205 



length of the bone and dividing the band of teeth into two. A clump of teeth 

 on the premaxillary. A row of enlarged teeth on the vomer. 



The vertical fins are well developed and confluent ; the dorsal begins a little 

 in advance of the gill-openings. 



Lateral line conspicuous. Air-bladder present. 



165. Xenomystax trucidans, Alcock. 



Xenomystax trucidans, Alcock, Journ. As. Soc. Bengal, Vol. LXIII., pt. 2, 1894, p. 134: Illustrations of the 

 Zoology of the Investigator, Fishes, pl. XVI., fig. 5. 



Length of the head, measured to the gill-opening, equal to the distance 

 between the gill-opening and the vent, or slightly more than a sixth of the total. 



The depressed and sharply pointed snout is a little more than one-third of 

 the head in length and nearly four times the major diameter of the eye : its 

 mucous pores, like those of the mandible and of the rest of the head, are large 

 slits : the anterior nostril is a large sub-tubular slit situated on the lip close to 

 the tip of the snout, the posterior is a wide elliptical foramen situated, almost 

 superiorly, partly in the posterior and partly in the middle third of the snout. 

 The mouth-cleft is wide, extending an eye-length behind the posterior border of 

 the orbit, or more than half way along the head, and the maxillae are most 

 remarkably massive. The teeth are in broad crowded bands, acicular or canini- 

 form, and for the most part depressible : those in the upper jaw are in two bands 

 — an outer very broad band of large depressible teeth in four series which 

 increase in size from without inwards, and an inner narrow band or very close- 

 set row of small rigid teeth — the two bands being separated throughout their 

 whole extent by a broad groove : the pre-maxillary teeth, which are much 

 enlarged, are in a broad patch standing outside the closed mouth : the mandi- 

 bular teeth are in at least five series increasing in size from without inwards, 

 and at the symphysis, where they are greatly enlarged, they form a patch which 

 fits into a wide notch in the upper jaw : the vomerine teeth form a short row of 

 fangs. Tongue small and intimately adherent throughout to the floor of the 

 mouth. Skin scaleless, glandular. Lateral line formed by a row of large brilli- 

 ant close-set pores. Gill-openings wide, crescentic, separated by a very narrow 

 interspace. 



Vertical fins well developed, the dorsal beginning just in advance of the 

 gill-opening. Pectorals narrow, pointed, more than half the snout in length. 



The stomach is large, extending the whole length of the abdominal cavity, 

 and is very distensible : the intestine in its posterior portion is coiled in a series 

 of close pleats : only the left lobe of the liver is developed : pancreas large : a 

 large air-bladder extending behind the vent. 



