1868,] ON IIKI'TRANCHTTS INDICUS. 373 



trical, lour being usually turned towards the centre and six towards 

 the angle of the jaw. The teeth near the corners of the mouth, in hoth 

 jaws, are simply plates of small size and disposed in short series. 



Teeth of female : — Upper jaw, a small central tooth with a more 

 or less median fang, flanked by another asymmetrical tooth on either 

 side, also with a single fang, but arising from the inner part of the 

 free border and having au outward direction. The side teeth are 

 similar in shape and (beside the principal fang, also directed 

 obliquely outwards) present smaller denticles externally, increasing 

 iu number and distinctness as the teeth recede from the centre, but 

 all pointing horizontally outwards. The first side tooth presents 

 one denticle, the second and third two each, and the three last 

 fanged teeth three denticles, with a serrature on the inner side of 

 the base of the principal tooth. Lower jaw — one central symmetrical 

 tooth, flat and quadrate at the base, with about six denticles diver- 

 ging equally on each side. The side teeth subquadrate, flat, vertically- 

 grooved below, slightly serrated on the anterior margin, and sur- 

 mounted with about six graduated denticles directed towards the 

 angle of the jaw. The teeth at the outer extremity of both jaws 

 are rudimentary plates, as in the former case. 



Diagnosis. 



Male. Female. 



Denticles diverging from au The principal faug and all 



axial line or principal fang iu the denticles diverging from the 

 each tooth. centre line of the whole jaw. 



The dimensions of the male fish, as given by Mr. Kayner, were 



as follow : — 



feet. in. 



Extreme length 5 9 



Girth 2 1 



And of the female, which was a much younger fish : — 



Extreme length 3 10 



Length of tail 1 3 



of lower lobe 4 



Girth 1 



DESCRIPTION OF PLATE XXXIII. 



Fig. 1. Represeutatiou of recent male fish. 



2 a. Portion of slvin with scales, magnified about 20 diameters, b. Scales 



seen in profile. 

 '6 a. Upper-, and b. Lower-jaw teeth of male fish. 

 4rt. Upper-, and h. Lower-jaw teeth of female. 



5. Head of female. 



6. Inferior aspect of head, showing the extent of the gill-openings. 



7. Nostril, with angular flap. 



