FISHES OP NEW YORK 37 



MEASUBEMENTS 



Feet Inches 



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



Distance between nostrils ............................... 1*4 



Nostril to front of mouth .............................. ^ 



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 .................... 1% 



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



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



Middle of second dorsal base to top of fin ................ 2% 



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 ............................. 10^ 



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



Lower margin of pectoral ............................... 244 



Extended pectoral not quite reaching to perpendicular 



through front of dorsal. 



Ventral origin slightly behind end of first dorsal base 



Length of ventral ....................................... 3% 



Inner margin of ventral ................................. 1% 



Vent to tip of clasper ................................... 1% 



End of ventral 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 ................. 1% 



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 large, not far be- 

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



