60 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 119 



(first two counts listed by Springer, [1940a, p. 163]); upper teeth 

 oblique, becoming increasingly so toward corners of mouth in upper 

 jaw; teeth 6 to 9 or 10 longest, the outer teeth very low, but with 

 a definite cusp; in lower jaw, teeth 2 through 8 longest (tooth 1 not 

 markedly smaller however), the outermost two or three teeth very 

 short, round, and without a definite cusp; one or two series of teeth 

 functional in alternating rows along sides of upper jaw and two to 

 three rows along sides of lower j aw. 



Dermal denticles (examined from upper part of back beneath first 

 dorsal fin) evenly and closely spaced, overlapping but little, the blades 

 thick and rather strongly arched; length of denticle (measured to tip 

 of median marginal "tooth") less than width; small specimens mth 

 three, larger specimens usually with up to five, sharp-topped ridges, 

 and as many sharp-pointed marginal teeth (especially deep and 

 pointed in small individuals) on denticle; median tooth on denticle 

 slightly longer than more distal teeth; pedicel short and broad. 



Individuals gray or grayish brown dorsally, becoming progressively 

 more pale below; no markings on fins. 



Status of Sphyrna nana. — Sadowsky (1965) recently described a 

 new species of hammerhead, Sphyrna nana, from southern Brazil, 

 based on a single adult female, 1,330 milUmeters long. This form 

 was said to differ from S. media in having a shorter snout, a larger 

 orbit, the anterior margin of the head not regularly oval and with 

 prenarial convexities, a shorter distance between the eye and nares, 

 a shorter distance between the nares, a shorter upper caudal lobe, a 

 greater interdorsal distance, and a longer first dorsal fin base. Un- 

 fortunately, no mention was made either of the morphology of the 

 chondro cranium or of the arrangement of the mucal pores on the 

 ventral siu-face of the head. 



The following measurements were given for the holotype of S. nana: 

 Head width (190); snout to fu-st gill sht (169); snout to fu'st dorsal 

 origin (308); snout to second dorsal origin (637); distance between 

 first and second dorsal bases (233); snout to pectoral insertion (204) 

 snout to pelvic insertion (466); horizontal diameter of orbit (15) 

 length of first dorsal base (95); length of second dorsal base (43) 

 length of second dorsal lobe (45); height of second dorsal fin (37) 

 length of anal base (80); length of anal lobe (33); height of anal fin 

 (36); length of pectoral base (54); length of pelvic base (34); length 

 of caudal fin (251). If one compares these measurements with those 

 listed for S. media in table 7, it can be seen that, for those characters 

 that undergo Httle or no proportional change with an increase in total 

 body length, the values for S. nana generally fall within the range of 

 values for S. media. For those characters that undergo pronounced 



