38 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 124 



anterior portion of the cranial roof flat or with a low arch, the inter- 

 orbital commissure of the lateralis system is broadly incomplete, 

 and the vertebrae number 26. 



Suborder Blennioidei 



The fishes united here under the Blennioidei form one of the most 

 unsatisfactory suborders of the Perciformes. The blennioids are percoid 

 derivatives that basically have taken up a mode of life in contact with 

 the bottom. This mode of life, however, has been adopted repeatedly 

 by percoid derivatives; indeed, it is the most successful of postpercoid 

 developments among fishes. All of the various fishes that live in contact 

 with the bottom have developed certain specializations in common. 

 For one thing, all of the sense organs in which perception depends on 

 ambient water tend to move toward the upper surface of the head and 

 body. More important are the changes associated with locomotion. 

 Insofar as the basal percoid must maintain at least equilibrium in a 

 fluid environment, it is always "swimming" or at least "treading 

 water." By contrast, a fish maintaining contact with the bottom is 

 basically sedentary (unless it is a continuous "grazer") and swims only 

 in short dashes from a standing start. These differences in swimming 

 requirements are reflected in fin structure. 



The problem with the bottom-living percoid derivatives is to dis- 

 tinguish the convergent characters associated with a life in contact 

 with the substrate from the indicators of similar genetic inheritance. 

 Beyond that lies the difficulty of defining groups and of separating 

 them from the basal Percoidei. 



From Linnaeus (1758) to the present, the position of the pelvic fins 

 has formed a major basis for fish classification. The majority of the 

 percoids and their derivatives have the pelvics more or less under the 

 pectorals. Most or all of the derivative forms with pelvics ahead of the 

 pectorals usually have been allocated to the Jugulares. Such a division 

 assumes that the pelvics, once they have moved forward of the pec- 

 torals, do not return. To my knowledge, this assumption is correct. 

 The question of how many different times the pelvics have moved 

 forward is more difficult. The refinements in the Jugulares proposed by 

 Boulenger (1901, 1904) and Jordan (1923) have consisted primarily in 

 excluding from the Jugulares polyphyletic elements in which anterior 

 pelvics had been developed independently. Jordan's (1923) concept of 

 the Jugulares is closest to the suborder Blennioidei, as accepted here, 

 of any classification previously proposed (see table 1). 



Since the Jugulares of Jordan and Boulenger are percoid derivatives, 

 one difficulty is to determine where the percoids end and the Jugulares 

 start. In many percoids, e.g., the Serranidae, Cepolidae, Chiasmodon- 

 tidae, and the whole series of families around the Pseudochromidae- 



