ME. P. H. aOSSE ON THE DKECIOUS CHAEACTEE OF THE EOTIFEEA. 319 
the jaws, long before hatching. I was surprised at the great size of the newly-bom 
young, not only in proportion to the parent, but even to the egg from which it was just 
escaped. For, when I delineated it an hour afterwards (during which I did not perceive 
any manifest increase), its length, from the tip of the frontal antlers to the posterior 
tubercles, was -^th of an inch. The dimensions of the empty shell (fig. 15), which still 
retained its form, were X of i^oh : this continued attached to the parent 
for hours afterwards. This increase I suppose to be eflected by the expansion of the 
lorica (at first fiexible and membranous), which in the egg had lain in many folds, and 
by the imbibition of water into the cavity of the body. 
24. Soon afterwards I had a young male of the same species hatched. I selected a 
specimen with two small eggs attached, and isolated it in the live-box, examining it at 
intervals. At length I perceived the young male whirling rapidly about the box, and 
on looking at the adult, saw that one of the eggs was but an empty shell. By the aid 
of cotton filaments and the compressorium, I was enabled to keep it steady, and to examine 
and draw it with care (see figs. 18, 19). It is of the usual shape, with a well-marked 
neck, up to which a flexible lorica appears to reach. The head is broad, truncate, or sub- 
conical, with 'vibrating bristles set on the cone, and rotating bristly cilia around the 
margin. A head-mass, of irregular, rounded, or sacculated lobes, bears a lozenge-shaped 
red eye on its dorso-posterior angle (fig. 19). From each side of the head a chain of 
irregular masses runs do'wn to the posterior part of the body, probably answering to the 
tortuous glands of the female. A large mass, similar m appearance to the head, but 
distinct from it, occupies the middle of the body, extending down into the penis-foot. 
This great mass is continually moved by quick contractions up and down, but it does 
not appear to be tubular and hollow. The common white, opake, granular masses are 
enveloped in it, near the hind part of the body. 
25. From this time I made no fui'ther investigation into the subject until the autumn 
of the present year (1855), when I had an opportunity of examining the beautiful and 
interesting marine species B. Mulleri, and of seeing, with satisfaction, that in the point 
of its ceconomy, which is the subject of this memoir, it differs not from its congeners of 
fresh water. The males, however, displayed an internal organization more developed than 
in any species that I had yet seen, -with the exception of the Asi[)lanchn(B. 
26. In July last, my kind friend Mr. Brightwell of Norwich sent me a small phial 
of sea-water much filled with this species. I immediately di’vdded the contents among 
my Aquaria, where they increased rapidly. Many of the females have two or three 
male eggs attached, which are Y^th of an inch in length, and others carry one or two 
female eggs a^th of an inch long. The male young (fig. 20) is of iiich long, 
exclusive of the foot, and about -g-^^h of an inch wide, "with a distinct, but very flexible 
lorica, of which the anterior edges seem to become membranous. There is a great 
conical head (fig. 20 a), set with large setiform cilia all over the front, and behind 
descending into a rounded mass of several lobes, with a red eye (b) on the truncate apex 
of the posterior lobe. Several muscle-threads (c) pass longitudinally from this head- 
