238 MR. J. D. MACDONALD ON THE ANATOMY AND 
coincidence or casualty. It would rather seem to indicate the fulfilment of some im- 
portant end in the propagation of the species. Mr. F. M. Rayner suggested to me that 
the phenomena of reproduction in the case of Tenia and Bothriocephalus afford a curious 
parallel to the circumstance just alluded to with reference to the Mdbalolo. The trans- 
verse fission in the latter case is evidently connected with the dispersion of the ova, rather 
than the development of new individuals from the pre-existing materials of the animal’s 
body, as in Nereis, &c. 
I had the good fortune to discover a single head of the Mbalolo,—and the only one to 
be found amongst a large bottleful of bodies and tails collected for me by my esteemed 
friend, the Rev. S. Waterhouse, Wesleyan Missionary, Fiji. The joints of the body, to the 
number of about twenty, remaining in connexion with the head, were considerably smaller 
than those that would succeed them were the specimen perfect ; besides which, the aciculi, 
of two sorts, were more numerous in the little bundles springing from the lateral tuber- 
cles. The dark spots and characteristic markings of the dorsal surface were also very 
faint, or scarcely distinguishable. The head itself was very little narrower than the joints 
of the neck, blunt and rounded, with a slight emargination in front. Eyes two, placed one 
on either side of the upper surface, including, in the space between them, three conical 
tentacula, of which the central is the longest, and projects a little beyond the head. 
The mouth was inferior, subterminal, and armed with two pairs of jaws—those of the first 
pair being sickle-shaped and simple, and those of the second broad and jaw-like, having 
a curved external outline and a series of dental points on their opposable border. The 
tissues in the neighbourhood of the jaws appear to be much indurated ; and one structure 
in particular is worthy of notice, that its true nature, if not already known, may be inves- - 
tigated in the neighbouring genera. It consists of two slightly diverging series of scale- 
like plates overlapping one another from before backwards, in which direction also they 
gradually increase in size. The free edges of the plates are directed backwards; and as 
distinct muscular bundles may be traced into their deep surface, it is highly probable 
that they are capable of elevation and depression, acting, so to speak, as a prehensile 
palate, opposable to the jaws. 
The typical elements of the lateral appendages of the body-segments (often so distinctly 
seen in allied Annelida) appear to have become blended together, more or less, so as to form 
a single setigerous tubercle, transmitting, however, as is usual, two characteristic kinds 
of setæ, and bearing a simple papilla-like, dorsal cirrus above, and a somewhat smaller 
ventral cirrus below,—the former lying near the outer extremity of the tubercle, and the 
latter somewhat hearer the base. The repetition of these cirri may be traced backwards, 
cae all = annuli, to the penultimate joint, in which they are quite suppressed ; but 
om reappear In the anal segment, and the ventral cirri in particular, having attained 
"1 considerable length, project posteriorly like those of better-known Nereids. Besides the 
En "i Puig sty lets of the feet (exhibiting so much sameness of character in all the Anne- 
E en, Bere ue = of M balolo, as above noticed, are of two distinct 
ilis Sith où tin dam ane el crate eo Me Like ee oompeomed ONE 
is much stouter and eng and terminating in an exquisitely fine point; while és 
r, with a small claw-like terminal appendage having two 
