262 Memoir Sears Foundation for Marine Research 



the caudal fin; in schmitti this lacks any definitely outlined lower lobe, which (added to a 

 proportionately longer terminal sector) gives the fin an aspect quite different from that of 

 cams (Fig. 42). The distance between the nostrils is only about V2-V3 as great as the 

 breadth of the mouth in schmitu, but averaging more than one-half that great in canis. The 

 inner margin of the pectoral is longer relatively in schmitti (Fig. 43 C). The upper labial 

 furrow averages somewhat longer (see Proportional Dimensions) as does the interspace 

 between the pelvics and the anal. The denticles, which are otherwise similar, are so trans- 

 parent in schmitti that the pedicels are visible from the outside, which is seldom the case 

 in canis. The teeth are not distinguishable from those of canis (cf. Fig. 42 G with 42 D). 



Color. Preserved specimens are mouse-gray above and of a pale shade of the same 

 tint below (much as in preserved canis) without any conspicuous markings. 



Size. Seemingly this is a somewhat smaller species than canis, for males may mature 

 at a length of only 600 mm. 



Develof mental Stages. Not known. 



Habits. No information is available. 



Range. So far known only from Rio Grande do Sul, in southern Brazil, from Uru- 

 guay (including Maldonado), and from Buenos Aires in northern Argentina. 



Synonyms and References: 



Mustelus schmitti Springer, Proc. U.S. nat. Mus., 86, 1939: 465 (descr. of type, meas., size at maturity); 



Uruguay, and Buenos Aires, Argentina. 

 Mustelus scAmidti*^ Bigelow and Schroeder, Proc. Boston Soc. nat. Hist., 41 (8), 1940: 420, column I; pi. 



14, fig. B, 15, fig. E, 17, fig. D (meas., discus., ill., of pectoral, caudal and teeth). For other doubtful 



references, see under M. canis, p. 254. 



Family CARCHARHINIDAE 



Characters. Two dorsal fins, the ist much shorter than the caudal, its base wholly 

 anterior to origin of pelvics; caudal much less than V2 of total length, with well marked 

 subterminal notch, not lunate, but its lower anterior corner expanded as a definite lobe, 

 its axis raised but little; caudal peduncle not strongly flattened dorso-ventrally or widely 

 expanded laterally; precaudal pits more or less strongly marked; sides of trunk, anterior 

 to anal, without longitudinal ridges; inner margins of pelvics entirely separate, posterior 

 to cloaca, in both sexes; jaws not widely protrusible; 5th gill opening over or posterior to 

 origin of pectoral; gill arches without rakers, not interconnected by a sieve of modified 

 denticles; nostrils entirely separate from mouth, their anterior margins without barbel; 

 spiracles present or absent; eyes with well developed nictitating membrane within lower 

 lid, its upper edge continuous with edge of lower eyelid anteriorly, but enclosed far within 

 the latter posteriorly; labial furrows more or less developed, on one or both jaws; teeth 

 blade-like, with only i cusp, only i row functional along sides of jaws, or 2, depending on 

 the stage in their replacement; head of normal shape, not widely expanded laterally; 



41. Misprint for "schmitti." 



