(d) Palatines 



There are no remarkable differences 

 in the overall form of the palatines among 

 the istiophorid fishes. There are, however, 

 remarkable differences in the teeth which 

 grow on the palatines, the shortnosed spear- 

 fish having several rows of fine, sharp villi- 

 form teeth, whereas in the other species 

 there are only one or two rows which are 

 poorly developed or vestigial (plate 7). 



(e) Posttemporal and supraclavicle 



The anterior portion of the post- 

 temporal is trident-shaped and articulates 

 with the cranium. Its posterior end is 

 generally rounded, but has a triangular 

 projection which extends obliquely down 

 and rearward. 



In the white marlin the posterior 

 edge is rather triangular, and in the very 

 middle of the broadest portion of the bone 

 there is a somewhat slanting, conspicuous 

 ridge, the anterior end of which projects 

 in the form of a spine. In the black marlin 

 the posterior end is rounded and the triangu- 

 lar projection is sharp. The process in the 

 c enter is blunt, but along the lower edge 

 of the bone at the base of the lowest portion 

 of the anterior projection there is another 

 small projection. In the striped marlin the 

 end of the bone is roughly rounded, the 

 central projection is rather broad, and the 

 triangular posterior projection is broad and 

 very close to the main part of the bone. The 

 central process is very conspicuous and 

 there is a deep concavity directly below it. 

 The small projection on the lower edge of 

 the bone which was seen in the black marlin 

 is also present in this species. In the sail- 

 fish the posterior part of the bone is markedly smaller and narrower than in the other species, 

 the triangular projection is large, and the central process is obscure. There is no projection 

 along the lower edge. In the shortnosed spearfish the posterior end of the bone is rather ellip- 

 tical, the triangular projection is broad and large, and instead of the central process there is a 

 somewhat oblique deep groove. 



Some differences are also to be seen in the form of the supraclavicle. In general, this 

 bone is spatulate in shape with its upper edge irregular and gradually sharpening and its lower 

 edge rounded. The central portion of the bone is somewhat constricted. 



In the white marlin the irregular upper end is rather long and twisted downward somewhat 

 and the lower end is also irregular. In the black marlin the upper end is short and the lower end 

 is nicely rounded, while the constriction of the central part is conspicuous. In the striped marlin 

 the upper end is rather like that of the white nnarlin, the lower end is nicely rounded, and the 

 central part is only slightly constricted. In the sailfish the upper end is short and the portion 

 following it is rather expanded, the constriction of the central part is conspicuous, and the lower 



Figure l.--Structure of upper jaw (from Regan). 

 Diagram showing the structure of the rostrum 

 in Acanthocybium (a), Histiophorus (b). Xiphias 

 (c), and Xiphiorhynchus (d). pm premaxillary, 

 mx maxillary, na nasal, eth ethmoid, fr frontal. 



17 



