m 



© 



Figure 7. — Rostra of the "Cylindracanthus group" A, B. Cylindracanthus rectus. C, D, E. Aglyptorhynchus venablesi 



F. Aglyptorhynchus sidcatus. (From Casier, 1966.) 



in length. It is possible that these small skulls belong 

 to one of the small spearfishes. Three species of 

 Brachyrhynchus have been described from rostra 

 found in the Eocene of Belgium and the Pliocene of 

 Italy. Woodward (1901) thought that Brachyrhyn- 

 chus was probably identical with 1 stiophorus. Based 

 upon the figures that I have seen, I agree that 

 Brachyrhynchus belongs to an extant genus of the 

 Istiophoridae. 



Most paleontologists (Woodward, 1901; Leriche, 

 1910: Casier, 1966) seem to have lumped all living 

 istiophorid species into a single genus (Istiophorus 

 or Tetrapturusj and to the best of my knowledge, 

 Fierstine and Applegate (1968) have been the only 

 paleontologists to try to place the fossils into one or 

 more of the three extant genera. Our attempt was not 

 too fruitful because of the lack of comparative os- 

 teological studies on the living forms. Nevertheless, 

 we recognized a predentary bone and a rostrum (Fig. 

 9) from the Miocene of California as belonging to 

 Makaira sp. The identifications were based on the 

 fact that these structures were much larger and more 

 massive than the similar structures in Istiophorus 

 and Tetrapturus. 



Figure 8. — Diagrams of the occipital region of several 

 scombroids and xiphioids. A. Wetherellus. B. Scom- 

 brinus. C. Acestrus sp. D. Acestrus ornatus. E. 

 Xiphiorhynchus. (From Casier, 1966.) 



Figure 9. — Makaira sp. from the middle Miocene of 

 California. Rostrum, lateral view (A) and dorsal view (B). 

 Predentary, lateral view (C) and dorsal view (D). (In part 

 from Fierstine and Applegate, 1968.) 



37 



