Fishes of the Western North Atlantic 1 7 



ends embracing the outer ends of the cartilaginous radials. Propterygial cartilages of 

 pectorals as well developed as metapterygials. Pelvis convex in front but without pro- 

 cesses directed forward from outer ends.^ Surfaces of gill arches smooth inward from 

 gill filaments. 



Remarks. Attention has been called repeatedly to the shark-like features of the 

 Sawfishes, i. e., to their elongated bodies, their powerful tails and caudal fins, and their 

 comparatively small pectorals. Also, their mode of locomotion is shark-like, for they 

 propel themselves through the water by powerful strokes of the rear part of the trunk 

 and caudal fin, seemingly using the pectorals for steering and especially for directing 

 their course upward toward the surface or downward toward the bottom. All their 

 fins, like those of Sharks, have horny rays as well as cartilaginous radials. But their 

 underlying structure is batoid — the fusion of their pectorals with sides of the head 

 past the gill openings, the lack of free eyelids, the union of several of their anterior 

 vertebrae which bear a wide lateral wing on either side in some, the presence of a 

 scapular cartilage connecting the two ends of the pectoral girdle across the upper side 

 of the vertebral column to which it is bound firmly by ligamentous tissue, the presence 

 of many more radial cartilages on the propterygial cartilage of the pectoral fins than 

 on the mesopterygial cartilage, and the fact that the lower jaw has no direct connec- 

 tion with the ceratohyal cartilage.''^ 



The pristoids, in short, are true batoids, just as the squatinoids are true Sharks 

 though batoid in general appearance. The saw of the Sawfish is a remarkable develop- 

 ment, however, for its only counterpart in the entire vertebrate series is the similar 

 structure developed by the Saw Sharks (Pristiophoroidea). 



Development. Ovoviviparous; in at least one species there are several embryos 

 within a single egg capsule in each uterus.^* The rostral blade, at first more or less 

 soft and flexible, is developed during the later embryonic stages; it has been known 

 for more than two centuries that its lateral teeth do not project through the enclosing 

 integument until after the young are set free,^' otherwise it would hardly be possible 

 for the mother to give birth to them. But the saw becomes calcified and the teeth grow 

 very rapidly after the young commence their independent existence. ^^ For example, 

 in a 675 mm specimen of Pristis pectinatus (newborn to judge from its umbilical scar) 

 the blade is already rigid, with the tips of the teeth slightly projecting, while in a P. 

 perotteti of 865 mm (Fig. 6 A) the teeth are already about as long, relatively, as they 

 are in the adult of that species. 



Families and Genera. The modern members of the suborder resemble one another 

 so closely that they are all referred by common consent to the Pristidae. 



34. For further skeletal details, see Garman (Mem. Harv. Mus. comp. Zool., j6, 191 3: pi. 55, fig. 3; pi. 64> figs. 2-3)- 



35. For excellent illustrations of these skeletal characters, which we have verified by dissection, see Garman (Mem. 

 Harv. Mus. comp. Zool., j6, 191 3: pi. 55, fig. 3, pi. 64, figs. 2, 3). 



36. In a specimen of Pristis cuspidatus each uterus had a single egg capsule divided into four compartments, each with 

 one embryo. See Setna and Sarangdhar [Rec. Indian Mus. (194S), 46 (1-4), 1949: u, fig- 4]- 



37. "In the embryo state the sides of the snout are as smooth as the gums of a new-born infant" (Latham, Trans. Linn. 

 Soc. Lend., Zool. 2, 1794: 274; transl. from Klein, Hist. Pise. Natural., Missus 3, 1743: 12). 



38. This seems to have been remarked first by Latham (Trans. Linn. Soc. Lond., Zool. 2, 1794: 274). 



