MEXICAN TAILLESS AMPHIBIANS 25 



The absurd-appearing Rhinophrynus , locally known in Mexico as 

 "poche" or "po-chi," is dark brown in life, with a yellow or orange 

 vertebral stripe in addition to smaller spots or blotches of the same 

 color. The head is narrow and unusually small for so large an animal, 

 the skin on the oval-shaped body is loose and flabby, and the limbs are 

 rather short. When disturbed the body is distended and the limbs 

 are drawn up beneath. The small nostrils are located on the top of 

 the snout, nearer the eyes than the end of the muzzle. Being noctur- 

 nal, the small eyes of this toad have vertical pupils. No vestige of an 

 external tympanum is discernible. Neither maxillary nor vomerine 

 teeth are present. Although the tongue is attached posteriorly and 

 can not be flung forward like that of the common toad, it is said to be 

 remarkably adept in licking up insects. It has a foot remarkably 

 well adapted for burrowing, with an inner horny metatarsal tubercle 

 on the calcar fully 10 millimeters in length and a secondary shovellike 

 tubercle about half as long on the end of the flrst toe. 



Correlated with its burrowing habits are certain anatomical modifi- 

 cations. Inasmuch as the rather brief published diagnoses of this 

 toad do not adequately describe its structural peculiarities, the follow- 

 ing diagnosis is given : 



Superior plate of sphenethmoid covered by the completely ossified 

 fronto-parietals; sphenethmoid septal walls ossified to end of muzzle, 

 and separating the nasals ; nasals large, entirely in contact with fronto- 

 parietals, separated by median process of the latter, and by the 

 sphenethmoid septum; pterygoid straight, thin, with a short maxil- 

 lary suture; no wing of pterygoid extending inward to parasphenoid ; 

 exoccipital nearly completely covered by parasphenoid; single fissure 

 for anterior cranial nerves; neither maxillary nor vomerine teeth; 

 no tympanum; tongue attached behind; coracoid short, expanded at 

 extremities, and slightly curved; clavicle narrow, flattened, and 

 strongly curved upward; clavicles and coracoids attached medially 

 to a single curved or epicoracoid cartilage; no omosternum; scapula 

 short and wide; suprascapula thin, constricted medially, and with 

 distal dilation; suprascapula normally in close proximity to and in 

 certain positions capable of sliding over pro-otic; humerus with flat 

 head and high Imifelike deltoid crest; radius and ulna fused; pre- 

 sacral vertebrae eight; sacral vertebra free, procoelous, and with 

 double condyle for coccyx; sacral diapophyses short, dilated; femur 

 with flat head, slender shaft, mner and outer crests on posterior surface, 

 and greatly expanded distal end; tibia and fibula fused, shorter than 

 femur; two very short, flattened metatarsals separated by median 

 oval aperture; large flattened shovellike calcar; first toe with verti- 

 cally expanded terminal phalanx; remaining terminal phalanges 

 simple. 



