0(3 Trans. Acad. Sci. of St. Louis. 



which I kept and observed for a long time, but one morn- 

 ing I fonnd both dead, the larger one having partly swal- 

 lowed the smaller one. They often have their gills with- 

 out fibrillae and live then by cutaneous and pulmonary 

 respiration. They are very hardy, having been frozen 

 and thawed out several times during a winter, according 

 to Mr. Samuel Kneeland. They are most active at night 

 and avoid daylight. 



Suborder MEANTES. 



This suborder may be denned as follows: Tongue, covering the floor 

 of the mouth, free in front. Jaws with a horny sheet. Vomerine teeth 

 numerous, forming two large patches converging anteriorly. Spiraculae, 

 three on each side below the gills, of which there are three on each 

 side also. Only two limbs in front. Four fingers. 



Family Sirenidae. 



Posterior legs and the pelvic bones wanting. Anterior legs with 

 three or four digits. Jaws provided with horny plates instead of teeth. 

 Vomerine teeth in two large divergent patches. Three persistent 

 branchial tufts, with three corresponding free arches across the bran- 

 chial openings and a fourth arch bound in the integument. Occipital 

 condyles sessile. Carpus cartilaginous. Vertebrae amphicoelian. 

 (Garman.) 



This family includes but two genera, both American, — 

 Pseudobranchus and Siren. Only the latter genus has so 

 far been found in the State of Missouri. 



Genus siren. 



Body long and slender. Mouth small, inferior. Tongue free in front 

 and slightly so at sides. Internal nares outside the patches of teeth. 

 Branchial tufts fimbriated. Tail short, compressed, with a dorsal mem- 

 brane. (Garman.) 



This genus includes but a single species described 

 below. 



2. Siren lacertina Linn. Siren. Two-legged Eel. Mud- 

 Eel. 



Mud Iguana, Muracna siren, Xircne lacertine, Siren operculata, Sirdne. 



Description.— Slender and eel-like. Head rather small. Eyes small. 



Snout slightly rounded, almost truncate. Nostrils inferior, near the 



