MORPHOLOGY OF THE COAL MEASURES AMPHIBIA. 25 



(d) The teeth of the Coal Measures Amphibia (194) are remarkably similar in the 

 various forms. They are always slender, pleurodont denticles arranged in a single 

 row on the jaws or as tubercular eruptions on the palate bones, with a large pulp- 

 cavity and the enamel often striated. The food of the creatures must have been 

 small Crustacea, worms, insects, and succulent vegetation, such as is the food of 

 the modern Amphibia. 



(e) The occiput is formed of partially ossified (465) ex- and basi-occipitals, 

 though these elements are never firmly united by ossific union. Often a pair of 

 condyles occur, one on either exoccipital. The occiput was usually, however, car- 

 tilaginous and no trace of its structure is preserved. 



(/) The mandible is usually as long as the skull and is slender. It is composed of 

 6 elements so far as known (465) ; these are the articular, the surangular, the angular, 

 the coronoid, the dentary, and the splenial. Other elements may be present, but 

 the anatomy of this portion of the animals is not very completely known. The bones 

 are sculptured and cut by lateral-line canals (458) in a few forms. Whether the 

 articular operated on an osseous or cartilaginous quadrate is unknown, though 

 certain specimens seem to indicate an osseous condition for that element. The 

 anterior symphysis was doubtless ligamentous, the halves always separating before 

 fossilization. The dentary always bears a single row of pleurodont teeth, which 

 may vary greatly in size and number. 



(g) The hyoid apparatus is well preserved in a few forms (123). Doubtless it 

 was present in all of them, though it has seldom been preserved. The condition of 

 the hyobranchial apparatus in Cocytinus gyrinoides (text-fig. 16) from the Coal 

 Measures of Linton, Ohio, seems to indicate that the species was a perennibranchiate 

 salamander (123). It is well known from the studies of Credner that the Euro- 

 pean Branchiosauria, in the young, possessed external branchiae (187) supported by 

 lateral basibranchials. The gill-arches seem to have been slightly calcified or 

 ossified in a few cases, and they supported denticle-like projections which bore 

 the gill-filaments. When the Branchiosauria had attained a length of 100 mm. 

 or more they lost their gills (187). This change was accompanied by the reduc- 

 tion of the tail, expansion of the pelvis, and increase in ossification of the skull 

 and skeletal elements. Gills have not yet been detected among the American 

 Branchiosauria. 



(//) The eye in a few species had a large amount of black pigment, as indicated 

 by the blackening of the stone in the Mazon Creek nodules. Professor Cope (107) 

 thought that this would indicate a nocturnal and crepuscular habit for these verte- 

 brates, since the pigmentum nigrum of the choroid is largely developed. Other than 

 this suggestion nothing is known of the soft parts of the head. 



(') The alimentary canal (text-fig. 7) is beautifully preserved as a cast in three 

 specimens of the American branchiosaur species Enmicrerpeton pan* inn Moodie 

 (471) from the Mazon Creek beds. The nodules which contain these interesting 

 little fossils measure less than 3 inches in long diameter. The fossil salamanders, 

 about 30 mm. in length, are preserved on their backs and occur as nearly as is 

 possible in the center of the nodule. 



