| OCR Text |
Show 1897.] ON THE GRINDING-TEETH OE THE MANATEE. 595 BEEERENCE LETTERS. as. Angulosplenial bone. bh. Basihyal. cbr2. Second ceratobranchial. ch. Ceratohyal. d. Dentary bone. fl. .Foramen laterale in figs. 9 and 10; and in figs. 7 and 8 the sinus which later develops into the foramen. yhe. M . geniohyoideus externus. ghi. M . geniohyoideus internus. h, h', h". Parts of the anterior or hyoidean cornu. ha. Convex surface by which the ceratohyal articulates with the palatoquadrate cartilage. hbr. Hypobranchial plate. hy. M . hyoglossus. hgs. Hyoglossal sinus. m. Internal or mesial part of the mandibular cartilage of the larva. m'. Lateral part of the mandibular cartilage of the larva. mm. Mentomeckelian bone. oh. M . omohyoideus. Pl> p2> P3>P*- The four divisions of the M . petrohyoideus. pa. Processus anterior. pal. Processus antero-lateralis. ppl. Processus postero-lateralis. s. Space enclosed between the ceratohyal, basihyal, and first ceratobranchial. s'. Space enclosed between the hypobranchial plate and the proximal ends of the first and second ceratobranchials. sh. M . sternohyoideus ventralis. sh'. M . sternohyoideus dorsalis. sp1, sp3. Cartilaginous spicula of the first and third branchial arches. t. Thyrohyal. tf. Thyroid foramen. v. Ventral splint-bone. i IX. Aperture in membrane through which the glossopharyngeal nerve passes. 5. On the Number of Grinding-Teeth possessed by the Manatee. By OLDFIELD THOMAS, F.Z.S., and R. LYDEKKER, F.R.S., F.Z.S. [Received March 16, 1897.] (Flate X X X V I .) With one exception, the authors who have treated of the dentition of the Sirenians, from Cuvier in 1817 to the most recent writer on the subject, have estimated the number of cheek-teeth on each side of each jaw in this genus at from 6 to 8 to about 11 or 12. The single exception was Dr. Krauss, of Stuttgart, who, in one of his several papers on Sirenian skulls, writing solely of the method of growth of the jaw-bone, and evidently without any idea of the importance of the remark in regard to the number of teeth, says':- " Allein, vergleicht man den letzten Backenzahn eines jungen i Arch. Anat. Phys. 1862, p. 422. |
