ELONIOHTIIYS PECTINATUS. 83 



posterior edge, which is crossed by siiort obhque grooves, which terminate between the 

 marginal denticulations. Head bones sculptured externally, both with granular tubercles 

 and contorted ridges, which frequently have their sides again delicately striated; 

 opercular plate long, narrow, and rather pointed below; laniary teeth strong and conical. 

 Princi{)al rays of the pectoral fin unarticulated for about a third of their length ; anal fin 

 with a rather elongated base, and becoming fringe-like posteriorly ; fin-rays striated. 



Descrijjtion. — Although no perfect specimen of this large fish has as yet been 

 found, its general proportions are pretty well shown in the specimen represented in 

 PI. XIII, fig. 1, reduced one seventh, in which unfortunately the greater part of the 

 head and the whole of the caudal fin are wanting. 



The inner snrface of the cranial roof-bones is seen in PI. XIV, fig. 1, though in 

 many places the bone has splintered off, showing the imprint of the external sculpture. 

 Noteworthy are here the longitudinal right and left elevated lines which indicate the 

 course of the main sensory or " slime " canals of the top of the head as they traverse the 

 parietal bones (/;.) and the frontals (/.). Then between the posterior margin of the 

 cranial shield atid the post-temporal element of the shoulder-girdle (/;./.) we obtain a 

 good view of the supra-temporal chain of ossicles {s.f.) so seldom seen in a palaconiscid 

 head. Of these three are shown, namely, two belonging to the left, and one, the upper 

 in the figure, belonging to the right side of the head; while traversing all these three 

 we observe an elevated line showing the course of the supra-temporal slime canal, which 

 here, as in the salmon and many other fishes, forms a transverse commissure between 

 tiie risrht and left main canals. 



Fig. \.—jElonichthys pectinatus,'Xva.<i\i9.\T; head and shoulder-girdle, restored, a^. angular; hr. 

 branchiostegal rays; cL clavicle; rf. dentary ; i.cL infraclavicle ; )»t. maxilla; 7J. uarial opening; op. 

 operculum; or. orbit; p.op. preoperculum ; p.t. post-temporal; s.cl. supraclavicle; s.o. suborbitals; 

 s.op. suboperculum ; s.t. supratemporals; x.y. supplementary plates. 



The suspensorium is very oblique, and in consequence the operculum {op.) assumes 

 a more than usually slanting position on the side of the head ; it is long, narrow, and 

 assumes a somewhat pointed contour at its lower extremity. Between its anterior 

 margin and the posterior-superior margin of the preoperculum are two accessory pieces, 

 of which the upper {x, Text fig. 1) is very narrow, and lies over the upper part of the 



