Fishes of the Western North Atlantic 167 



Size. That the Big-eyed Thresher grows as large as the Common Thresher is indi-. 

 cated by the following facts: one of our specimens was from a 12-foot mother, others have 

 been taken from a female of about the same size, and an 1 8-foot specimen has been taken 

 (teeth pictured in Fig. 26). 



Developmental Stages. An embryo of 64 mm., taken from the horny egg capsule, 

 already showing the extremely elongate caudal so characteristic of the adult, still had 

 well developed external gills and a long yolk stalk. One of 632 mm. in total length is evi- 

 dently ready for birth, since a well marked scar is alone reminiscent of the yolk stalk; this 

 resembles the young male pictured in Fig. 25, except that its eyes are somewhat larger 

 relatively, which is a characteristic common to embryo sharks; the longest gill openings 

 are about % as long as the diameter of the eye, its snout is blunter, and its pectorals are 

 narrower toward their tips. 



Habits. Nothing definite is yet known as to the habits of the Big-eyed Thresher of 

 the Atlantic. Its very large eyes and its coloration (nearly as dark below as above) suggest 

 that it is chiefly a deep-water species like its Formosan relative, profundus.^^ But it is not 

 exclusively so, for the specimen pictured in Fig. 25 was near the surface,^' and perhaps 

 others of the scanty list of captures likewise. 



Abundance and Range. The Big-eyed Thresher was first reported from Madeira 

 more than a century ago. It was not seen again until August 1941 when a female of 1 1 to 

 12 feet, containing embryos, was taken oflF Englewood on the west coast of Florida." 

 Very recently, females containing embryos (the young male pictured in Fig. 25) and an 

 1 8-foot specimen have been taken oflF the north coast of Cuba (oflF Matanzas, and near 

 Havana). We have been informed'" that the Museum Poey in Havana has a large mounted 

 specimen from Miami, Florida. No doubt the species is widespread in the tropical and 

 subtropical Atlantic. 



Synonyms and References: 



Alopecias suJ>erciliosus Lowe, Proc. zool. Soc. Lond., 8, 1840: 39 (Madeira). 



Alofias (no specific name), Springer, Copeia, /, 1943: 54 (off Englewood, Florida, brief descr., embryos, 

 comparison with vulpinus and with frojundus) . 



Alofias vulfintis (Bonnaterre), 1788 



Common Thresher 



Figures 27, 28 



Study Material. Three alcoholic specimens from Massachusetts, 1,225 to 1,315 mm. 

 long (Harv. Mus. Comp. Zool., No. 486, 706, 1166); mounted specimens, about 9 feet 

 long, from Massachusetts (Harv. Mus. Comp. Zool., No. 926), and 4 feet 5 inches long 



12. For description of the latter, see Nakamura (Mem. Fac. Sd. Agric. Taihoku., i^ [i], 1935: i). 



13. It was harpooned. 



14. Springer, Copeia, 1943: 54. We have received photographs of one of the embryos. 



15. By Luis Howell-Rivero. 



