

 with a connective, and seven marginal pairs, which are larger than 

 the former, a condition which appears to obtain in none of the 

 species of Dactylo gyrus described so far. The central hooks are 

 represented in fig. 3, a; each consists of a comparatively stout, bifid 

 body and a curved, sharply pointed claw, the one passing into the 

 other without any sharp demarcation; the hoop is situated at the 

 boundary of the two portions and is crescentic in shape. The 

 transverse connective is just perceptibly curved and thickened at 

 both ends. A strong retractor muscle is attached to each bifid 

 und of the central hooks and a number of much smaller muscles 

 to the connective, as shown in the figure. The marginal hooks, 

 all of the same size and form, are lightly curved and consists each 

 of a comparatively thick, club-shaped body and a small claw 

 distinctly set off from the former (fig. 3, b); the body is hollow and 

 is filled by a substance which stains well with haematoxylin. 

 To each marginal hook are attached some protractor and retractor 

 muscles. The marginal hooks are arranged on the caudal disk in 

 such a way that one of the pairs occupy nearly the centre of the 

 disk, a second closely in front of the former, while the rest are 

 almost uniformly distributed along the margin, so far as it is not 

 occupied by the central hooks and the two pairs of marginal hooks 

 mentioned first. The length of the central hooks is 24-31«, 



