GENERAL STRUCTURE AND ORDERS. IO43 



sacral vertebrae are few in number, and generally proccelous ; there 

 is but one vertebra in the sacrum ; the vertebral column terminates 

 in a long urostyle (fig. 974, ur), and there are usually no separate 

 ribs. The ilia (/') are prolonged backwards, so as to throw the 

 acetabulum far behind the sacrum ; the radius and ulna (ad), and 

 the tibia and fibula icr) are respectively fused together ; and the cal- 

 caneum and astragalus (cd) greatly elongated. There are five digits 

 in each foot, with an additional ossicle (sj>) in the pes which 

 apparently represents a prohallux. 



According to the presence or absence of the tongue this order is 

 divided into the suborders Phaneroglossa and Aglossa ; the latter 

 containing only the two families Dactylethridce and Pipidce. The 

 Phaneroglossa are subdivided into the Firmisternine and Arciferine 

 series ; the former characterised by the epicoracoids forming a band 

 connecting the coracoids (fig. 974, b), and the latter by the over- 

 lapping of the epicoracoids. Since fossil forms are but very imper- 

 fectly known, only brief mention will be made of those families 

 which have fossil representatives. 



Family Discoglossid^e. — Commencing with the Arciferine series 

 of the Phaneroglossa the present family is distinguished from those 

 that follow, and thereby approximates to the Newts, in having opis- 

 thoccelous vertebrae and rudimentary ribs. The European genus 

 Bombinator is probably represented in the Upper Miocene of Swit- 

 zerland ; although some writers have referred the fossil species to a 

 distinct genus under the name of Pelophilus. Opisthoccelous ver- 

 tebrae from the Middle Miocene of Sausan, in Gers, may belong 

 either to Bombinator or to the other existing European genus Alytes. 

 Bufavus, from the Middle Tertiary of Italy, is said to present many 

 affinities to the present family, but in the absence of ribs approxi- 

 mates to the one that follows. 



Family Pelobatid^. — This small family is characterised by the 

 presence of teeth in the upper jaw ; the absence of ribs ; and the un- 

 expanded extremity of the sacral rib. The vertebrae are usually pro- 

 ccelous, although occasionally opisthoccelous. The existing genus 

 Pelobates occurs in the Miocene of Sausan, while the imperfectly 

 known Protopelobates, from the Miocene of Bohemia, may belong 

 either to this or the next family. 



Family Pal^eobatrachid^. — This extinct family has teeth in the 

 upper jaw ; no ribs ; expanded ribs to the sacral vertebra ; and pro- 

 ccelous vertebrae. The single genus Paiceobatrachus (Probatrachus) 

 is now known to have been widely distributed over the Continent 

 during the Lower Miocene ; more than a dozen species having been 

 described. 



Family Bufonid^e. — The true Toads are characterised by the 

 total absence of teeth and dorsal ribs ; the expanded extremities of 



