﻿508 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 102 



enlarged or stronger than the others) , and they are only slightly flex- 

 ible. This condition suggests Rhabdohlennius, and is distinctly in 

 contrast with that of Salarios and Istiblennius. The canine far back 

 on the lower jaw, typical of salariin blennies, is tiny but stout, and 

 may be one or two in the same species. Furthermore, as Norman has 

 reported, traces of more teeth in this same dentary series can be de- 

 tected. Indeed, in the genotype E. mandibularis there are six or 

 seven plainly apparent teeth on each dentary in this series, quite dis- 

 tinct from the series of labial teeth on the anterior part of the dentaries, 

 a situation quite unknown in other salariin blennies, Norman has 

 suggested, on this account, that E. mandibularis might be properly 

 placed in a separate subgenus. A study of the other species of the 

 genus has, however, inclined us to reject this suggestion. In all other 

 particulars, E. mandibularis agrees closely with the other species of 

 the genus. The types of that species are considerably larger than 

 specimens available in the other species. It is possible that these 

 latter are mostly juvenile and that the greater number of dentary 

 teeth in E. mandibidaris is simply a factor of age, representing an 

 adult condition detectable as traces of teeth noted by Norman in other 

 species. 



While the condition of the dentition might indicate a relationship 

 somewhere between Istiblennius^ Salarias^ and Bhabdoblennius, there 

 is little else that does, and no lineal phyletic connection is apparent 

 between Ecsenius and those three genera. The lack of orbital or 

 nuchal cirri, the low number of dorsal spines, the unbranched caudal 

 rays, the full membranous connection of the last anal ray to the 

 caudal peduncle, the slender genital tube of the male, the elongation 

 of one or more caudal rays well beyond the fin membrane, which is 

 normal in most species, the lack of crenulation on the lips, the pel vies 

 1,3, the short lateral line with its double, rather than single, line of 

 pores, are characters that are mostly confined to Ecsenius among the 

 salariin blennies, and, when put together, set the genus off sharply 

 from its relatives. There are other more subtle but just as definite 

 characteristics — the slender fin rays, which give an air of diaphanous 

 fragility to the vertical fins, and the anterior profile, which is either 

 vertical or even slopes backward from the forehead to the margin of 

 the upj)er lip. 



The distribution of the known specimens and species of the genus 

 is suggestive of the division of the vast tropical Indo-Pacific fish fauna 

 into subareas, illustrated by the other genera of Salariinae and other 

 families of fishes studied by the authors. Two species have been found 



