'72 Trans. Acad. Sci. of St. Louis. 



Genus ambystoma. 



Palatine teeth in a transverse, often interrupted row, sometimes in 

 tlie form of an arch or crotchet. Toes, four in front, five behind, never 

 palmate. Tongue fleshy, round or long, centrally attached, with lateral 

 and anterior margins free. Skin smooth, slimy, perforated with 

 mucous pores, especially above the orbits and in the parotid region, 

 costal furrows strongly marked. Tail rather long, compressed distally, 

 with no membranous expansion. Gular fold present. Palms and soles 

 generally with one or more tubercles. 



Synopsis of Missouei Species. 



Palatine series of teeth not extending outside the inner nares. 

 Plicae of tongue radiating from a median longitudinal groove. 

 Mandible projecting. Color blackish or brownish, with gray 

 spots on the sides. A rather slender species. 



microstomum. 



Palatine series of teeth extending outside the inner nares. Tongue 



with no longitudinal grooves, plicae radiating from behind. 



Costal grooves twelve. Two distinct plantar tubercles. Color 



brov,-n or black, with numerous yellow spots; these generally 



aggregate on the sides of the belly. tigrinum. 



Costal grooves eleven. A series of round yellow whitish spots 



on each side. Spotless below. inmctatum. 



Costal grooves eleven. Transverse gray bands on the back. A 



rather stout species. opacum. 



5. Ambystoma microstomum (Jope. Small-moutlied Sal- 

 amander. 



Amblystoma porphyriticum, Amblystoma microstomum, Chondrotus 

 microstomus. 



Description. — Palatine teeth forming a slightly angular series, with 

 convexity forward entirely between the internal nares (choanae). 

 Tongue not very large, oval, with a median longitudinal groove from 

 v/hich the plicae radiate. Head very small, very convex, slightly longer 

 than broad. Snout very short, broad, rounded, without canthus ros- 

 tralis. Lower jav/ projecting a little beyond the border of the upper. 

 Eyes moderate. Body cylindrical, much elongated, four and a half 

 times the distance from snout to gular fold. Limbs short, widely 

 separated when laid against the body; fingers and toes moderate, 

 cylindrical, depressed. Carpal and tarsal tubercles indistinct. Tail 

 as long as the head and body, or a little shorter, subcylindrical at the 

 base, becoming strongly compressed at the end, which is obtuse. Skin 

 shining, minutely pitted. No parotoids. A strong gular fold. Four- 

 teen costal grooves, extending nearly across the body, leaving the 

 middle of the back smooth. 



