13), consisting of the sacrum (already described) and the pelvic arch, namely ilium, ischium and pubis, it follows that only birds and mammals possess a pelvis proper, whilst such is entirely absent in the Amphibia and in reptiles with the exception of some of the Dinosaurs.
In front of the acetabulum a thick process of the ilium descends to meet the pubis, and a similar process behind meets the ischium.
The pubis consists of a short anterior portion (spina pubica or pectineai process, homologous with the prepubic process of Dinosaurs) and the long and slender pubis proper (equivalent to the processus lateralis pubis of most reptiles).
The shaft of the pubis runs parallel with that of the ischium, with which it is connected by a short ligamentous or bony bridge; this cuts off from the long incisura pubo-ischiadica a proximal portion, the foramen obturatum, for the passage of the obturator nerve.
The pectineal process is variable; it may grow entirely from the pubis, or both pubis and ilium partake of its formation, or lastly its pubic portion may be lost and the process is entirely formed by the ilium.
Ilium; Is, ischium; Pb, pubis; d.l, dorso-lumbar vertebrae; Cd, caudal vertebrae; Am, acetabulum.
The last nerve which contributes to the ischiadic plexus leaves the spinal column in most birds either between the two primary sacral vertebrae, or just below the hindmost of them, and sends a branch to the pubic portion which is composed of post-ischiadic nerves, partly imbedded in the kidneys, and innervates the ventral muscles between the tail and pubis, together with those of the cloaca and copulatory organs.
The irritation is caused by the rostrum of the insect being inserted into the skin, from which the blood is rapidly pumped up. A third human louse, known as the crab-louse (Phthirius pubis) is found amongst the hairs on other parts of the body, particularly those of the pubic region, but probably never on the head.
Maxillary bordering the mouth, forming sutures with the premaxillary, prefrontal and frontal, toothless; lower jaw toothed; pubis and ischium present, the latter forming a symphysis: Glauconiidae.
Between these two extremes the other parts and organs of the body were distributed among the remaining signs of the zodiac, the neck being assigned to the Bull, the shoulders and arms to the Gemini (or twins), the breast to Cancer, the flanks to Leo, the bladder to Virgo, the buttocks to the Balance, the pubis to the Scorpion, the thighs to Sagittarius, the knees to Capricorn, and the limbs to Aquarius.
In the Ecaudata the ilium is greatly elongated and the pubis and ischium are flattened, discoidal, and closely applied to their fellows by their inner surfaces; the pelvic girdle looks like a pair of tongs.
As usual it may be divided into an ascending, transverse, and descending portion; but the middle or transverse portion is folded into a great loop, which descends as low as the pubis; so that the colon forms altogether four folds, generally parallel to the long axis of the body.