436 MR. P. H. GOSSE ON THE STRUCTURE, FUNCTIONS, AND HOMOLOGIES 
nearly in the longitudinal plane of the venter ; so that the aperture of the mastax is 
brought to the surface, without the intervention of any appreciable funnel. 
82. Scarcely differing from this structure is that of the curious little Alhertia ver- 
miculus, first found by M. Dujardin, living entozoically in Lumhricus and Limax, 
and which I have found in the intestine of Nais prohoscidea (figs. 52, 53). Whether 
the uncus has an accessory tooth, or not, I cannot certainly say, owing to the minute- 
ness of the parts ; the animal being only of an inch in length, and the dental 
apparatus being unusually minute in proportion. It is, however, frequently protruded, 
to the extent of fully half of the apparatus, from the front, and vigorously snapped. 
83. Furcularia marina (figs. 54, 55) is another species, in which these organs are 
greatly protrusile ; the whole of the long mallei being sometimes exterior to the 
frontal disk (fig. 54). The incus (fig. 55) seems to me a simple, much-arcuated for- 
ceps ; and the mallei to be without unci, the manuhria (simple incurved rods) being 
articulated to the bases of the rami. M, Dujardin describes and figures them differ- 
ently*, but I believe he is mistaken. 
84. We are now prepared to understand the form of dental apparatus, which has 
hitherto appeared perfectly anomalous in this class, — that of Asplanchna, as described 
and figured by Mr. Brightwell and Mr. Dalrymple, in the case of A. Brightwellii, 
and by myself in that of A. priodonta. To these must be added Notommata myrmeleo, 
and N. syrinx, of Ehrenberg ; referrible doubtless to the same genus. A moment’s 
comparison of the jaws of A. priodonta (Plate XVIII. figs. 56 to 59) with those of Syn- 
chceta tremula, or of Diglena forcipata (Plate XVII. figs. 41, 50) either opened or 
closed, will show that the former constitute an incus, with the fulcrum much dimi- 
nished ; the very row of teeth that runs, like the edge of a saw, along the interior of 
the ramus (figs. 58, 59), having its counterpart in the ridges and setee ai Diglena as 
also in the teeth of these organs in Notommata aurita. 
85. The mallei, at first sight, seem wholly wanting in Asplanchna-, but they are 
really present, though in a state of extreme attenuation and degeneration. Mr. Dal- 
rymple thought he saw an occasional glimpse of an accessory curved point, outside 
the tip of each jaw, in A. BrightwelUi ; and I have invariably observed the same in 
both that species and A. priodonta (figs. 58, 59). It is a curved pointed rod, which, 
at its lower end, that ordinarily would be free, is attached to a process, which is 
itself attached, I believe, by a transverse ligament, to the ramw.?, near its articulation. 
It is most evanescent ; yet it is not dissolved by treatment with potash, and I have 
no doubt that it represents the malleus. 
86. HhQ fulcrum, though short and thin, is very deep ; the depth in fact exceeding 
the length (fig. 59) ; and it affords a clear insight into the nature of the articulation 
of the 7'ami — a ginglymus of the simplest kind ; the articulating parts having straight 
parallel edges, united by an interposed membrane. 
87. Another peculiarity in this genus is the absence of the mastax-, at least in its 
* Infus. p. 649 ; and pi. 22. figs. 4, c, n, e. 
