. The Cambridge natural history. Zoology. ELASMOBRANCHII—HOLOCEPPIALI 471 transverse ridges, and no doubt belonged to a Japanese Chimaera} In neither egg-case was there any trace of tendrils. The eggs probably lie on the sea-bottom, or, when the cases have styliform prolongations, it is possible that they are implanted in the ooze. Callorhynchus (Fig. 269) is distinguished by a singular pro- longation of the rostrum, which terminates in a downwardly- directed cutaneous flap, evidently from its abundant nerve- supply an important tactile organ. A frontal clasper is present in the male. The prol
. The Cambridge natural history. Zoology. ELASMOBRANCHII—HOLOCEPPIALI 471 transverse ridges, and no doubt belonged to a Japanese Chimaera} In neither egg-case was there any trace of tendrils. The eggs probably lie on the sea-bottom, or, when the cases have styliform prolongations, it is possible that they are implanted in the ooze. Callorhynchus (Fig. 269) is distinguished by a singular pro- longation of the rostrum, which terminates in a downwardly- directed cutaneous flap, evidently from its abundant nerve- supply an important tactile organ. A frontal clasper is present in the male. The prolonged caudal axis is up-tilted, and the tail is more distinctly heterocercal than in Chimaera. The only species, G. antarcticus, is confined to the Ant- arctic basin and the South Pacific. The egg-cases of Callorhynchus differ considerably from those of Chimaera, and so large are they that one may measure 25 cm. in length, or nearly as long as the abdominal cavity of the Fish. Each case is ovoid in shape, surrounded by a wide flat margin which is covered on one side with yellow hair-like fibres, thus giving to the case a protective resemblance to a mass of seaweed (Fig. 270). In Fig. 270.—Egg-case of Callorhynchus the central part of the case there anUrcticusMiH open to show the ^ _ _ embryo and its lobed yolk - sac is a pear-shaped cavity in which (); s, dorsal spine. (Cambridge the egg or the embryo is contained. useum.) From one end of this cavity a passage, guarded by a valve, leads to the exterior, and provides for the escape of the young. While in the egg-case the nearly ripe embryo has long external gills, and its body is nearly sessile on a large and singularly lobed yolk-sac. The third genus, Harriotta, (Fig. 271),^ is remarkable for its. ^ See also an account of the egg-case of a Chimaeroid dredged from a depth of 516 fathoms in the Bay of Bengal (Wood-Mason and Alcock, Ann. Mag. Nat. Hist. (6) viii. 1891, p. 21). ^ Goods and Bean, op. cit. p. Please note
Size: 1145px × 2182px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1890, booksubjectzoology, bookyear1895
