456 OBSERVATIONS ON A NEW TAILLESS CERCARIA, 
is perceived a similunar body, transversely placed like a 
gland, formed with a membrane and some cells contained in 
it. This semilunar body has a total breadth of 0*216 mm., 
a length (starting from the tangent of the anterior point of 
the superior curvature to the tangent of the posterior edge 
of the swellings) of 0T44. The internal swelling has the 
transversal diameter of 0T08, the internal one of 0*080. 
On both sides, laterally to the ventral sucker, issues an 
apparently globular tube, that extends in forming a curve 
with its convexity outwards, in the ventral part of the animal. 
The left ventral lateral tube is long, 0*820 mm. ; it presents 
nearly at the beginning a swelling measuring 0*168; after 
the swelling it gets a diameter of 0*096, and ends in an 
obtuse point. The right ventral lateral tube is long, 1*200; 
it is destitute of a prominent swelling, and has a maximal 
bigness of 0*120. These tubes consist of elements analo¬ 
gous to those of the above-mentioned semilunar body; they 
have, however, a darker-yellowish colour, and likely repre¬ 
sent the beginning of the two branches of the digesting 
tube. 
In the anterior ventral region, behind the sucker and 
somewhat on the left, are visible two spheroidal bodies, 
formed by a capsule and some cellular contents. The cap¬ 
sule is of a connective nature, studded with a great many 
little round nuclei, brightly reflecting the light, and of the 
diameter of 1—2 ft. The contents are formed by round 
cells with a finely-granular protoplasma, with a nucleus and 
some nucleola. 
These two spheroidal bodies very probably represent the 
testicles. Of these, that which lies below and more on the 
left, is the larger, and has a transversal diameter of 0*208 mm., 
the longitudinal of 0*192; the right one, on the contrary, 
placed almost in the middle line, measures transversely 
0*192, longitudinally 0*160. 
Now, it is very difficult to detect what species of distoma 
this Cercaria belongs to, and I never met with any others 
to try experiments for the purpose. Should, perhaps, this 
larva have fully developed itself in some animal species 
feeding on frogs ? It is highly probable. 
Note by Dr. Cobbold. —This little trematode, of which 
Professor Perroncito has already given some account in the 
Annali della 11. Accad. d*Agricolt, di Torino , forcibly 
reminds one of the Distoma lateum of the common water-snail 
(Paludina vimpara) ; and, but for the circumstances that 
l)r. Pagenstecher failed to rear sexually mature flukes in 
frogs fed with the pupal flukes from the snails, I should have 
