FISHES OF KEW YORK 37 



MEASUREMENTS 



Feet Inches 



Width of nostril ........................................ % 



Distance between nostrils ............................... 114 



Nostril to front of mouth .............................. 14 



Length of mouth opening ............................... 2% 



Width of mouth, including labial folds ................... 4 



Length of labial fold .................................... 1 



Labial fold to first gill opening .......................... 3% 



Snout to first dorsal .................................... 16 



First dorsal base ....................................... 3% 



Middle of dorsal base to top of fin ....................... 3 



Length of posterior margin of dorsal .................... !} 



From first to second dorsal .............................. 5 



Length of second dorsal base ........................... 2% 



Middle of second dorsal base to top of fin ................ 2M> 



Posterior margin of second dorsal ....................... 1% 



Second dorsal to caudal pit .............................. 3 



Caudal from pit ........................................ 12 



Lower caudal lobe ...................................... 9% 



Terminal caudal lobe ................................... 3 



Snout to pectoral, obliquely ............................. lO^/a 



Length of pectoral ..................................... 5 



Lower margin of pectoral ............................... 214 



Extended pectoral not quite reaching to perpendicular 



through front of dorsal. 



Ventral origin slightly behind end of first dorsal base 

 Length of ventral ....................................... 



Inner margin of ventral ................................. 



Vent to tip of clasper ................................... iy. 2 



End of A-eutral base to origin of anal ..................... 3% 



Anal base .............................................. 3 



Hind margin of anal .................................... 1 



Depth of anal .......................................... 2 



Anal base to origin of lower caudal lobe ................. 



Family 



Mackerel Sharks 



Genus ISURUS Rafinesque 



Body fusiform, stout; mouth wide, with long, sharp edged, 

 lanceolate, entire teeth having no basal cusps; spiracles minute 

 or absent; gill openings wide, all in advance of pectorals, lateral, 

 not extending under the throat; first, dorsal largo, not far be- 

 hind origin of pectoral; second dorsal and anal very sniall; peo- 



