1894.] A. Alcock — Recent Collection of Bathybial Fishes. il"? 



Family Trichiuridse. 



Thyesites, C. and V. 

 4. Thyrsites hengalensis, n. sp., PL VI., fig. I. 

 Closely related to Thyrsites prometheoides, Blkr. 



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. Pseudobranchiae large. 



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

 The lateral line bifux'cates 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 ai-e two- 

 thirds the greatest body height in length : the second dorsal, like the 

 anal, is low and short : the two spurious finlets are incompletely iso' 

 lated 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 ia a small air-bladder and seven large 

 but delicate pyloric casca. 



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. 



