4-1 BEEYCID^. 



streak ; snout and fins red ; the spinous dorsal violet, with rose- 

 coloiu'ed streaks. 

 Amboyna. 



a. Adult. Amboyna. From Mr. Frank's Collection. 



h. Half-grown. AmbojTia. From Mr. Frank's Collection. 



c. Adult : skeleton. Ambojnia. From Mr. Frank's Collection. 



d. Adult. Amboyna. From Mr. Stevens's Collection. 



Shehton. — The general structure of the skull is very similar 

 to that of H. ruhi'um, but ^vith such modifications as to indicate the 

 specific difference as weU as the external characters do. The narrow 

 interspace between the eyes is still more conspicuous in the skeleton. 

 The groove for the posterior processes of the intermaxillary bones 

 is very like that of H. riihrum, and extends between the principal 

 frontals, but scarcely beyond the level of the anterior margin of the 

 orbit. The fan-like expansion on the vertex is formed by seven or 

 eight radiating branches. 



The maxiUary bone is styliform at its origin only, and soon becomes 

 broader, forming a triangular plate with the posterior edge rather 

 concave and the anterior convex ; the supplementary bone is un- 

 usually developed, forming nearly one-half of the outer part of the 

 maxillary; it is crescent-shaped, with a small os interculare at its 

 upper extremity ; it is roughened by streaks, the maxillary itself 

 being smooth. The intermaxillaries are separated from one another 

 by a small notch ; they are ^ as long as the maxillaries, and have 

 posteriorly, in the midcUe of their length, a very prominent flat 

 protuberance. The mandibularies show a slight swelling in front, 

 corresponding with an accumulation of the \-iliiform teeth. 



The dentition is formed by \illiform bands only, without any 

 canines or gi-anular prominences. The bands on the jaws reach to 

 the posterior extremity of the bones ; but, whilst those of the inter- 

 maxillaries are nearly equally broad in their whole length, those of 

 the manchbularies are broadest in fi'ont and tapering behind. The 

 vomerine teeth are arranged in two naiTow and short bands, meeting 

 at a right angle ; the palatine teeth fonn a narrow band, extending 

 far on the pterygoid bone. The teeth of the pharj'ngobranchials form 

 two broad patches on each side, Avith several smaller ones besides. 



The infraorbiicd arch is rather narrow and nearly equally broad, 

 the prffiorbital widening anteriorly ; its ossification is complete ; but 

 there may be seen traces of a veiy narrow channel, covered on the 

 outside Avith streaks of a thin membrane,— a stnictirre much more 

 developed in other genera of this family and in many other fishes. 

 The lower edge of the arch is serrated. The prajorbital is strongly 

 armed with eight or nine spinous teeth, directed backwards, the 

 aaterior and posterior of v\"hich are very strong. The turbinal bone 

 overreaches the intermaxillary, with a prominent and bifurcate spine. 

 The posterior part of the hinder opening of the nostiil has two very 

 small spines, reaching into the ea\-ity ; they may be easily lost by 

 a less careful preparation of the skull. The inner parts of the 

 orbital cavity are formed as in H. t-uhnon. 



