PERCIFORM FISHES — GOSLINE 



41 



Members of the Blennioidei that I have seen in life, primarily 

 tropical blennies, move forward by undulation of the body and fins; 

 even when at rest on the bottom, they maintain a sinuous body 

 configuration. 



Nasal organs. — The Blennioidei are somewhat unusual in that 

 the two nostrils have become reduced to one in two different groups. 

 All of the cold-water blennies (Zoarceoidae) have only a single nostril 

 on each side. The same is true of the Bovictidae, Nototheniidae, 

 Harpagiferidae, Bathydraconidae, and Channichthyidae, though 

 other members of the notothenioid stock, e.g., the parapercids, 

 trichonotids and cheimarrichthyids, have two on each side. Attempts 

 to relate nostril number to gross olfactory rosette structure have been 

 unsuccessful. There does, however, seem to be a correlation between 

 nostril number and geography — perhaps 90 percent of all frigid-water 

 fishes, including Blennioidei, have one nostril on each side, whereas 

 some 90 percent of all tropical fishes, including Blennioidei, have two. 



Circumorbital bones (fig. 7). — The circumorbital bones have 

 been used extensively in the classification of certain groups of Blen- 

 nioidei (e.g., Regan, 1912d; Stephens, 1963; and Springer, 1964). 

 Nevertheless, for distinguishing major groups, they must be utilized 

 with considerable circumspection. The basal percoid pattern com- 

 prises a lacrimal and five circumorbitals, the uppermost (dermophen- 

 otic) movably attached to the cranium. The second circumorbital 

 normally bears a subocular shelf in marine forms (Smith and Bailey, 

 1962). The sensory canal of the lacrimal contains several neuromast 

 organs; that of the second circumorbital, two; the other circumorbit- 

 als have a single neuromast. Among the Blennioidei, the percoid 

 pattern just described breaks down in many ways, though the basic 

 trends are only two. 



Figure 7. — Right circumorbital bones: a, Cheimarrichthys fosteri; b, Harpagifer btspinis; 

 c, Trachinus draco. Lateral views, except that in f a top view of the anterior end of 

 the series is shown below. (ds = Dermosphenotic, la — lacrimal, so = subocular shelf.) 



The first trend, occurring in most of the notothenioid and zoarceoid 

 series, is toward a disintegration of the circumorbital system. The 

 first stage in such a trend is shown by the notothenioid Para- 

 percis (Gosline, 1963, fig. 2a). There, the subocular shelf is missing 



