438 
NOTES ON LOPHOPUS CRY ST ALLINU S . 
By J. JOSSELYN RANSON and T. GRAHAM PONTON. 
T HE subject of the following notes is one of the most 
beautiful of the fluviatile representatives of the Polyzoa, 
that remarkable group of animals which stands at the bottom 
of the Molluscan series. The Lophopus may be frequently 
found in sluggish streams scattered along the stems of various 
water-plants, such as Lemna, Sparganium, and others. It is 
usually attached in the axils of the leaves, and, when taken 
out of the water, presents a jelly-like appearance, and might 
then easily be mistaken for ova of one of the water snails. 
On putting one of these jelly-like masses into a tube filled 
with clear water, however, and after the lapse of a few minutes, 
examining it with a lens, its true nature will at once be 
revealed. Delicate tubes will be slowly exserted from the 
mass, each tube to be crowned with a beautiful fringe of nearly 
transparent tentacles. These are in a double row arranged in 
a crescentic or horse shoe -shaped series, this peculiar arrange- 
ment being, with the exception of Fredericella, the tentacles 
of which are disposed in a circular order, a characteristic of 
the fresh-water Polyzoa. 
The Lophopus is particularly interesting as being the first 
discovered of the class, having been noticed by Trembley as 
early as the year 1741. 
It was long confounded with two other genera, Yluma- 
tella and Alcyonella ; Dumortier, however, who re-discovered 
it in 1834, recognized it as the type of a new genus. 
The generic characters, as given by Dr. Allman in his 
elaborate monograph of the fresh-water Polyzoa, are as 
follows : — 
Ccencecium, sacciform, hyaline, with a disc which serves for attachment 
but not for locomotion ; ectocyst gelatinoid ; orifices scattered, statoblasts 
elliptical, with an annulus, but without marginal spines. 
There is only one species, Lophopus Crystallinus (Pallas), consequently 
the specific characters are the same as that of the genus. 
The above description is similar to that given by Baker 
and Yan Beneden, except so far as that they consider the 
disc to be used in locomotion — an opinion which our own 
observations confirm ; for, having kept many specimens for a 
lengthened period, and having many opportunities of carefully 
examining them, we have come to the conclusion that the disc 
