On Euclilanis triquetra and E. dilatata. 
99 
What a severe trial it will prove to both will be readily seen 
when it is understood that Euchlanis is incessantly in motion, now 
rolling over as it swims, now catching hold with its pincers, and 
jerking itself backwards and forwards; and that the instant it is 
held with the compressorium it begins to thrust its head in and out 
of its lorica, and continues to do so, without intermission, till it is 
released. 
It is useless, of course, to use high powers on a rapidly-moving 
object, and yet with powers less than k inch very little can be 
made out. The most successful method of attacking the puzzle is 
the employing of the dark-field illumination, especially that with 
Wenham’s paraboloid. 
It will be seen from Fig. 1 that if I have rightly interpreted 
the disk, the cilia on Euclilanis triquetra are divided into several 
groups, two at the sides, like whiskers ( b , b), two parallel rows 
(c, c) running down to the mastax (d), and performing the office 
of conducting to the mouth and jaws the food brought by the 
coarser cilia. 
There is another row (e) along the forehead, while from the 
disk itself spring up four papillae (/, /), (g, g), the former of which 
have curved motionless setae on them, while the latter ( g, g) are 
evidently perforated tubes, and probably contain some tactile organ, 
which, however, I have never seen protruded. There is an obvious 
tactile organ (h) on the medial dorsal line and just above the disk. 
Before I describe the internal organs I will take the lorica, 
which Ehrenberg affirms to be slit underneath longitudinally right 
down the middle of the ventral surface. Here I am quite positive 
that the great naturalist is in error ; the peculiarity he describes 
does not exist, while he omits one quite as striking. 
If Euclilanis triquetra be carefully watched with the dark-field 
illumination, the flashing of the light from its extremely transpa- 
rent but highly reflecting lorica will reveal its true form. It will 
be best understood from Fig. 2, which is a cross-section of it 
through the middle of the back, viz. at the point (k) in Fig. 1. 
The lorica is something like a glass dish-cover, rising into a 
very high ridge, and placed on a dish which it overlaps. 
Fig. 2 shows the upper portion or cover (a) and the lower flat 
plate or dish ( b ), with a connecting incurved rim (c) lying between ; 
though whether this portion be chitinous, like the lorica itself, or 
only a soft membrane, I have been unable to discover. That there 
is a connection may be easily shown by drying the animal on a slip 
of glass, when on again dropping water on it, the connecting por- 
tion may be seen to bulge out. 
Fig. 3 is a similar cross-section of Euclilanis dilatata; which 
animal also, in my opinion, has no medial division of the under 
portion of the lorica : it has, however, a raised portion (a, a), the 
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