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SUMMARY OF CURRENT RESEARCHES RELATING TO 
externally a sub-symmetrical appearance, but in its structure it is char- 
acterised by what may be described as atrophy of the left half of the body. 
The left intestinal diverticula are aborted. The mouth is placed at the 
middle of the length of the body, but approximated to the left margin. 
The cerebral ganglion is also approximated to the left margin. Through- 
out the body, and especially prominent in the anterior and posterior 
regions, is a close reticulum of fine anastomosing tubules, probably 
genital. 
The discoverer would place this remarkable form in the order Arclii- 
planoidea which he suggested for the reception of Coeloplana and Cteno- 
plana. 
The locomotion is usually conducted in a somewhat one-sided fashion, 
and the number of marginal eyes on the forward directed right lobe of 
the head is more than twice as many (56 : 24) as on the left lobe. 
Three new Polyclads.* — Dr. Marianne Plehn describes three new 
forms. The first —Polyporus csecus g. et sp. n., from Spitzbergen, is one 
of the Leptoplanidse with a very tough broadly oval body, with the 
mouth about the middle of the ventral side, with pores from the in- 
testinal branches on the margin all round, with separate genital aper- 
tures, with a second marginal opening to the female apparatus, and with 
no eyes. The second — Leptoplana californica — resembles the Lepto- 
plana in most respects, but has a single genital aperture. The third, 
also from Monterey Bay, California, is named Amblycerseus luteus g. et 
sp. n. It is one of the Euryleptidie, a large delicate form, with very 
high dorsal ridge, with the mouth in the anterior part of the pha- 
ryngeal pouch, but at some distance from the brain, with a pharynx 
tending to be collar-like, with numerous narrow intestinal diverticula, 
with small solid tentacles, and with eyes on the tentacles and anterior 
margin. 
Incertse Sedis. 
Ptychodera.f — Dr. A. Willey found a Ptychodera, which may be 
probably identified with P. flava Eschscholtz, in great abundance near 
the low-tide mark on the small islet of Amedee, eight or ten miles inside 
of the great Barrier Beef of New Caledonia. “It occurred near the 
surface of the sand, chiefly underneath loose stones, often adhering to 
the latter, and creeping into the holes with which the coralline blocks 
are riddled.” On the Isle of Pines it was equally abundant, often in- 
volved in the roots of the tussocks of seaweed. The individuals averaged 
in length from 1 J to 2 or even 3 inches ; but, after the captive specimens 
got rid of the sand in their intestine, they sometimes stretched out to 
over 5 inches. The details as to the life of the animal are important ; 
for this is the first time that an Enteropneust with a free pharynx has 
been studied alive. 
Among the author’s principal results are the following : — The pre- 
sence of the genital pleura, of external liver saccules, and the length 
of the collar region, show that Ptychodera flava should be assigned, as 
has been done by Spengel, to the amended genus Ptychodera ; and that 
it belongs to Spengel’s sub-genus Chlamydothorax , is shown by the 
* Jenaische Zeitschr. Naturwiss., xxxi. (1897) pp. 90-9 (1 pi.), 
t Quart. Journ. Micr. Sci., xl. (1897) pp. 165-83 (1 pi.) not in this part. 
