188 WHEELER. [Vou. IX. 
parasite is interesting as representing a condition intermediate 
between Gunda and the fresh-water Triclads, a condition in 
which the nervous system is quite as regular as that of Gunda, 
while the other organs are scarcely more regular than their 
homologues in the fresh-water species. 
The most striking peculiarity of the Triclad parasites of 
Limulus is the duplicity of the uterus and the independent 
openings on the surface of the body. v. Graff, who first observed 
this curious character (79), does not appear to have given 
it due weight. This character combined with another, vz., 
the complete absence of rhabdites, seems to me to be of suffi- 
cient magnitude to isolate these Triclads as a distinct family — 
Bdellouridae — coérdinate with the families Planariidze and 
Geoplanidz. Certainly the characters which distinguish this 
proposed new family from the remaining Triclads are as 
important as those used in the delimitation of many of the 
families of Polyclads. As a purely tentative arrangement of 
the group, subject, of course, to modification in the future, I 
would propose the following: 
Family Bdellouride. 
Ectoparasitic marine Triclads without auricular folds at the 
cephalic end; without pigment, except in the two eyes; without 
rhabdites ; with two uteri opening by discrete ostia laterad to the 
longitudinal nerves ; ejaculatory ducts opening separately very near 
the tip of the penis. Egg-capsules, elliptical or oblong, flattened, 
attached by a slender pedicel. 
* Large species, with typical Triclad gut; the posterior rami 
united by a fusion of two of the mesial diverticula only in old 
specimens (always?); anal end of the body widened into a 
glandular disc; anterior end narrow and tapering to a point 
when the animal is expanded; ducts at the anterior edges of 
the uteri; penis acuminate, with a broad base. BDELLOURA, 
Leidy. 
{ Testicular sacs small, about 60-100 in number on either 
side of the body, lying laterad to the gut diverticula ; brain 
relatively small, not contained in a fibrous capsule: Length 
