I o8 Memoir Sears Foundation for Marine Research 



Generic Characters. Disc ranging from a little broader than long to a little longer 

 than broad, its anterior margin broadly rounded; outer margin from continuously 

 rounded to weakly concave a little posterior to level of spiracles; posterior contours 

 of pectorals either curving inward and forward to junction with trunk or merging insen- 

 sibly rearward with sides of latter. Snout in front of eyes rigid to the touch nearly to 

 anterior margin. Tail with a ribband-like membranous fold along each side, its length 

 from tips of pelvics more than six times as great as breadth of mouth, its length from 

 center of cloaca greater than distance from center of cloaca to mouth. Margins of 

 pectorals without papillae, spinous or otherwise. Origin of first dorsal over or slightly 

 posterior to rear ends of bases of pelvics. Pelvics with outer corners ranging from 

 subangular to broadly rounded, their distal margins from weakly convex to more or 

 less deeply concave,"' their inner posterior margins either united with sides of tail to 

 their tips or free from sides of tail for a shorter or longer distance in both sexes ;ii'' males 

 with a considerable area of loose flabby skin in the axil of each pelvic fin. Eye fully 

 developed, as large as spiracle in some species, smaller in others. Spiracles either close 

 behind eyes or separated from them by a moderate interspace, their length at least Vs as 

 great as distance between spiracles, their margins either smooth or more or less cor- 

 rugated or with papillae. Nuchal region with a pair of large mucous pores, close together 

 side by side. Nostrils slightly oblique, apparently minute on cursory appearance because 

 they are roofed inwardly by the joint nasal curtain, but actually they are about as long 

 as the breadth of the isthmus between them, or longer. Nasal curtain much broader 

 than long, extending to mouth; posterior margin of nostril also somewhat expanded 

 outwardly as a low flap, directed toward the mouth. Mouth narrow, transverse, ap- 

 proximately straight, and protractile as a short tube, flattened dorsoventrally.^^^ Teeth 

 with one sharp cusp. Tooth bands falling considerably short of corners of mouth; 

 largely exposed when mouth is closed in some species but entirely enclosed within 

 the closed mouth in at least one (p. 123). Integument bearing teeth only loosely 

 attached to jaws. Upper and lower jaw cartilages broad, their lateral articulations ex- 

 tensive in area and very firm; a special labial cartilage of two subtriangular elements 

 on either side of mouth; proximal end of upper element attached to upper jaw car- 

 tilage, that of lower element to lower jaw cartilage, about midway between symphysis 



1 831) in "form of body, margin of nasal valves, in having a wider skull and different cartilages" (Whitley, Fish. 

 Aust., J, 1940: 164). But the first two differences are not greater than is to be expected between species of a genus 

 with a geographical range as wide as that of Narcine. Nor does a somewhat wider skull seem important. Also, the 

 absence of small intermediate cartilaginous elements between rostral and antorbital cartilages and of a transverse 

 foramen in the anterior part of the rostral cartilage in A^. tasmaniensis, compared with their presence in N. brasiliensis, 

 seems more appropriate as a specific than as a generic character. 



109. The original illustration of N. tasmaniensis (Richardson, Trans, zool. Soc. Lond., J, 1849: pi. 2, fig. 2) shows the 

 distal margins of the pelvics as so deeply concave that the posterior part of each fin appears as a distinct lobe. But 

 seemingly this was an exaggeration, for they are represented as only weakly concave in a recent picture of this 

 same species (Whitley, Fish. Aust., i, 1940: 165, fig. 186). 



no. The pelvics in some are adnata to their tips (e. g., Narcine timlei, p. 112), in others (e. g., TV. indica) the inner pelvic 

 margins are free for only a short distance, in others (e. g., N. brasiliensis) the pelvics are free for a somewhat greater 

 distance. 



III. In a specimen of N. timlei, about 34 cm long, the mouth protruded to a distance of about 35 mm (Annandale, 

 Mem. Indian Mus., 2, 1909: 44). 



