THE BATRACIIIA OF NORTH AMERICA. 31 



Perruiau beds of North America, where there are five toes iu the anterior 

 foot. Iu the carpus there is at least oue intermedium, except in so;iic 

 Salainandridai and Pleurodelidse,* where it is united with the uli ar>'. 

 Centrale always present. The carpalia are five iu Cryptobrauchus and 

 Atublystoma, and three iu Plethodou and Diemyctylus. In the tarsus 

 there are three bones iu the first row, a large fibulare and intermedium, 

 and a small tibiale. There is one centrale, as in the carpus. The tarsa- 

 lia number five, except that there are four iu the Salamaudridai and 

 Pleurodelidiie, where tlie carpalia are only three. The internal or first 

 tibiale is not distal, but lateral in Amblystoma and Plethodou. It is 

 distal in Cryptobrauchus. (Plat, s 45, 4G). 



Development. — The eggs of Urodela are laid iu the water or on laud. 

 In the former case they are attached singly or in small numbers to the 

 leaves of aquatic plants. In the latter case they are laid iu little con- 

 cavities beneath stones or bark. In Desmoguathus the albumen con- 

 necting them dries into threads, which hold the eggs together. Oue of 

 the parents lies by and watches them. In the Araphiumoideaf and the 

 Apodal the female coils herself iu a circle over the eggs. 



In the growth of the larvce the branchiae and balancers are first devel- 

 o[)ed, and afterwards the anterior limbs. The posterior limbs follow. 

 Those spiracles or bianchial fissures between the epibrauchial bones 

 which support the gills give passage for water from the pharynx. There 

 are no internal gills such as are found in Anura. The branchial pro- 

 cesses vary in form, but all terminate in fringes, in each of which is a 

 vascular loop. The varieties displayed by larvse of Urodela as com- 

 pared with those of genera with permanent branchiae are as follows : 

 (Plate 2.) 



I. Septa with biiJinuate rami. 



Rami with many thread-like limbrife Siren. 



11. Septa with iiDipinnate rami. 



A rudi mental inner row of rami ; Umbrite thread-like Proteus. 



III. Septa with simple rami. 



A. Rami long, compressed : fimbriae dependent from lower edge. 



Fimbrite thread-like, extending on both outer and inner face of process. 



Kecturiis. 

 Fimbriye flat, long, chiefly confined to the lower margin of process. Lar- 

 vaj of SpeleriJes ruler ; S.Mlineaius, and GyrinoijMlus porphiiritkiis. 



Fimbria} few, subclavate Plethodou cinereus. 



AA. Rami long, narrow; bearing fimbriae only on the side next the bodj-. 



FimbriiB simple, flat, snbeqnal Amhlystoma. 



AAA. Rami very short; fimbrise extending on the vertical septa. 



FimbrisB in numerous rows on the edge of the septa ; slender, unbranched. 



Larva of Cliondroius ienehrosus. 



IV. Septa without rami. 



Septa bearing flat, thread-like fimbriae, which arise posteriorly, and are 

 often divided. Larva from Simiahmoo, Washington Territory, prob- 

 ably of a CJiondrotus. 



* E. g. Molge vulgaris (Dnges), Diemyclijlus virldescens, 

 to. P. Hay, American Naturalist, 18rf8. 

 I Sarasin, Embryology of the Cceciliidse, 



