456 Wisconsin Academy of Sciences, Arts, and Letters. 
which disappear when the body is fully extended in swimming. 
There is no true foot and the tail is a small fold above the toes; 
between the toes is a minute, but quite distinct, rounded papilla. 
The toes are short, slightly decurved and emarginate on their 
inner edges, which gives them the appearance of being clawed; 
their length is about one twentieth of the length of the body. 
The dorsal antenna is a minute setigerous papilla in the normal 
position; the lateral antennse have not been observed. 
The corona extends down on the ventral side somewhat more 
than one fourth of the length of the body. The auricles are small 
and rounded; a fairly prominent rostrum is present and curves 
down over the corona. The mouth is a little below the center. 
The mastax is virgate with strongly asymmetric trophi of a 
simple type. The fulcrum is very long and slender, tapering 
gradually towards the posterior end, which is expanded into an 
oval plate for the attachment of the muscles of the piston. The 
rami are roughly triangular in ventral view; the dorsal branch 
forms an acute angle with the ventral portion. The alula of the 
left ramus is nearly as long as the ventral part of the ramus itself 
and forms a very acute angle with the fulcrum. The right alula 
is smaller and somewhat more divergent; it is excavate dorsally 
and the sinus is reenforced by a strong rib, easily seen in the ven¬ 
tral view. The unci have a strong ventral tooth, followed by a 
much smaller second tooth. The manubria are rodlike and formed 
entirely by the median cell, only a slight ventral hump indicating 
the normal posterior limit of the ventral cell. The right manu¬ 
brium is only two thirds as long as the left, and both are slightly 
expanded at the posterior end. The piston is very large and fills 
the entire cavity of the mastax. Two salivary glands are present; 
the left gland is very large and curves under the mastax, while 
the right gland is rudimentary and apparently not functional. 
The oesophagus is long and slender. The gastric glands are 
very small and rounded. There is no distinct separation between 
stomach and intestine. The bladder is formed by an expansion of 
the cloaca. The foot glands are large and slightly club-shaped. 
The ovary is normal. 
The ganglion is large and elongate saccate. The retrocerebral 
organ consists of a small, pyriform sac, usually opaque with bac- 
teroids; no subcerebral glands are present. The eyespot is a 
granular mass of red pigment at the posterior end of the ganglion. 
Total length 150-200/>t toes 8-10/x trophi 28/u,. 
