610 



AMERICAN MUSEUM OF NATURAL fflSTORY 



Urogenital Syst. — Cont'd. 

 sturgeons, Amia) the oviduct has at _ its 

 front end an open ccelomic funnel, and it is 

 difficult to find adequate reason for refusing to 

 regard such oviducts as true Miillerian ducts. 

 On this interpretation the condition charac- 

 teristic of Teleosts would be due to the lips_ of 

 the oviduct becoming fused with the ovarian 

 wall, and the duct itself would be a Miillerian 

 duct as elsewhere." 



More recently Professor Kerr (Textbook, 

 1919, p. 278) in contrast with the above state- 

 ments has formulated the following views re- 

 garding the Teleostean oviduct. 



(1) The primitive oviduct or Miillerian duct 

 gradually atrophied until eventually nothing 

 was left but its external opening, the genital 

 pore. 



(2) The splanchnoccele along the ovigerous 

 surface became enclosed by peritoneal folds, 

 the anterior part of this cavity remaining fer- 

 tile, the elongated posterior portion becoming 

 sterile and serving simply as a conducting tube 

 for the ova (oviduct) . 



(3) The posterior lips of this secondary ovi- 

 duct became fused with the edges of the genital 

 pore, which thus again becomes the oviducal 

 aperture. 



These divergent views adequately represent 

 the alternative theories regarding the nature of 

 the Teleostean oviduct. 



The latter type of oviduct, considered non- 

 homologous with the Miillerian duct, has been 

 termed ovary-duct by Howes, (G. 13. 1891.1, 

 p. 551). 



Various papers describing the structure 

 and development of the oviducts in various 

 Teleosts are Bohi, U. 1904.1; Cunning- 

 ham, J. T. 1887.3; •Haller, B. 1905.1; 

 Howes, G. B. 1891.1, .2; Huxley, T. H. 

 1883.2; •Lickteig, A. 1913.1; MacLeod, 

 J. 1881.3; Nussbaum, M. 1880.1; Nus- 

 baum-Hilarowioz, J. 1915.1; Prince, E. 

 E. 1887.1; Rathke, M. H. 1820.2; 

 Schneider, G. 1894.1, 1895.2; Vogt, C. C. 

 1882.2; Weber, M. 1886.1. 



The Teleostean oviduct arises as a peri- 

 toneal derivative formed after the differen- 

 tiation of the ovary, and it subsequently be- 

 comes connected with the ovarian investment, 

 according to *Jungersen, H. F. 1889.1 

 (p. 179), who believes that the Teleostean 

 oviduct may be regarded as a modified 

 Miillerian duct. 



The view which has long been held 

 that oviducts are absent in SalmonidiB 

 (Rathke, M. H. 1820.2; Weber, M. 

 1886.1) is considered erroneous by W. C. 

 Kendall (Bull. U. S.' Bur. Fish., 1921, 

 vol. xxxvii, p. 189) , who describes an oviducal 

 trough formed by the ovarian investments. 



VARIATION 



This section includes only detailed statistical 

 studies, by the examination of large numbers 

 of individuals, on the occurrence or frequency 

 of variation in certain characters chosen for 

 study, such as the number of scales, fin rays, 

 color markings, etc. 



These studies were largely influenced by 

 the concept of Bateson with regard to discon- 

 tinuity in the origin of species. 



For references to all abnormal variations in 

 structure, see under Teratology. 



Other references to slight variations within 

 the species will be found under the various 

 families and genera. 



Materials for the study of variation. 

 •Bateson, W. 1894.1. — Method for the 

 expression of measurements. Camerano, 

 L. 1900.1, 1901.1. — Progressive reduc- 

 tion of variability. Rosa, D. 1903.1. 



Miscellaneous papers on variation. 

 Bumpus, H. C. 1898.6; Eigenmann, C. 

 H. 1892.7; Eigenmann, G. H. & Ken- 

 nedy, C. H. 1903.2; •Fatio, V. 1877.1, 

 1899.1; Heincke, F. 1892.1; Meek, S. 

 E. 1900.3; Nichols, -J. T. 1911.2, 1916.5; 

 Walton, L. B. 1907.1. 



Detailed researches on the variation in 

 various chosen characters have been made 

 as follows. — Pilchard. Bateson, W. 

 1894.3. — Flounder. •Dunoker, G. 

 1895.1, .2, 1896.1, 1900.2. — Review of 

 this work. Stead, F. B. 1897.4. — Acerina. 

 Duncker, G. 1897.1. — Siphonostoma. 

 ■A-Duncker, G. 1908.1. — Leuciscus bal- 

 teatus. Eigenmann, C. H. 1895.2. ■ — 

 Mullus. •Fage, L. 1909.1. —Mackerel. 

 Garstang, W. 1897.3, 1898.1. — Herring. 

 ■A-Heincke, F. 1877.1. — Percina caprodes. 

 •Moenkhaus, W. J. 1893.1-1898.1. — 

 Petromyzon. Rosmini, O. 1901.1. — 

 Tench. Segre, R. 1902.1. — Tri^/lidoe. 

 Tillier, L. 1879.2. — Pimephales notatus. 

 Voris, J. H. 1899.1. — Gasterosteus. Hein- 

 cke, F. Add. 1889.1. 



Meristic variation in Asymmetron and 

 Heteropleuron. Punnett, R. C. 1903.1. 



Statistical studies on fish races. Redeke, 

 H. C. 1902.1, 1912.2. 



For the recent statistical racial studies of 

 J. Schmidt, involving breeding experiments, 

 see Genetical work under Hybrids. 



VERTEBRAL COLUMN 



Comprising the development and struc- 

 ture of the notochord, the chordal sheath, 

 the arcualia, the centra and the definitive 

 vertebrae. 



For cases of paljstrophy (coalesced vertebraa) 

 notochordal reduplications, spinal curvature, 

 etc., in fishes, see below Abnormahties of skull 

 and vertebral column under Teratology. 



For the vertebral theory of skull origin, see 

 under Skull. 



For the termination of the vertebral column 

 in the tail of fishes, see below Caudal fin under 

 Fins. 



For the coalescence of the anterior vertebrae 

 with the occipital region of the skull and the 

 transformation of certain parts into the 

 Weberian ossicles, see Weberian apparatus under 

 Auditory organs. 



For the most illuminative treatise in 

 English on the development and morphology 

 of the vertebral system in aU groups of 

 fishes, see •Gadow, H. & Abbott, E. C. 

 1894.1. 



This has served as a basis for the read- 

 able chapter in •Bridge, T. W. 1904.1. 



Comprehensive treatises in German, re- 

 lating to development and morphology in all 

 groups of vertebrates. •Goette, A. 1878.1 

 and •Schauinsland, H. Add. 1905.1. 



VARIOUS TOPICS 



Papers on the notochord: development, 

 histology and histogenesis, phytogeny, etc. 

 Boeke, J. 1902.4; Henneguy, L. F. 1907.1; 



