72 SMITHSONIAX ^[ISCELLANEOUS COLLECTIONS VOL. 'J2 



In Abel's treatment of the dentition in Patriocetus there are also 

 various doubtful points. He asserts that the complement of teeth is 

 the one which is typical of the placentalia, ii tee';h^in each jaw; but 

 it is impossible to see how he has arrived at this conclusion. The 

 best skull in question lacks the anterior part of both upper jaw and 

 mandible, and it is impossible to say how much is lacking, or how 

 many teeth were implanted in the missing parts. Of teeth fixed in the 

 jaws there are known for the most part mere stubs — sometimes noth- 

 ing but roots. Besides these there are some dissociated teeth whose 

 position in the jaws is not certain. All that can be said is that some 

 of the teeth were simply conical with single root, and that most of 

 the cheekteeth had serrate crown and double roots. Altogether there 

 is not enough known to elucidate all the details of the dentition. It is 

 not probable that Abel should be right in his belief that the teeth 

 were present in the typical number. Such a cetacean as Patriocetus, 

 the skull of which was already highly developed in the direction of 

 the most advanced whales, scarcely could have had about the same 

 dentition as the Zeuglodonts. It is much more likely that the number 

 of teeth was increased above the typical as it is or has been in all the 

 Mystacoccti and Odontoceti which are known in this respect. In 

 order to believe in Abel's representation of the facts we must see 

 more incontestable finds. (See also note 7, pp. 52-54.) 



'' (P. 23.) The asymmetry in the skull of the toothed cetaceans 

 has often been written about. Special treatises on the subject are 

 due to Pouchet (De I'asymetrie de la face chez les Cetodontes ; Nouv. 

 Arch, du Mus. d'Hist. Nat. Paris, 1886, pp. 1-16 of separate), Abel 

 (Die Ursache der Asymmetrie des Zahnwalschadels ; Sitzungsber. k. 

 Akad. Wissensch. Wien, Math.-naturw. CI., vol. iii, pt. i, 1902, 

 pp. 510-526, pi.), Kiikenthal (Ueber die Ursache der Asymmetrie 

 des Walschadels; Anat. Anzeiger, vol. 33, 1908, pp. 609-618, with 

 illustrations) and Steinmann (Ueber die Ursache der Asymmetrie 

 der Wale; Anat. Anzeiger, vol. 41, 1912, pp. 45-54, with illustra- 

 tions) ; Pouchet ancf Abel refer to various earlier papers by other 

 writers. 



As to the reason for the crookedness Pouchet says : " Nous en 

 ignorons I'origine." 



In 1893 Kiikenthal said very nearly the same : " Die physiologische 

 Ursache kennt man nicht, vielleicht ist sie in der eigenthiimlichen 

 Art der Locomotion vermittelst der Schwanzflosse zu suchen " (Ver- 

 gleich.-Anat.u. entwickelungsgesch. Untersuch. an Walthieren, pt. 2; 

 Denkschr. med.-naturwiss. Ges. zu Jena, vol. 3, pt. 2, p. 342), a 



