no. 3647 PERCIFORM FISHES — GOSLINE 43 



the uppermost circumorbital retains its usual superficial position 

 behind the orbit. But in Labrisomus and Blennius, this uppermost 

 element becomes largely buried in the flesh and forms what appears to 

 be a cranial bone rather than a member of the circumorbital series 

 (Springer, 1966). 



Once again, however, it must be noted that consolidation of the 

 circumorbital series is not a universal feature in the tropical blennies, 

 congrogadoids, and trachinoids. Indeed, in the clinid blenny Exerpes 

 asper, the circumorbital chain is widely incomplete, being represented 

 anteriorly only by an isolated lacrimal (Springer, 1955). 



Jaw apparatus. — There is no supramaxillary in the Blennioidei. 



In forms with relatively long premaxillary pedicels, there seems 

 to be two kinds of jaw protrusion. In one, represented by Congrogadus, 

 the pedicels are stout and affixed firmly to the toothed portions. In 

 such fishes, protrusion of the upper jaw may be great, but there is 

 little possibility of expanding the gape laterally. A different system 

 occurs in most trichonotids and in certain of the tropical blennies. 

 Here, the premaxillary pedicel is hinged at its base with the result 

 that the distal ends of the premaxillaries can expand outward at the 

 same time the whole bone is protruded forward. 



In the zoarceoids especially but also in the unrelated gobiesocid 

 and batrachiform fishes, the toothed portion of the premaxillary is 

 relatively short, with the maxillary extending well out behind it. 

 Indeed, in such a zoarceoid as Anarhichas, it cannot be said that the 

 maxillary is excluded from the gape. 



Opercular and hyoid apparatus.— Opercular armature is un- 

 common in the Blennioidei. 



As in other bottom fishes, water tends to be expelled from the upper 

 portion of the gill cavity. Among many of the Blennioidei there is a 

 special valve for this purpose (Makushok, 1958, pp. 20, 21, fig. 8). 

 By contrast, the gill openings usually are restricted more or less be- 

 low, with the gill membranes attached to one another across the 

 isthmus or broadly attached to the isthmus. The trachinoids and the 

 notothenioid families Trichonotidae (sensu lato) and Bovictidae 

 are exceptional in having the gill openings extending far forward. 

 The trachinoid fishes (Gill, 1907) and at least some trichonotids 

 bury themselves up to the eyes in sand or mud. Baglioni (1908) 

 has shown that Trachinus and Uranoscopus, at least, pump water 

 over the gills by sliding the branchiostegal membranes up and down 

 over the cleithral region. Inasmuch as the branchiostegals of these 

 fishes and of such trichonotids as Crystallodytes (Gosline, 1963) are 

 largely covered by the operculi, this method of breathing must cause 

 a minimum of disturbance in the surrounding sand or mud. 



