THE ORDERS OF TELEOSTOMOUS FISHES 477 



■difficulties of respiration in muddy water have been met by the 

 development of accessory organs enabling the fish to take oxygen 

 directly from the air. As in the case of certain Dipnoi, this 

 condition has made possible more or less amphibious or even 

 terrestrial habits, with correlated specializations for locomotion. 

 Thus Doras, one of the South American forms, moves rapidly 

 on land, "projecting itself forward on the pectoral spines by the 

 elastic spring of the tail, travelling long journeys overland from 

 one drying pond to another, spending whole nights on the way. " 

 Equally noteworthy are such bizarre forms as Malapterurus, 

 the Electric Catfish, the completely cuirassed Callichthys, 

 Chostostomus , Loricaria, the Sucking Catfish Pseudecheneis , and 

 the parasitic Bdellostoma-like Vandellia. 



Order Ostariophysi (cont'd). 



Suborder Eventognathi 1 Gill. 

 (Plectospondyli Cope in part.) 

 The Carps. 

 In the Carps the food is sucked in by the toothless protrusile 

 mouth and is masticated in the throat by the falcate toothed 

 lower pharyngeals, which thus function like the jaws of other 

 fishes. To this fact the name Eventognathi refers. In contrast 

 with the Catfishes, the Carps have no spine in the fins, the broad 

 parietals are distinct from the supraoccipital, the opercular appa- 

 ratus is complete (i. e. the suboperculum is present), scales are 

 usually present and there are no infraclavicular plates, nor an 

 adipose dorsal fin. On the other hand, a suggestive agreement 

 with the Catfishes is expressed in the naked head, the frequent 

 presence of barbels, the frequency with which the premaxillary 

 alone forms the margin of the upper jaw, and the closure of the 

 brain case laterally by the orbitosphenoids and ethmoid; while 

 further points of agreement with the Catfishes are found under the 

 •ordinal characters of the Ostariophysi (p. 473). Again, some of 

 the Loaches parallel certain of the Catfishes, in (1) the elongation 

 of the body, (2) the reduction of the scales, (3) the presence of 

 an erectile, defensive spine (in this case suborbital), (4) the 



1 ev, well, cvtos, within, yj/a#o?, jaw. 



