The palps, both maxillary and labial, have two segments.
R, Line of origin of the posterior labial tentacle.
The labial tentacles and walls of the gut - very fine vessels with endothelial cell-lining are found.
1p, Labial palp.
The maxillary palps have usually three, the labial either two or four segments.
Maxillary and labial palpi are also present, and the latter, together with the labrum or lower lip, form the rostrum.
The beak is made up of horny elements, like the labial teeth, fused together; its edge, when sufficiently magnified, is seen to be denticulate, each denticle representing the cusp of a single tooth.
This is shown by the labial commissure and pedal cords of the nervous system, by the opening of the gonad into the right kidney, and by other points.
Head with two long labial palps; shell ovoid; operculum horny, semicircular, carinated.
Animals, 1877), they really belong to the labial segment which has not become completely fused with the headcapsule.
Interior of dorsal valve, showing muscular impressions and labial appendages.
In the Rhynchonellidae there are two short slender curved laminae, while in many genera and even families, such as the Productidae, Strophomenidae, Lingulidae, Discinidae, &c., there exists no calcified support for the labial appendages.
Interior of dorsal valve, to show the position of the labial appendages.
In the middle of words between vowels f was originally regularly voiced: life, lives; wife, wives, &c. The Latin V, however, was not a labio-dental spirant like the English v, but a bi-labial semivowel like the English w, as is clear from the testimony of Quintilian and of later grammarians.
The poison is secreted in modified upper labial glands, or in a pair of large glands which are the homologues of the parotid salivary glands of other animals.
- One, or a few, of the posterior maxillary teeth have a groove or furrow in front, which conducts the secretion of the enlarged upper labial glands.
- The teeth of Heloderma are recurved, with slightly swollen bases, loosely attached to the inner edge of the jaws; each tooth is grooved, and those of the lower jaw are in close vicinity of the series of labial glands which secrete a poison; the only instance among lizards.'
N, Anterior labial tentacle.
O, Posterior labial tentacle.
We thus expose the plough-like foot (I), the two left labial tentacles, and the two left gill-plates or left ctenidium.
I (5), one of the labial tentacles n is also thrown back to show the mouth w, and the two left gill-plates are reflected to show the gill-plates of the right side (rr, rq) projecting behind the foot, the inner or median plate of each side being united by concrescence to its fellow of the opposite side along a continuous line (aa).
The labial tentacles or palps of Anodonta (n, o in fig.
Their appearance and position suggest that they are in some way related morphologically to the gill-plates, the anterior labial tentacle being a continuation of the outer gill-plate, and the posterior a continuation of the inner gill-plate.
The gill-plates have a structure very different from that of the labial tentacles, and one which in Anodonta is singularly complicated as compared with the condition presented by these organs in some other Lamellibranchs, and with what must have been their original condition in the ancestors of the whole series of living Lamellibranchia.
I, Anterior labial tentacle.
K, Posterior labial tentacle.
Near the labial tentacles, but it is at first only a ridge, and does not project as a free cylindrical axis until the back part of the foot is reached.
1, Labial Tentacle.
L.a, Filamentous appendage of the labial tentacle.
Lb, Hood-like appendage of the labial tentacle.
- Diagram of a view from the left side of the animal of Anodonta cygnaea, from which the mantle-skirt, the labial tentacles and the gill-filaments have been entirely removed so as to show the relations of the axis of the gill-plumes or ctenidia g, h.
M, Line of origin of the anterior labial tentacle.
The labial tentacles are formed late.
- One row of branchial filaments is directed dorsally, the other ventrally; the mantle has a long posteroventral suture and a single posterior aperture; the labial palps of each side are fused together; shell elongate; hinge without teeth; periostracum thick.
- Labial palps free, very broad, and provided with a posterior appendage; branchial filaments transverse; shell has an angular dorsal border; mantle open along its whole border.
The labial palps are direct continuations of the lips.
Lucinidae.-Labial palps very small; gills without an external plate.
T, Labial tentacle.
Labial palps very large.
The labial commissure supplies only the buccal mass and the oesophagus and stomach.
La.c, Labial commissure.
There is thus a tendency to assimilation, and instead of a guttural followed by a labial semi-vowel, a new labial consonant p is produced.
According to Spengel, the pair of ganglia near the mouth, variously called labial or cerebral, represent the cerebral pair and pleural pair of a gastropod combined, and the parietosplanchnic pair correspond to the visceral ganglia, the commissure which connects them with the cerebro-pleural representing the visceral commissure.
La.c, Labial commissure.
It consists of ciliated epithelium, beneath which are two ganglia connected with the labial commissure by nerves.
They have two circlets of tentacles, a labial and a marginal, and there is only one ciliated groove in the stomodaeum, which appears to be the sulculus.
The upper ones are the largest, and are continuous anteriorly with the labial glands, the ducts of which open on the mucous membrane of the upper lip.
From the points where the cords meet the cerebral commissure, arise on each an anterior labial commissure and a stomatogastric commissure.
The labial commissure gives off a subradular commissure which also bears two ganglia, these being in close relation to a special sense-organ called the subradular organ, an epithelial projection with nerve-endings, lying in front of the radula and probably gustatory in function.