OF THE MANDUCATORY ORGANS IN THE CLASS ROTIFERA. 
433 
trale {fulcrum) droite, tres-longue, elargie a sa base This description is so vague, 
that it might embrace a multitude of widely remote species and genera ; while it does 
not at all indicate the true peculiarity of the organs it professes to define. 
65. Furcularia gihba (figs. 35 to 37) comes, in the form of its jaws, very near to 
Not. lacinulatu', but most of the species of this genus, as described by Professor 
Ehrenberg {not by M. Dujardin, who includes in it a number of dissimilar species, 
already well defined and separated by his Prussian predecessor), are distinguished 
by the manubria being dilated laterally at their free extremity, so as to resemble 
the foot of a towel-horse. These expansions are doubtless for the attachment of 
muscles (which, however, I have not been able to define); and as the simple uncus 
is affixed to the edge of the ramus only by its point (fig. 36), a greater play is pro- 
bably afforded it by such muscles, in the combined action of the jaws upon the prey. 
66. The rami are broad, glassy, vaulted, cleft throughout, capable of widely open- 
ing (fig. 36), and produced into long decurved points (fig. 37). Their lower edges 
are thickened, so as to form a marginal band. 
67. Furcularia marina has its manducatory organs formed on another type, ap- 
proaching that of Diglena ; as I shall presently notice. 
68. Notommata gibba (figs. 38 to 40) prepares us for the remarkable modification 
of these organs which we find in Synchceta and Polyartkra. It is a minute species, 
having much of the appearance and habits of Not. lacinulata ; but remarkable for the 
length and lozenge-form outline of the mastax, owing to the great posterior develop- 
ment of the ventral lobe, which is itself dependent on the great elongation of the 
fulcrum. The manubria (fig. 39) are long and incurved at their free extremities ; the 
unci are single-toothed, and soldered to the rami. The latter are curved, glassy 
blades ; along the middle of each runs a line, which is difficult to understand : after 
much study, I think it to be the angle of depression of the surface, as represented 
ideally at fig. 40. 
69. In Synchceta and Polyarthra, the mastax and its included organs attain their 
maximum of development as regards dimensions, though not as regards complexity. 
In some species of the former genus fully one-third of the entire bulk is occupied by 
these organs. Owing, however, to the extreme delicacy of the parts, particularly of 
the mallei, and the unequal refraction produced by the prismatic form of the animals, 
the structure is unusually difficult to resolve. Ehrenberg evidently did not under- 
stand it : the points of the unci he appears to have seen, in S. pectinata, but no more ; 
and the frontal styles he mistook for accessory jaws -f-. In Polyarthra, he merely 
says that “there are two single-toothed jaws:{:.” His figures give little or no light 
on the true structure in either genus. 
70. Dujardin knows nothing of Synchceta, no species of which he seems to have 
seen ; but concludes, most groundlessly, that it is not distinct from Hydatina. Of 
Polyarthra he merely says, “Machoires unident^es^ and though he figures a spe- 
* Infusoires, p. 651. f Infusionsthier. p. 437. 1 Ibid. p. 440. § Infus. p. 641. 
