12 Prof. KótnikER on the Structure of 
penetrates through the muscular envelope of the body into the abdominal 
cavity. These organs are probably an apparatus for conveying water into 
the abdominal cavity, resembling that of the Radiata and Mollusca. 
b. Muscular. System. 
This system is highly developed ; the suckers and the penis are both fur- 
nished with muscles, and there is also a peculiar muscular envelope of the 
body. The latter has a very curious organization: it consists of three lay- 
ers, the external of which is 0:048 P. L., and the innermost 0:024 P. L. in 
thickness; both are formed by circular fibres, the former being continuous 
with the corium, and the latter containing a tubular cavity, through which 
the intestine passes. The middle layer is formed of longitudinal fibres, which 
are arranged in such a manner as to form numerous septa or partitions, radi- 
ating from the centre to the cireumference, i. e. from the central to the external 
layer, thus presenting very much the appearance of a carriage-wheel. There 
are, moreover, other very short transverse fibres uniting these septa. Con- 
sequently the entire envelope of the body consists of four distinct species of 
fibres, very singularly disposed. | 
The muscles of the acetabula are the following. Each one is attached to 
the muscular envelope by two large retractors; and it has besides a small 
layer of circular fibres surrounding it externally, and a thick stratum of lon- 
gitudinal ones internally. ; 
The penis has a slight layer of transverse as well as longitudinal fibres. 
The muscles seen with the microscope are, like those of the human intestine, 
composed of large flat fibres with nuclei, and neither showing transverse lines, 
nor being united in bundles, 
C. Intestine. 
As far as I could trace the intestine by dissection and with the microscope, 
mouth is placed at the anterior extremity 
and is small and elliptic, without any lips or 
Which nearly fills the cavity 
r not I cannot tell, because, 
I was not able to find an anal orifice. 
