128 HYOBEANCHIAL SKELETON" OF XENOPUS AIS'D PIPA. 



Plate H. 



Fig. 1. Xenopus IcBvis, larva, stage 1. Hyobranchial skeleton, with mandible- 

 and larynx. (X3j.) Dorsal view. 



2. Xenopus lavis, larva, stage 2. Hyobranchial skeleton, with mandible 



and larynx. ( X 4.) 



3. Xenopus Icevis, larva, stage 3. Hyobranchial skeleton, with mandible- 



and larynx. (xS^.) 



4. Pipa americana, embryo, stage 1. Hyobranchial skeleton, with man- 



dible and larynx. (X8.) Dorsal view. 

 6. Pipa mnericana, embryo, stage 2. Hyobranchial skeleton, with man- 

 dible and larynx. ( X 7.) 



6. Tipa americana, embryo, stage 3. Hyobranchial skeleton, with man- 



dible. (X7.) 



7. Pi'pa americana, embryo, stage 4. Hyobranchial skeleton, with man- 



dible. (x6.) 



8. Tipa americana, embryo, stage 5. Hyobranchial skeleton, with man- 



dible. (X6.) 



9. Vipa americana, embryo, stage 6. Hyobranchial skeleton, with man- 



dible. ( X 6.) The position of the larynx is indicated by the dotted line.. 



10. XeMo^«<s ferns, larva, stage 3. Laryngeal skeleton, dorsal view. (xl2.) 



11. Pipa americana, embryo, stage 6. Laryngeal skeleton, dorsal view. 



(X8.) 



12. Same, ventral view. 



13. Bombinator paohypus, adult female. Laryngeal skeleton, dorsal view, 



(X4i) 



Eeference letters to Plate 11. 



a. Ala, or greater wiug of the hyobranchial skeleton. 

 ar. Arytenoid cartilage. 



b. Bronchus. 

 bh. Basihyal. 



br. Bronchial cartilage. 

 cb.l. Oeratobranchial element of the first branchial arch. 

 ch. Ceratohyal. 



ch'. Median rod of cartilage in front of the hyoglossal foramen. 

 el.3. Third branchial cleft. 

 eh. Epibranchial or commissural cartilage. 

 g. Glottis. 

 g.e. Area of attachment of the m. geniohyoideus externus. 

 h. Hyoglossal foramen. 

 hb. Hypobranchial plate. 



Jc. Overhanging cartilage on the antero-external edge of the branchial basket.^ 

 v. Ligament connecting the cricoid cartilage and the posterior epiphysis of 



the thyrohyal. 

 m. Meckelian cartilage or mandible. 



p. Accessory lobe of the lung arising from the dorsal surface of the bronchus, 

 t. Thyrohyal or posterior cornu. 

 t'. Thyroid foramen. 



t Region of separation of the first oeratobranchial from the hypobranchial 

 plate. 



