. The anatomy of Nautilus pompilius. Nautilus. MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES. 121 Immediately beneath the buccal cone is still anotder org'an which is peculiar to the male. It was discovered by Van der Hoeven, and has since been known as Van der Hoeven's organ. It lies in a pocket formed by the ventral portion of the cephalic- sheatii ventrally, and dorsally by a fold connecting the ends of the horseshoe-shaped ridge which bears the superior labial lobes. (Text-tig. 4, V.) The organ can not be seen until the cephalic sheath has been opened, so closely does it lie under the buccal
. The anatomy of Nautilus pompilius. Nautilus. MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES. 121 Immediately beneath the buccal cone is still anotder org'an which is peculiar to the male. It was discovered by Van der Hoeven, and has since been known as Van der Hoeven's organ. It lies in a pocket formed by the ventral portion of the cephalic- sheatii ventrally, and dorsally by a fold connecting the ends of the horseshoe-shaped ridge which bears the superior labial lobes. (Text-tig. 4, V.) The organ can not be seen until the cephalic sheath has been opened, so closely does it lie under the buccal mass. Even then the oliserver can only notice that its anterior end appears to l)e formed of small lobes and is bilaterally symmetrical. In the diagram (Text-fig. i, V) it is represented, for the sake of convenience in drawing merely, as projecting at some dis- SLL a o ,^ SLL. Text-fig. 4.—Diagram of the arrangement of the tentacles of the male nautihis, viewing them from in front. .^S, antispadix: B, bneoal mass; OS, cephalic sheath, composed of the fnsed sheaths of the digital tentacles; O', preocular tentacle; O", postocular tentacle; S, spadix; SLL. superior labial lobe; V. Van der Hoeven's organ. tance from the buccal mass, which it does not actually do. Its shape is roughly outlined by the dotted line. I hope to present sufficient evidence to be convincing that Van der Hoeven's organ is the homologue of the inferior la))ial lobes of the female. superior labial lobes. The only considerable difl'ereiu-e between the superior labial tentacles of the male and those of the female is in their number. Eight tentacles are usually borne upon each superior labial lobe of the male, while twelve is the usual number upon each of lobes of the female. Less than eight tentacles may occur upon each lobe of the male, although I have never found more than this number. Two of my specimens presented only six tentacles upon each lobe; one speci- men had six upon one lobe and seve
Size: 1646px × 1518px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, bookpublisherwashingtongovtprin
