In many bloodsucking flies, for example, the galea is absent, while the lacinia becomes a strong knife-like piercer and the palp is well developed.
2, III), while the palp is wanting.
In butterflies and moths the lacinia is absent while the galea becomes a flexible process, grooved on its inner face, so as to make with its fellow a hollow sucking-trunk, and the palp is usually very small.
B, Section through compound eye (after Miall and Denny); C, organs of smell in cockchafer; (after Kraepelin); D, a, b, sensory pits on cercopods of golden-eye fly; c, sensory pit on palp of stone-fly (after Packard); E, sensory hair (after Miall and Denny); F, ear of long-horned grasshopper; a, Front shin showing outer opening and air-tube; b, section (after Graber); G, ear of locust from within (after Graber).
Mandibles present in pupa, vestigial in imago; maxillae suctorial without specialization; first maxillae with lacinia, galea and palp. Prothorax small.
E, First maxilla; a, cardo; b, stipes; c, galea; d, lacinia; e, palp. B, Second maxillae (Labium); a, mentum; b, ligula (between the two galeae); c, c, palps.
A, mandible; b, c, palp and lacinia of first maxilla; d, e, g, h, mentum, palp, fused laciniae (ligula or "tongue") and galea of 2nd maxillae.
The mandibles are without palp. The pairs of feet are four to six.
The mandibles are normally five-jointed, with remnants of an outer branch on the second joint, the biting edge varying from strong development to evanescence, the terminal joints or " palp " giving the organ a leg-like appearance and function, which disappears in suctorial genera such as Paracytherois.
F, Its palp. Highly magnified.
In the Limnephilidae the maxillary palp is three-segmented in the male, the larvae are variable in habit, many forming cases of snail-shells.
Mxp, Maxillary palp. 1, Ligula or "tongue."
This form is retained, with little alteration in some adult Copepoda, where the biramous " palp " still aids in locomotion.
In most cases, however, the palp loses its exopodite and it often disappears altogether, while the coxal segment forms the body of the mandible, with a masticatory edge variously armed with teeth and spines.
In a few Ostracoda, by a rare exception, the masticatory process is reduced or suppressed, and the palp alone remains, forming a pediform appendage used in locomotion as well as in the prehension of food.
The endopodite, when present, is unsegmented or composed of few segments and forms the " palp," and outwardlydirected lobes representing the exopodite and epipodites may also be present.
The Ostracoda might have been derived from the same stock were it not that they retain the mandibular palp which all the Phyllopods have lost.
To) becomes in Crustacea the " walking leg " of the mid-region of the body; it becomes the palp or jointed process of anterior segments.
A second ramus, the " exopodite," often is also retained in the form of a palp or feeler.
The range of modification of which the rami or limb-branches of the limbs of Arthropoda are capable is very large, and in allied orders or even families or genera we often find d z what is certainly the palp of the same appendage (as determined by numerical position of the segments) - in one case antenniform, in another chelate, in another pediform, and in another reduced to a mere stump or absent altogether.
Milne-Edwards, who was followed by Huxley, long ago formulated the conclusion that the eye-stalks of Crustacea are modified appendages, basing his argument on a specimen of Palinurus (figured in Bateson's book (1), in which the eye-stalk of one side is replaced by an antenniform palp. Hofer (6) in 1894 described a similar case in Astacus.
This may be filiform or brush-like or lamellate when it is an antenna or palp; a simple spike (walking leg of Crustacea, of other aquatic forms, and of Chilopods and Diplopods); the terminal joint flattened (swimming leg of Crustacea and Gigantostraca); the terminal joint provided with two or with three recurved claws (walking leg of many terrestrial forms - e.g.
The endopodite may be retained as a small segmented palp at the side of the gnathobase or disappear (mandible of Crustacea, Chilopoda and Hexapods).
As many as six pairs of appendages following the mouth may have an enlarged gnathobase actually functional as a jaw or hemignath, but a ramus is well developed on each of these appendages either as a simple walking leg, a palp or a chela.
The mandibular parapodia may be supposed during the successive stages of this history to have had, from the first, well-developed rami (one or two) of a palp-like form, so that the change required when the mouth passed away from them would merely consist in the suppression of the gnathobase.