1905 | i THE HaIrR-EEL. ; 135 
studded with small rounded papilla. Beneath the outer cuticle is 
an inner cuticular layer, underneath which is a thinner stratum 
composed of a granular matrix containing a few nuclei. This 
stratum sends up through the next layer, to be described later, 
a thin perpendicular lamella, which expands into a thickened rod 
or cylinder lving longitudinally upon the muscle layer. It may be 
likened to the hypoderm ridges projecting inwards from the 
subcutaneous ijayer in the Nematode Ascaris. Ascaris possesses 
four such internal ridges, dorsal, ventral and two lateral, these 
last being pierced by a minute canal, probably excretory in nature. 
If this comparison be justified, the ventral ridge (Grenacher’s 
‘‘Bauchstrang”’*) is the sole representative of the hypoderm ridges 
in Ascaris. A thick muscular layer lies internal to the cuticular 
and granular layers mentioned. Its greatest thickness is midway 
along the body, and it is of a most interesting character. The 
fibres are flattened and longitudinal: but in transverse ver- 
tical section the cut ends look like radial fibres converging 
upon the internal organs. They are really large muscle cells, 
naked and pressed against each other, and are the simplest form 
of muscular tissue known, if we except the neuro-muscle cells in 
the Coelenterates, or the pecular transition cells in Ascaris. Each 
fibre exhibits a slight cavity which is much reduced, owing to 
their mutual pressure and flattened form. To this thick layer of 
muscle cells Gordius owes its marvellous power of contortion, of 
tying itself up in complex knots, and ceaselessly untying them. 
Inside the muscle layer is the perienteric tissue, composed of 
irregular nucleated cells and fibrous intercellular tissue. In the 
midst of this tissue the central digestive tube passes, and on 
each side of the tube the genital glands lie. The latter, as 
long ovaries and cylindrical testes, pass backward and finally 
unite with a large terminal chamber, above which lies, in the 
female Gordius, the receptaculum seminis. When the ova are 
nearly mature, the ovaries become greatly expanded, and 
along the inner margin of each of these organs, passes an efferent 
canal, called the egg sac in the female, which further back be- 
comes a slightly convoluted oviduct, or vas deferens, according to 
