462 PROCEEDINGS OF THE NATIONAL. MUSEUM vol.88 



I am indebted to the authorities of the United States National Mu- 

 seum, the Museum of Zoology of the University of Michigan, the 

 Field Museum of Natural History, and the Stanford University Mu- 

 seum for loans of material and to the Museum of Comparative Zoology 

 at Harvard University for permission to examine specimens in its 

 collections, as well as to Bass Biological Laboratory, for facilities for 

 carrying out the present study. I am very grateful to Earl D. Reid, 

 A. C. Weed, Prof. G. S. Myers, Dr. A. W. Herre, Frank Firth, and 

 Prof. H. B. Bigelow for assistance in making material available for 

 examination, and especially I wish to thank Drs. Leonard P. Schultz 

 and Carl L. Hubbs for their generous help, without which I would 

 have been unable to prepare this paper. 



Genus MUSTELUS Linck 



Ml'STELUS NORRISI, new species 



Holotype. — An adult male, 72.3 mm in total length, U.S.N.M. no. 

 106639, collected off Englewood, Fla., in about 3 fathoms, March 5, 

 1938, by Stewart Springer. 



Allotype. — An adult female, 825 mm in total length, U.S.N.M. no. 

 57369, collected in Sawyers Key Channel, a few miles northwest of 

 Key West, Fla., December 14, 1906, by the Orion. SLx embryos, 

 ranging iu size from 182 to 194 mm, were taken from the uterus of 

 one side, and approximately the same number were present in the 

 other side. While the embryos did not have a clearly defined pseudo- 

 placenta, they appeared to be nearly ready for birth, and these organs 

 may have been partly absorbed by the embryos. There were no 

 indications of partitions separating the embryos in the uterus. 



Paraty pes. —U.S.N.M. no. 104333; Univ. Mich. Mus. Zool. no. 

 117094 (2 specimens); Bass Biol. Lab. nos. 317, 318, 320, and 321. 



Description. — A small species (males mature at 600 mm or less in 

 contrast to those of M. canis, which become mature at 750 mm or 

 more). Form slender, tail long, back little elevated. Head rela- 

 tively narrow, flattened above; snout rounded, of moderate length. 

 A middorsal ridge in the skin extending from before the first dorsal 

 between the fins to the caudal. Fins relatively small; pectorals nar- 

 row; lower lobe of the caudal well developed and acute in full-grown 

 specimens; origin of the first dorsal behind the inner angle of the 

 pectoral. Eyes large, with diamond-shaped pupils; distance between 

 nostrils less than horizontal diameter of the orbit. Mouth small, 

 greatly arched, not broadly rounded anteriorly, the lines of occlusion 

 of the jaws forming an angle of 90° or less at the apex; outer labial 

 fold either longer or shorter than the inner, of variable length. Teeth 

 paved but with elevated blunt crowns, higher than in most species of 

 Mustelus; with several series in function, teeth of upper and lower 



