31S 



SCAXDIN'AVIAN FISHES. 



The jaw-teeth are pointed and fixed, but small and 

 >pai-se, varying from al)oiit 20 to 4 w less in either 

 jaw. Their number is sometimes the same on each 

 side, but they are usually unsymmetrical in this re- 

 spect. In the lower jaw thev are set on the inside of 

 liie margin itself, but in the upper jaw, on the other 

 hand, further in, on the inside of the intermaxillary 

 bones. The vomerine teeth are like the jaw-teeth, but 

 still fewer (from .5 to 1) and more irregular in size. 

 The outer margin of the upper phar^■ngeals is furnislied 

 with similar, but longer teeth, whereas the lower pha- 

 ryngeals are toothless. The gill-rakers are short, their 

 number on the first branchial arch being 13. 



The esophagus Avidens just behind the pharynx, 

 and runs straight back to the pylorus (fig. 84), with- 

 out forming any distinct stomach; but a short blind 



Fig. 84. Part of the intestinal canal of Trachijpterus arctictis. a: the 

 stomach, opened and with the right side folded back to show the interior: 

 b: the pyloric part of the stomach: c: the duodenum or first division of 

 the intestine; </, d: the second division of the small intestine; e: the 

 pyloric appendages, the openings of which are shown in the section of 

 tlie duodenum; /: the valve at the passage of the small intestine 

 into the rectum: (/: the rectnm. opened; li: the spleen, .\fter Reid. 



sac rises from the end of the pylorus. From the py- 

 lorus the first divi-sion of the small intestine (duodenum) 

 curves straight forward under the oesophagus, sur- 

 rounded by extremely well-developed and numerous 

 pyloric appendages. Just in front of the anterior end 

 ot the mass of pyloric appendages the small intestine 

 turns back under the former, and in a line with the 

 pylorus, M-here the spleen is also situated, passes into 

 the large intestine (rectum), which runs straight back, 



and above tlie vent, just beliind the middle of the body", 

 forms a geniculate curve down to the anal opening. 



The course of the lateral line is fairly straight, 

 but just behind the head it slopes downwards, and thus 

 comes nearer to the belh" tiian to tlie liack*. With 

 this exception it follows the direction of the s])inal 

 column, externally showing the position of the latter 

 within the liodv. Each of its plates, at least in .spe- 

 cimens less than 1 m. in length, may be armed with 

 a spine pointing in a forwai'd dii-cction. The spines, 

 however, seem as a rule to disappear with age. 



At fii'st sight the whole body, with the exception 

 of the spines belonging to the lateral line and the dorsal 

 fin, is apparently smooth, distinct, verrucose tubercles 

 appearing only at the ventral margin. But on closer 

 examination the surface of the body proves to be di- 

 vided into small squares, consisting of flat tubercles, 

 arranged in a kind of mosaic. These tubercles are 

 covered by the thin, naked epidermis, which is tin- 

 coloured, l)ut lias a silvery lustre. The ground-colour 

 is diversified h\ two or three coal-black spots, of the 

 same size as the eye or smaller, which are round or 

 oblong (in the latter case set obliquely), on the upper 

 ])art of the sides. Two of these spots belong to the 

 abdominal part, and the third, which seems to be .soon- 

 est obliterated during growth, is set on the caudal part 

 of the l)odv'. The forehead, the top of the snout and 

 the tip of the lower jaw are also black. All the fins 

 are Idood-red. 



The true home of tlie Dealfish is unquestionably 

 in the deeper, if not in tlie deepest, parts of the North 

 Atlantic. Of its manner of life at these deptlis we 

 know nothing. It is onh' h\ accident that it can come 

 into the hands of man, for our ordinary fishing-tackle 

 is useless at depths so great. Like many other deep- 

 sea fishes, however, when some fortuitous cause has 

 suddenly raised it above the depth where the pressure 

 is suitable for its organization, it is l)orne to the sur- 

 face against its will, and then floats helplessly about, 

 unable to descend again. But on one or two occasions 

 it has shown its capacity of adapting itself to water ot 

 a less depth: Nilssux states that in Norwegian Finmark 



" In the specimen from Vinga the distance between the tip of the snout and the vent is 54 fo of the length of the body, excluding 

 the caudal fin. According to Li'tken this proportion sinks, on an average, with increasing age to 51 °o, and may even be as low as 40 "<,. 



* Where the body is deepest, jus! in front of the vent, in the specimen from Vinga, the distance between the lateral line and the 

 ventral margin is 72 'i of that between it and the dorsal margin. 



*■ The distance between tlie first spot and the tip of the snout is from about 21 to 2(5 'i of the length of the body, and between 

 the second spot and the tip of the snout from about 46 to 50 % of the length of the body. In the specimen from Vinga we find a dis- 

 tinct trace of a fourth (posterior) spot. 



