6 
Transactions of the Society . 
am indebted to my friend, Mr. F. E. Dixon-Nuttall, and also by 
the mounted slide under the Microscope in the room, the shape of the 
male of Bhinops vitrea differs somewhat from that of the female ; the 
body becomes suddenly narrower in the lumbar region, whilst in the 
female it tapers very gradually down to the toes. The body is very 
lithe and soft, bending constantly in every direction. The corona with 
its proboscis-like dorsal projection resembles that of the female in 
every way, and two red eyes are in the same manner situated near the 
extremity of the proboscis, each having a minute spherical crystalline 
lens imbedded in the red pigment. A dorsal antenna is seen on the 
dorsal side, a little below the eyes (this antenna is also present in the 
female), and the two lateral antennae are very conspicuous at the 
projecting angle of the lumbar region, each furnished with a brush of 
abnormally long setae ; in the female the lateral antennae are very 
small. The foot is short, consisting apparently of one joint containing 
the two foot-glands, and terminating in two minute toes. 
The chief characteristic and the most abnormal feature about this 
male is the possession of functional jaws and intestine. The jaws are 
like those of the female in structure, but in one specimen I thought 
the right malleus shorter than its companion on the left side. The 
oesophagus is a thin, narrow tube leading to an elongated thick-walled 
stomach, with two gastric glands attached, and continued behind into a 
narrow intestine, all ciliated in the interior. The jaws were frequently 
moving, but the contents of stomach and intestine were very slight 
and of a greenish tinge, without solid particles of large size. It seems 
clear, however, that the male of Bhinops can take in some food, and 
therefore sustain life and live longer than all other known male 
rotifers. No trace of an ovary could be found, but in its place, 
ventral to the intestine, is a rounded sperm-sac, at the lower end of 
which the spermatozoa could be plainly seen in motion, terminating 
in a duct with the usual retractile and ciliated copulatory organ. A 
small contractile vesicle and lateral canals with flame-cells attached 
are present as usual. 
In swimming the movements of these males were very lively, 
turning, bending, and twisting continually, and contrasting markedly 
with the slower gliding motion of the females. 
In size the males are 1/135-1/120 in. (0*188-0 *212 mm.), or 
a little over half the size of the females, and much more slender, on 
account of the narrower posterior part of the body. 
The discovery of this male opens up interesting questions as to 
the evolution of the male rotifers, which in the great majority of cases 
are little more than perambulating bags of spermatozoa, living a very 
short and merry life. The most rudimentary male I have yet seen is 
that of Polyarthra platyptera, which can hardly be distinguished 
from a Vorticella which has become detached from its stalk. It 
seems evident, however, that the males are simply degenerated forms, 
though why degeneration should have occurred at all must still remain 
