9 8 Memoir Sears Foundation for Marine Research 



the margins of its pelvics are free from the sides of the tail separates it (and its Argentine 

 representative T.puelcha Lahille 1928) from Discopyge., the western Atlantic range of 

 which is confined in any case to midlatitudes in the southern hemisphere. 



Description. Proportional dimensions in per cent of total length. Female, 720 mm 

 long, from Buzzards Bay, Massachusetts (Harv. Mus. Comp. Zool., No. 36621). 

 Male, 835 mm long, from off Plymouth, Massachusetts (Harv. Mus. Comp. Zool., 

 No. 36040). 



Disc: extreme breadth 66.(1, 65.0; length 56,0, 56.0. 



Snout length: in front of orbits 7.1, 7.5; in front of mouth 9.3, 9.1. 



Orbits: horizontal diameter 2.9, 3.0; distance between 3.9, 3.8. 



Spiracles: length 2.8, 2.6; distance between 4.9, 5.4. 



Mouth: breadth 6.7, 6.4. 



Exposed nostrils: distance between inner ends 4.3, 4.4. 



Gill openings : lengths, ist 2.5, 2.0; 3rd 3.0, 2.4; 5th 1.9, 1.8; distance between 

 inner ends, ist 15.7, 18.0; 5th 14.6, 15. i. 



First dorsal fin: vertical height 6.0, 7.2; length of base 5.8, 6.2. 



Second dorsal fin: vertical height 3.1, 4.0; length of base 3.8, 1,.^. 



Caudal fin: upper anterior margin 17.6, 18.3. 



Distance: from tip of snout to center of cloaca 58.3, 57.4; from center of cloaca 

 to tip of tail 41.7, 42.6. 



Interspace between: ist and 2nd dorsals 3.9, 4.0; 2nd dorsal and caudal 6.8, 6.6. 



Disc about 1.2 times as broad as long, its edge fleshy and thick in front but thin- 

 ning progressively rearward to posterior parts of pectorals, where it is exceedingly thin; 

 the median sector of its anterior contour nearly straight, or even slightly emarginate 

 there in some specimens; its outer margins broadly and evenly rounded, with the 

 embryonic pectoral notches persisting for a short time after birth in some European 

 specimens, hence probably in American examples also.'"' Axis of greatest breadth about 

 55—60 "/o of distance rearward from snout toward axils of pectorals. Tail from center 

 of cloaca about 67— 74 "/o as long as distance from cloaca to snout; noticeably stout 

 anteriorly, about twice as broad as deep at rear bases of pelvics, tapering thence rear- 

 ward to caudal; moderately rounded below as well as above; each side of tail a little 

 below the midlevel, with a low cutaneous fold extending from about opposite origin 

 of second dorsal rearward for a short distance beyond origin of caudal. 



Skin wholly naked above as well as below. Nuchal region with a pair of con- 

 spicuous mucous pores side by side. 



Snout in front of eyes about as long as distance between outer margins of eyes; 



70. This was the case in specimens of about 244 mm (9.66 in.) and 2S1 mm (11.06 in.) long, figured respectively by 

 Bonaparte (Icon. Faun. Ital., 3, 1835: pi. not numbered) and Rey (Fauna Iberica, Feces, i, 1928: 524, fig. i68). 

 An Irish specimen also has been described and pictured by McCoy (Ann. Mag. nat. Hist., 6, 1841: 407, 408, as 

 T. emarginata) as having notches still visible at a length of 2 feet 8 inches. But such notches have not been reported for 

 any American specimen subsequent to birth. We should point out that the indentation in the left-hand margin of 

 the disc of the specimen pictured in Fig. 22 is far posterior to the anterior limits of the pectoral, and hence it is 

 the result of deformation or injury rather than the persistence of one of the embryonic pectoral notches. 



