. The Cambridge natural history. Zoology. REPRODUCTIVE ORGANS 403 former, or " gymnoarian," condition is primitive ; the latter, or " cystoariau," is secondary, and is brought about by the growth of two peritoneal folds round the ovary and the union of their margins. Into these coelomic sacs the egg-bearing or real ovarian tissue projects either in the form of processes or of trans- versely- or longitudinally-arranged plates or folds (Fig. 232, B). The testes are composed of seminal ampullae, as in Elasmo- branchs, or of radially-arranged and sometimes plexiform tubules. Fi
. The Cambridge natural history. Zoology. REPRODUCTIVE ORGANS 403 former, or " gymnoarian," condition is primitive ; the latter, or " cystoariau," is secondary, and is brought about by the growth of two peritoneal folds round the ovary and the union of their margins. Into these coelomic sacs the egg-bearing or real ovarian tissue projects either in the form of processes or of trans- versely- or longitudinally-arranged plates or folds (Fig. 232, B). The testes are composed of seminal ampullae, as in Elasmo- branchs, or of radially-arranged and sometimes plexiform tubules. Fig. 232.—Diagrams to show the structure of the testes (A) and of the ovaries (B) in a Herring. (From Cunningham.) opening into the gonoduct, as in nearly all other Fishes (Fig. 232, A). In the Cyclostomes ( Petromyzon) the eggs and sperma- tozoa are discharged from the gonads into the coelom, whence they reach the exterior through a pair of " genital pores " leading from the hinder end of the coelom into a urinogenital sinus formed by the united extremities of the two archinephrio ducts.^ Myxine has, however, but a single median pore, opening into an integumentary cloaca, which also receives the rectal and urinary orifices. Bdellostoma has two such pores communicating with a similar cloaca.^ ' Ewart, Journ. Anat. and Phys. \. 1876, p. 488. 2 Burne, Linn. Soc. Journ. Zool. xxvi. 1898, p. 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 Harmer, S. F. (Sidney Frederic), Sir, 1862- ed; Shipley, A. E. (Arthur Everett), Sir, 1861-1927. ed. [London, Macmillan and Co. , Limited; New York, The Macmillan Company
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