42 



24. Thy r sites (PromethicJithys) bengalensis, Alcock. 



Thyrsites bengalensis, Alcock, Journ. Aa. Soo. Bengal, Vol. LXIII. pt. 2, 1894, p. 117, pi. vi. fig. 1 : Ilt.ustka- 

 tions of the Zoology of the Investigator, Fishes, pl. XV. fig. 10. 



This species may possibly be identical with, the T. prometheoides of Bleeker, 

 which I know only from the short description in Giinther's Catalogue. 



B.7. D.XVIII. ~- 4 LI. A.II.11-12, LI. P.14. V.I. 



Length of head two-sevenths of the total (caudal included), and twice the 

 greatest height of the body. 



The snout, which has the usual Trichiurid form, is two-fifths of the head in 

 length, and twice the diameter of the eye. The nostrils are small pores situated 

 well in front of the eye. 



The mouth is large, and the upper jaw-bones are massive : the maxilla 

 reaches to a point midway between the anterior border of the orbit and the pupil. 

 There is a single row of distant fang-like teeth in the premaxillary, which in 

 front, to the number of three or four, are of great size : the mandibular teeth are 

 similar in size form and arrangement, but only two — the front one on each side — 

 are enlarged, and these but slightly. There is a single row of small sharp distant 

 teeth on each palatine. Grill-opening extremely wide. Pseudobranchi'33 large. 



The head and body are invested in a thick silvery scaleless skin. The 

 lateral line bifurcates at the level of the 5th or 6th dorsal spine, the upper 

 branch running along the base of the dorsal fin, the lower descending with a 

 curve to the middle line, or a little ventrad of it, and then taking a somewhat 

 sinuous course to the caudal. 



The longest (middle) spines of the long first dorsal fin are two-thirds the 

 greatest body-height in length : the second dorsal, like the anal, is low and 

 short : the two spurious finlets are incompletely isolated in both fins. 



The caudal is large and deeply forked. 



The delicate pectorals are not quite half as long as the head. The ventrals, 

 which arise close together on the abdominal profile, a little in advance of the 

 pectorals, are each reduced to a single fluted spine. 



In correlation with the strong jaws and large fangs the stomach is huge, its 

 length being one-third of the total (caudal included). In the specimen dissected 

 there is a small air-bladder and seven large but delicate pyloric casta. 



Colours in spirit : burnished silver, with the mid-dorsal line, from snout to 

 caudal, blue-black : fins hyaline, the spinous dorsal with a black edge which is 

 broadest in front, the tips of the lobes of the caudal fin dusky. 



Five specimens are in the Indian Museum, from off Madras 145-250 

 fathoms, The largest specimen is 5^ inches long. 



Regd. Nos. 13518, 13520-13522, 13524. 



