FISHES OF FAMILY BLENNIIDAE 41 



Each pelvis is a laterally convex (concave inner surface) bone with 

 a thin, external, dorsoposteriorly extending triangular phlange, a 

 thicker internally extending dorsoposterior roof, and a thin, slender 

 internal blade arising from the ventral end of the roof and extending 

 to the anterior end of the pelvis (projection free at anterior end). Each 

 pelvis is closely attached to its respective cleithrum just dorsal to the 

 cleithral symphysis along the pelvis external and anterior surface. 

 Together the two pel vises form a relatively short ''pod" that fits 

 snugly in the angle formed by the anteroventral junction of the two 

 cleithra. 



Each pelvis is attached strongly to the other along the internal 

 margin of the pelvic roof and the anteriorly extending projection. 

 Anteriorly, the roof joint surfaces are appressed to each other; pos- 

 teriorly, the joint surfaces are interdigitating. Between the anterior 

 and posterior portions of the roof joint each surface indents and 

 forms half of the margin of a medial opening. Anteromedially, im- 

 mediately below the roof joint, the surface of each pelvis indents 

 to form half of the margin of another, larger opening. Just posterior 

 to this latter opening in each pelvis, there are one or two slitlike 

 foramina. Ventral to these foramina a small, thin-walled, anteriorly 

 opening pocket is formed in each pelvis. At the posterior external 

 corner of each pelvis, there is an irregular depression into which 

 the forked base of the respective pelvic fin spine is attached. A 

 thickened process extends internally from the internal face of each 

 depression. The base of the second through fourth pelvic jfin rays, 

 each a bilaterally paired structure, attach on each side to their 

 respective pelvis along a line extending internal to the depression. 

 The first pelvic fin ray base attaches to the pelvic fin spine just 

 above the spine base. Each pelvic fin spine has a forked base that 

 attaches to the pelvis. The dorsoposterior arm of each fork gives 

 rise to two separated processes. Slightly distal of its midpoint each 

 spine abruptly narrows. A broadened portion proximal to this nar- 

 rowing is the area of attachment of a broad ligament. Each half of 

 the bases of the first two pelvic fin rays bears externally directed 

 processes ; the third and fourth ray bases are unmodified. 



General Discussion of Blenniid Osteology 



Ethmoid region. — The position of the median ethmoid in relation 

 to the dorsal aspect of the skull is a relatively constant feature within 

 groups of the Blenniidae. In the Blenniini, Omobranchini, and 

 Nemophidinae the median ethmoid is the anteriormost bone of the 

 skuU and is visible when the skull is viewed dorsally (pis. 2, 4, 6, 8). 

 The median ethmoid in these groups seems to function as a brace to 

 withstand pressure from the upper jaw; it is associated with a strength- 



