266 NATURAL SCIENCE. Oct., 



connected with the enlarged larynx.' The examples furnished are 

 Rana gnppyi showing the thyrohyals alone ossified, Bomhinator with a 

 paired ossification in the basi-hyo-branchial, Pipa showing the absence 

 of the hyoid arch, and Xenopus. It is intended to add to this series 

 the branchial skeleton of a tadpole of one of the commoner Anura. 

 ' In the Urodela the hyoid arch consists of a large ceratohyal and a 

 hypohyal. There are usually four branchial arches, the first two only 

 of which persist in adult Salamandridae. The median elements 

 consist of a basi-hyo-branchial and a second basi-branchial.' The 

 series comprises Salamandra and Ainhlystoma, larva and adult, showing 

 the disappearance of the last two arches during metamorphosis, 

 Cryptohranchus showing the hyo-mandibular cartilage, Ainpliiuma and 

 Siren with four branchial arches, and Proteus and Necturus with only 

 three. 



Teeth. — ' In the tadpoles of most Anura and in Sww the jaws 

 are covered with a horny sheath. Teeth are rarely present in the 

 lower jaw of Anura. The premaxilla, maxilla and vomer are usually 

 dentigerous, and in the Urodela the palatine also. In many 

 Labyrinthodontia the teeth are marked by longitudinal folds, which 

 in some genera give a very complicated pattern as seen in transverse 

 section.' The specimens in this series consist of the horny teeth of 

 a.n A lytes tadpole, the skull of a toad showing absence of teeth, that of a 

 frog with upper teeth present, Salamandra showing the vomero- 

 palatine teeth parallel to the axis of the skull, Amblystoma showing 

 how the vomero-palatine teeth are parallel to the maxillary series in 

 the Axolotl, but are transverse to the axis of the skull in the gill-less 

 form, the skull of Spelerpes showing teeth on the parasphenoid, and 

 two teeth of Mastodonsaunis, with an enlarged drawing of the 

 transverse section. 



Respiratory System. — ' The larvae of almost all Amphibia are 

 provided with gills. These coexist with lungs in the adults of Siren, 

 Proteus and Necturus, but are lost in other forms, although in Crypto- 

 branclius and Aviphiuma the fourth branchial cleft remains permanently 

 open. The hmgs are elongated in some of the Urodela but are short 

 in the Salamanders and in the Anura. Bronchi are present in Pipa 

 and Xenopus, and a trachea in Cryptchranchus, Amphinma and the Apoda. 

 The skin of Amphibia plays an important part in respiration, 

 especially during hibernation.' By way of illustration are shown 

 tadpoles of the frog with external and with internal gills, preparations 

 of the lungs of Rana and Xenopus, a dissection of Spelerpes showing 

 absence of both lungs and gills, preparations of Proteus showing 

 presence of both lungs and gills, a larva of Salamandra aira with 

 external gills, a preparation of the lungs of an adult Salamandra, and 

 the head of a small specimen of Amphiuma showing the persistent 

 branchial cleft. 



Tongue. — ' The tongue in most Anura is large and fleshy, and 

 is attached to the floor of the mouth anteriorly while the posterior 



