THE CKOWN ANIMALCULE. 
31 
than Ehrenberg has figured them. I have traced them to a 
length equal to two -thirds of the greatest diameter of the body.* 
The points, however, run out to an extreme tenuity, and can 
only Jie perceived by the aid of delicate manipulation of the 
microscope. The five arms rise erect from the front, and con- 
verge to a rounded point after bulging outward, so as to present 
the figure of a tall crown or mitre (whence the generic name) ; 
but the points do not actually meet. It is rare to see a speci- 
men with the arms spread, as Pritchard has figured (after 
Ehrenberg) ; I have once seen it in this condition ; but I am 
persuaded that it is a mark of weakness or disease. 
The front, at the base of the arms, forms a broad head, 
which is separated by a sort of neck from the body. This 
neck consists of two thickened collars, produced by deep 
annular infoldings of the skin. The body is irregularly cylin- 
drical, or nearly so; but is generally swollen out in various 
parts by the full viscera, and the developing eggs. The dorsal 
side is the more swelling, and shows more distinctly the some- 
what abrupt attenuation into the long and slender foot.f At 
its junction with the body, the foot is twice or thrice the 
diameter to which it diminishes at its lower extremity, where 
it is permanently attached to some foreign object, such as the 
leaf or stem of some submerged water-plant. Throughout its 
length this organ is much and irregularly wrinkled; it is 
capable of some degree of contraction, but it cannot be 
retracted within the body ; it never shows any trace of 
those telescopic false joints which are so conspicuous in the 
Pliilodinadce. 
The Case. — The body is encased in a gelatinous envelope 
(pi. iii.), the general form of which is sub -cylindrical ; but 
the outline is thrown, into irregular transverse folds, appa- 
rently through sinking from its own weight. It is not a thin 
tube, as represented by Ehrenberg, with a roomy cavity, within 
which the animal lives, as Mclicerta does; but is manifestly a 
thick and solid (if such a term is not a misnomer as applied to 
such a material) mass of gelatinous substance, with the excep- 
tion of the space actually occupied by the body of the annual. 
From observations made upon the enveloping case, on occasions 
in which, for some reason or other, the animal voluntarily for- 
sook it, it was apparent to me, that there was no organic con- 
nexion between the animal and its case, after the latter was 
once formed. The cavity left was nearly of the same form and 
dimensions as the body and foot, showing that it had been 
* Leydig makes them equal to the full diameter of the body. 
t Leydig’s figure (in Sieb. and Koll. Zeitschr., July, 1854) is, both in outline 
and in anatomical details, too diagram-like for life. 
