. Text book of zoology. Zoology. 492 Vertehrata. and in some (Monotremes, Cetacea, Proboscidians, etc.), they retain tMs position tlirougliout life. In most species, however, at the close of fcetal life, or in early youth, each descends into an evagination of the ventral abdominal wall; usually the two evaginations are united externally to form a pouch-like appendage {scrotum), divided by a septum into two compartments, each containing one of the testes;. Fig. 401. Diagrammatic longitudinal section of the cloaca (or rectum) and the copulfttory organs, A of aCrocodile, B of a Monotreme, C—D of
. Text book of zoology. Zoology. 492 Vertehrata. and in some (Monotremes, Cetacea, Proboscidians, etc.), they retain tMs position tlirougliout life. In most species, however, at the close of fcetal life, or in early youth, each descends into an evagination of the ventral abdominal wall; usually the two evaginations are united externally to form a pouch-like appendage {scrotum), divided by a septum into two compartments, each containing one of the testes;. Fig. 401. Diagrammatic longitudinal section of the cloaca (or rectum) and the copulfttory organs, A of aCrocodile, B of a Monotreme, C—D of various other Mammalia. (J anus, 6 urinary bladder, cl cloaca, / corpus fibrosum, h skin, i gut, r (in A) seminal groove, in (B—D) seminal tube, s vas deferens, u urino- genital sinus (in C the de- generated portion of the sinus is dotted: w'), ur ureter.—Orig. whilst its cavity communicates with the abdomen by a duct varying in width, which is often closed in the adult.* In the Monotremes the vasa deferentia open, together with the ureters and urinary bladder, into a deep, though narrow outgrowth of the ventral wall * In some Mammalia (Inseotivora, Kodentia) the testes only lie in the scrotum during the breeding season (when they are much enlarged); at other times, in the Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Boas, J. E. V. (Johan Erik Vesti), 1855-1935; Boas, J. E. V. (Johan Erik Vesti), 1855-1935. Lehrbuch der Zoologie. London, Sampson Low, Marston
Size: 1194px × 2093px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1890, booksubjectzoology, bookyear1896
