1 6 Memoir Sears Foundation for Marine Research 



with persistently growing bases, each tooth representing a single enlarged dermal 

 denticle;^" these teeth are homologous not only with the rostral teeth of the Saw Sharks 

 (Pristiophoroidea) but with the dorsal fin spines of Heterodontus and of some squaloid 

 Sharks as well ; rostral teeth deeply and firmly embedded in deep sockets of the hardened 

 cartilage of the saw in all modern Sawfishes ; however, in some fossil forms (genera 

 Propristis, Sclerorynchus) they were not socketed but were seemingly attached to the 

 skin only. The saw of the Sawfishes, while resembling that of the Saw Sharks (Pristio- 

 phoroidea) very closely in general appearance, does not bear the lateral cirri characteristic 

 of the saw of the Saw Sharks. Anterior parts of pectorals fused with sides of head for- 

 ward past all five gill openings and at a higher level, but not so far forward as the 

 mouth; posterior corners of pectoral fins terminating considerably anterior to origin 

 of pelvics. Origin of first dorsal varying from considerably anterior to origin of pelvics 

 to a little posterior to rear ends of bases of latter. Second dorsal separated from first by 

 a considerable interspace. Caudal well developed, either with or without definite lower 

 lobe, its axis somewhat raised, with termination directed toward the rear margin of 

 fin some distance below upper tip. 



Eye with a rounded velum; orbit outlined below by a deep semilunar fur- 

 row, the skin of its lower half loose, described as acting like a nictitating (winking) 

 membrane. Spiracles some distance posterior to eyes, oblique, their outer ends directed 

 rearward (the reverse of what is usual among the batoids), their posterior margins 

 without ridges or folds. Nostrils entirely separate from mouth and far removed from 

 mouth, also from each other in the midzone; anterior margin expanded in a well marked 

 lobe with rounded tip. Mouth transverse, nearly straight; skin at its corners wrinkled, 

 but without well defined pits or furrows. Gill openings wholly on lower surface. Oral 

 teeth small, rounded, close-set in quincunx arrangement and very numerous,'^ with 

 several series in function simultaneously; tooth bands ovate to arcuate in cross section 

 (Fig.4K). 



Dermal denticles over body as a whole minute, flat, ovoid, comparatively uniform, 

 clothing the skin closely, including the saw; without larger thorns, tubercles, or spines. 



The saw is supported by an elongate rostral projection from the cranium. ^^ This 

 cartilage encloses 3—5 longitudinal canals as well as other spaces toward its base, and 

 it is strengthened by various calcifications, the entire outer layer immediately next to 

 the integument being hardened in this way. Although the antorbital cartilages do not 

 extend forward beyond the level of the nostrils, the anterior end of each is connected 

 with the rostral cartilage by a ligamentous band.^^ Radial cartilages of paired as well 

 as unpaired fins supplemented by much more numerous fine horny rays, the inner 



30. For a detailed account of the histology and development of the rostral teeth, with references to earlier literature, 

 see especially Engel (Zool. Jb., Anat. Abt. 29, 1909: 51-100, pis. 3-6). 



31. 70-178 series above and nearly as many below in the different species and at different stages in growth. 



32. According to Gegenbaur (Unters. Vergl. Anat. Wirbelt., 3, 1872: 91, pi. 9, fig. 7, 8), who has given the most de- 

 tailed account with which we are acquainted, this rostral extension involves a single cartilage corresponding to the 

 single rostral cartilage of the Rhinobatoidea, not three as had been believed earlier. 



33. For a general account of the head skeleton and for a comparison with other groups of batoids, see Holmgren (Acta 

 Zool. Stockh., 22, 1941: 53, 64). 



