56 PROCEEDINGS OF THE NATIONAL MUSEUM vol. vu 



contrast, the gill covers are more or less broadly attached to one 

 another or to the isthmus or both, and a different method of respira- 

 tion must be used. 



The tropical blennies (Blennioidae), though some members second- 

 arily have taken up a different mode of life, are fishes that basically 

 prop themselves off a hard bottom by means of one or more strength- 

 ened pelvic rays. Though the number of pelvic rays always is reduced 

 from the five usually found in the trachinids and others, the pelvics, 

 except in secondarily pelagic forms, are never rudimentary as they 

 are in the congrogadoid group. Another feature found in all but the 

 most generalized tropical blennies, i.e., the Tripterygiidae, is that 

 the uppermost pectoral ray articulates with an actinost rather than 

 the scapula. In this character, unique, to my knowledge, among the 

 Blennioidei, the tropical blennies approach the batrachoid fishes 

 (Starks, 1930). Also, the Blennioidae are the only superfamily in the 

 suborder in which a large anterior portion of the dorsal fin (or fins) 

 is made up usually of spines. 



The congrogadids, with their allies the notograptids and possibly 

 the peronedyids, are enigmatic eel-like forms. In these, the front and 

 back of the suspensorium are associated loosely. They hold with the 

 Trachinidae, alone among the Blennioidei, a subocular shelf, but this 

 is a trait inherited from the percoids. 



An attempt to establish the most generalized, i.e., percoid-like, 

 families among the Blennioidei leads down to the Parapercidae (noto- 

 thenioids), on the one hand, and the Trachinidae (trachinoid-blennioid- 

 congrogadoid series), on the other (fig. 12). Yet the percoid 

 characteristics that these two families retain are rather different. In 

 the parapercid genus Prolatilus, there is a percoid supraoccipital 

 crest and incomplete supratemporal commissure, no strut from the 

 parasphenoid extending up in front of the prootic, 10 abdominal 

 vertebrae in Parapercis, five separate hypurals (counting as in Nybe- 

 lin's 1963 system), and 15 branched caudal rays. The generalized 

 features of Trachinus, on the other hand, are the broad subocular 

 shelf and the toothed mesopterygoid of T. draco. Though the para- 

 percids and trachinids already have evolved in somewhat different 

 directions, a basal percoid family such as the Branchiostegidae coidd, 

 so far as morphology is concerned, stand at the base of both. Indeed, 

 the superficial similarities are such that it is sometimes difficult to 

 separate the members of the Branchiostegidae from the Parapercidae 

 (however, see p. 43). As for the trachinids, it is not necessary to go 

 so deeply into the percoid stock to find a fish that would provide a 

 morphologically ancestral type. Except for certain specializations, 

 e.g., fusion of elements in the caudal skeleton, Opistognathus or Acan- 

 thoclinus seem to serve fairly well. These genera already have the 



