In some freshwater Copepoda the secretion of the dermal glands forms a gelatinous envelope, by means of which the animals are able to survive desiccation.
The most important of these belong to the category of dermal glands, and may be scattered over the surface of the body and limbs, or grouped at certain points for the discharge of special functions.
BIRD - Louse, any small flat degenerate wingless neuropterous insect of the group Mallophaga, parasitic upon birds and mammals and feeding upon dermal excretions or upon the softer parts of hair and feathers.
The scutes or dermal portions of the scales are more or less ossified, especially on the back, and form the characteristic dermal armour.
These horns, which are of a more or less conical form and usually recurved, and often grow to a great length (three or even four feet), are composed of a solid mass of hardened epidermic cells growing from a cluster of long dermal papillae.
Protonemertini, in which there are two layers of dermal muscles, external circular and internal longitudinal; the nervous system lies external to the circular muscles; the mouth lies behind the level of the brain; the proboscis has no stylet; there is no caecum to the intestine.
About 700 species of Carboniferous fish have been described largely from teeth, spines and dermal ossicles.
Mesonemertini, in which the nervous system has passed into the dermal muscles and lies amongst them; other characters as in Protonemertini.
Heteronemertini, in which the dermal musculature is in three layers, an external longitudinal, a middle circular, an internal longitudinal; the nervous system lies between the first and second of these layers; the outer layer of longitudinal muscles is a new development; there is no intestinal caecum; no stylets on the proboscis and the mouth is behind the level of the brain.
Owen to the typical representative of a group of gigantic, armadillo-like, South American, extinct Edentata, characterized by having the carapace composed of a solid piece (formed by the union of a multitude of bony dermal plates) without any movable rings.