100 On Euchlanis triquetra and E. dilatata. 
edges of which, when the animal is held by the compressorium, 
give rise to two sharp lines, which appear to he the hounding lines 
of the under surface of the lorica, and exactly give the impression 
of there being a naked gap at (&), leaving the body unprotected. 
This is better seen in Fig. 4. 
To return to Euchlanis triquetra. Of its internal organs, its 
enormous brain (Z) claims the first notice. Anyone unacquainted 
with the subject may well smile at the idea of crediting such an 
atom with such a brain; but the reasons which lead those who 
study the rotifers to say that the organ is a nervous centre are, I 
think, convincing. To lessen the marvel I may mention that the 
contents of the brain sac (Z) seem to be of a very fluid and trans- 
parent nature, with the exception of the hinder portion ( m ), which 
appears to be nucleated and more dense. 
Immediately under the brain is the red eye-speck ( n ) and the 
mastax (d), while above it and close to it is the tactile organ (Ji) ; 
this arrangement is pretty general among the rotifers. 
The passage through the mastax leads by a short tube to the 
stomach (o), which is generally dotted over with oil-globules, and 
often in quicunx fashion. 
Two muscles (p,p) cross the surface of the stomach, imbedded 
in its surface, and constantly twitching it from side to side. The 
stomach is usually subdivided into an upper and lower portion, as 
in the figure ; the lower portion being densely ciliated. But this 
subdivision is not permanent in the same individual. 
There are the usual convoluted tubes (q) on either side of the 
body, bearing on an average four or five vibratile tags on each 
side ; and at (r) is the contractile vesicle, into which the tubes open, 
and from which a discharge is kept up every ten or twelve seconds 
into the vent. 
The ovary (s), containing the embryos (t, t ) and the full- 
developed egg (u), opens also into the same place. 
I have only to add that the pincers (v, v ) exude, apparently, 
a viscid substance, like that of a spider’s web, by means of which 
the animal adheres to any substance it pleases. I have never seen 
them pinch anything, but I have seen them adhere by their extreme 
tips to the glass ; and I think I have on more than one occasion 
seen traces of this viscid secretion on the glass itself : the power of 
secreting such a fluid is, I believe, common to the majority of the 
rotifers. 
The figure of Euclilanis dilatata (Fig. 5) is so hke that of 
E. triquetra, that it requires no further explanation. 
