56 U.S. NATIONAL MUSEUM BULLETIN 284 



the uppermost and lowermost one or two segmented rays are never 

 branched. When branched rays are present they most often number 

 nine; some species have fewer, but only individual variants of any 

 species will have as many as 10, In species with an uneven number 

 of segmented caudal rays there is always one more ray attached 

 on the upper hypural plate than to the lower. 



The number of dorsal procurrent rays varies from two (Xiphasia) 

 to 10 {Stanulus seychellensis) , but rarely exceeds eight. The ventral 

 procurrent rays vary from one (Xiphasia) to 10 (Stanulus seychel- 

 lensis), but rarely exceeds eight. Usually there is one more dorsal 

 procurrent ray than there are ventral procurrent rsijs in any specimen. 



The four basic types of caudal fin in blenniids are illustrated in 

 figure 15. The main variations from these four types are: whether 

 the caudal rays are all simple or include some branched rays, whether 

 the ventral hypural plate is autogenous or fused to the urostylar 

 vertebra (the latter condition occurs only in Enchelyurus, Laipho- 

 gnathus, and Xiphasia) , or whether the two epurals are fused together 

 (only in the single specimen of Glyptoparus, which may be 

 exceptional). 



In all blennids the anteriormost epural (a neural arch; see caudal 

 of Acanthoclinus, figure 14) is always fused to its (the penultimate) 

 vertebra and there are never more than two epurals, never less than 

 one. (This is also true of aU the comparative material of the super- 

 family Blenniicae examined except the clinid Blenniomimus cottoides, 

 which has three epurals. The northern blennioids usually have three 

 epurals.) Also in blenniids, the haemal arches of the penultimate and 

 antepenultimate vertebrae are always fused to their respective centra. 

 The hooklike process for attachment of the flexor caudalis ventralis 

 inferioris muscle is absent; this process is a marker for the haemal 

 spine portion of the ventral hypural plate (Gosline, 1960, 1961). 



The most primitive blenniid caudal is that in figure 15a (see also 

 fig. 10). This type caudal consists of two epurals, an autogenous mini- 

 mal hypural (hypural 5), a fused hypural plate and urostyle (probably 

 consisting of the urostyle, hypurals 3 and 4, and two uroneurals), 

 an autogenous ventral hypural plate (probably consisting of hypurals 

 1 and 2 and a haemal spine), and nine branched caudal rays. This 

 type caudal fin is found in most species of the Salariini (which are 

 the most specialized in dentition of the blenniids) and some species 

 of the Blenniini (Medusablennius chani, most species of Blennius). 

 There is a tendency for the minimal hypural to be decreased in size 

 in the Salariini and, based on the shape of the fused urostyle and upper 

 hypural plate, the minimal hypural would appear to be lost, rather 

 than fused, in those genera of Salariini and other blenniid taxa that 

 have no obvious minimal hypural. The other types of blenniid caudals 



