109 



2 Eight (rarely 9) rays in the ventral fin: — 



i. Second spine of the first dorsal fin remarkahly prolong- 

 ed :— 



a. Scales with twelve to seventeen rows of spinelets ... M. macrolophus. 



b. Scales with five or six very short series of spinelets M. lirphotes. 



ii. Second spine of the first dorsal fin nut abnormally long ... M. Wood-Masoni. 



3 Nine rays in the ventral fin : one or more of the spinelets of the 



middle series in each scale much enlarged ... ... M. Hoskynii. 



The species of Macrurus so much resemble each other, that it will be suffi- 

 cient to describe one species and then to give only the differential points of the 

 others, leaving the points of agreement to be understood. The commonest of 

 the Indian species — M. investigatoris — may be first described. 



85. Meicrurus (Meter urus) investigatoris, Alcock. 



Macrurus investigatoris, Alcock, Ann. Mag. Nat. Hist., Not. 1889, p. 391 : Journ. As. Soc. Bengal, Vol. LXIII. 

 pt. 2, 1891, p. 126. Illdstrations of the Zoology of the Investigator, Fishes, pl. III. fig. 4. 



B. 7. D. r+ 11. A. circ. 100. P. 20-21. V. 8 (rarely 9). 



Length of the head rather over a fifth of the total. Greatest height of the 

 body (at the eminence of the first dorsal fin) equal to the length of the head 

 behind the anterior nostril. 



Snout almost as long as the eye, overlapping the mouth ; with 3 well 

 developed tubercles (median and lateral) : nostrils in a scaleless fossa, the 

 posterior much the larger. 



Major diameter of the eye 3^ in the length of the head: width of inter- 

 orbital space about two-thirds the length of the eye. 



Mouth rather small, completely inferior : the upper jaw, which overlaps the 

 lower and is about as long as the snout, about reaches to the middle of the eye. 

 Teeth in the jaws in broadish bands, none of the teeth enlarged. 



Barbel slender, hardly half as long as the eye. 



Scales on all parts except the mouth, throat, and gill-membranes. Scales 

 of the body of moderate size; each with from 9 to 13 quite similar, nearly 

 parallel, longitudinal ridges which project slightly — sometimes not at all — 

 beyond the edge of the scale. To the naked eye the ridges appear entire, but 

 they are really finely serrated. 



Five rows of scales between the last ray of the first dorsal fin and the 

 lateral line. 



First spine of the first dorsal fin rudimentary ; second spine about as long 

 as the head without the snout. 



Pectorals pointed ; as long as the head behind the middle of the eye. 



Outer ray of the ventral fins filamentous, slightly longer than the pectorals. 



