FISHES OF FAMILY BLENNIIDAE 35 



end of the respective nasal bone. The canal extends the length of each 

 nasal and enters the anterior end of each nasal's respective frontal. 

 The canal of each frontal (supraorbital) joins the other through an 

 internal opening in the median wall of each frontal in the region above 

 the orbits and, at this junction, exits to the surface of the skull by a 

 common opening formed between the frontals. Each supraorbital 

 canal then passes dorsolaterally along its respective frontal. There 

 are several openings to each supraorbital canal in the region over 

 the orbit. At the dorsoposterior end of the orbit, each canal sends a 

 branch (infraorbital) through its respective circumorbital bones, 

 with openings to the canal in some bones and between each pair of 

 bones. Each supraorbital canal extends posteriorly and joins its 

 respective pterotic canal (at its entrance into the pterotic an anterior 

 extension of the sphenotic shares with the pterotic in surrounding the 

 pterotic canal). Each pterotic canal exits at the posterior end of its 

 respective pterotic where it divides into two branches. One branch 

 passes laterally and enters the preopercle, becoming the preopercul- 

 omandibular canal. The preoperculomandibular canal extends along 

 the length of the preopercle (with five external openings) and enters 

 the articular, almost immediately passing into the dentary and again 

 exiting almost immediately from two openings in the posterior end of 

 the dentary. The other branch from the pterotic canal enters the lateral 

 extrascapular and there divides into two branches. One branch extends 

 dorsomesially (supratemporal canal) through the posterior end of 

 the parietal (with several external openings), continues to the supra- 

 occipital, where it exits as the dorsomedian opening of the skull and 

 joins the supratemporal canal from the opposite side of the skull. 

 The second branch passes from the lateral extrascapular into the 

 posttemporal and then into the supracleithrum. From the supra- 

 cleithrum the canal enters the skin of the side and continues as the 

 lateral line canal. Periodically along the lateral line, there are small 

 tubular ossifications that presumably surround the neuromasts. The 

 lateral fine is continuous to an area below the anterior portion of the 

 soft dorsal fin; thence it continues as isolated bipored tubes, ending 

 weU anterior to the caudal peduncle. 



Vertebral Column and Unpaired Fins 



Figures 10, 11 



There are 34 vertebrae (range for the species: 33-35; up to 36 in 

 other species of Entomacrodus) . The centra are amphicoelous, con- 

 stricted midlaterally, lack lateral longitudinal struts, and bear a canal 

 for the notochord. The first three centra are of about equal length 

 and shorter than the remaining centra, which are roughly equal in 



