Fishes of the Western North Atlantic 299 



Atlantic specimen being only about 36V2 inches or 930 mm. (Harv. Mus. Comp. Zool., 

 No. 702, from Rio de Janeiro, a male with large claspers).' 



Developmental Stages. The eggs, in early development, are enclosed in thin yellow 

 shells with pointed ends and are imbedded in crypt-like depressions in the walls of the 

 maternal uteri. A preliminary account" suggests that a placental connection later develops 

 between yolk-sac and mother, i.e., that the shark is truly viviparous, as are its close rela- 

 tives, S. sorrakowah and S. walbeehmi of the Indian Ocean." 



Size. Newborn specimens are usually about 275 to 400 mm. long." It appears that 

 some males may mature when only perhaps 600 mm. long, for we have seen one of 650 mm. 

 with claspers 61 mm. long (Rio de Janeiro); but in another of 660 mm. from the same 

 locality they were only 52 mm. long, while in two others of about the same size (642 and 

 650 mm.) from Florida they were 33 mm. and 30 mm. long respectively. A 20-inch speci- 

 men from Haiti weighed three pounds. 



Remarks. Opinions have differed as to whether or not the form with the longer and 

 more pointed snout deserves recognition as a distinct species (Jalandii Muller and Henle, 

 1841; see Synonyms, p. 301). Examination of the extensive series above (p. 295) shows 

 that an unbroken gradation occurs from those with longer, narrower snouts to those with 

 shorter and broader snouts. Since we have not been able to draw any sharp line between 

 them in this or in any other respect, the two extremes are included here under the one 

 specific name. But the situation still remains somewhat obscure, for while the broader- 

 snouted specimens appear to be the more common throughout the latitudinal range of the 

 combined species, north to south, the range of the narrower-snouted members appears to 

 be definitely restricted to warmer waters, being recorded only for the southern part of the 

 Gulf of Mexico, West Indies (Martinique, Guadeloupe), Pernambuco and Rio de Janeiro. 

 This raises the interesting question whether the two forms may not represent two species 

 which were originally distinct and with distinct ranges, but which have so hybridized (their 

 ranges having overlapped) that it is not possible to distinguish between them now." 



8. A reputed len^h of 2,135 mm. (Fowler, Bull. Amer. Mus. nat. Hist., 70 [1], 1936: 45) is so much larger than 

 the usual run of adults as to suggest an error. 



9. Gudger, Science, N. S. ^/, 1915 : 4.39. 



10. For accounts of the placental cord in these, see Southwell and Prashad (Rec. Indian Mus., 16, 1919: 223, pi. 17, 

 fig. I, 2, 4, 7, 8 [lualbeehmt], and 225, pi. 17, fig. 6, 9, 10 [sorrakoiuahY) 5 see also Thillayampalam (Indian 

 zool. Memoir 2, Lucknow, Scoliodon, 1928: 107, fig. 93 \^sorrakowahY) . 



11. A series of eleven newly bom specimens from Texas, with traces of the umbilical scar still visible, range from 

 280 to 407 mm. in length. 



12. In twelve specimens with the broadly-rounded snout, 410 to 930 mm. in total length, measurements are: distance 

 from tip of snout to outer corner of nostril 67 to 76% (average 71%) of the distance between outer nostrils; 

 width of head at outermost part of nostril 95 to 103^ (average 99%) of length of snout in front of mouthj 

 shortest distance from inner end of nostril to mouth 42 to 52% (average 45%) of length of snout in front of 

 mouth; distance between nostrils 65 to 73% (average 69%) of length of snout in front of mouth. 



In seven specimens with narrowly rounded snout, 544 to 660 mm. in total length, the measurements are: 

 distance from tip of snout to outer end of nostril 77 to 87% (average 83%) of distance between outer ends 

 of nostrils; width of head to outer end of nostril 78 to <)ofo (average 84%) of length of snout in front of 

 mouth; shortest distance from inner end of nostril to mouth 33 to 38% (average 35%) of length of snout 

 in front of mouth; distance between nostrils 51 to 59% (average s^fo) of length of snout in front of mouth. 



