. The Bashford Dean memorial volume :. Fishes; Sharks; Fishes, Fossil. 562 Bashford Dean Meinorial Volume salts and possibly other food substances as well. The rich plexus oi vitelline capillaries will also be bathed in the fluid of the uterine cavity and they may absorb some food and oxygen from it. If this takes place in Chlamydoselachus, it must go on tor a long time, until and even after the yolk, shown m the colored Figure 49, plate V, is resorbed, and this yolk must be used up before the fish is born, else the free oceanic life ot this little shark would be very brief. THE CLOAC.\L OPENI
. The Bashford Dean memorial volume :. Fishes; Sharks; Fishes, Fossil. 562 Bashford Dean Meinorial Volume salts and possibly other food substances as well. The rich plexus oi vitelline capillaries will also be bathed in the fluid of the uterine cavity and they may absorb some food and oxygen from it. If this takes place in Chlamydoselachus, it must go on tor a long time, until and even after the yolk, shown m the colored Figure 49, plate V, is resorbed, and this yolk must be used up before the fish is born, else the free oceanic life ot this little shark would be very brief. THE CLOAC.\L OPENINGS As has been shovv'n, the oviducts at their anterior ends have openings into the ab- domen to receive the eggs set free from the ovaries. So, posteriorly the oviducts have openings into the cloaca through which the embryos, having used up their yolk masses m development, pass out to take up their free life in the sea. The lower end ot the uterus progressively diminishes in size until, as a tube considerably reduced in cross-section, it opens out on the dorsal side of the cloaca. But even here, as everywhere else in this primitive shark, are found some surprising and interesting variations. Right Cloac.^l ChTDuc^L Opekixg PREi>Oi!;.T Since the right oviduct is predominant, since its uterine portion carries the develop- ing young, and since these must pass out through its opening into the cloaca, one would expect to find that the right opening is larger and is possibly somewhat centrally placed. Hawkes (1907j first and very briefly refers to the relative sizes of the oviducal openings into the cloaca thus: "The opening of the right enlarged oviduct ... has acquired a median position, the left oviducal opening . . lymg cephalad to it"". Only this, but she gives a diagrammatic figure to make these relative positions clear —Text- figure 17 herein. Demega (1925; confirms Hawkes and writes at length. Thus he says "The right oviduct opens out by a la
Size: 1578px × 1583px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., book, bookcentury1900, booksubjectfishes, booksubjectfishesfossil
