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71 



developed laniinæ in a single row. There is a distinct cleft between the hindmost, 

 gill-bearing arch (IV) and the lower pharyngeal bone (V), surrounded on both 

 margins by gill-rakers (cf. above, p. 66 (28) ). 



Behind the gullel the alimentary canal (fig. 21, 22) is at its beginning, between 

 the spinal column and the pectoral arch, a horizontal, narrow, muscular tube (oe); 

 under the front end of the swim-bladder it bends downwards somewhat and at the 

 same time widens evenly; here the strong musculature suddenly ends; on the 

 inner side the numerous, strong longitudinal folds, which characterize this part, 

 likewise cease; the continuation of the canal increases regularly in circumference 

 — like a spindle — becomes quite thin-walled, provided on the inner surface with 

 much less numerous, lower longitudinal folds often connected to form a network. 

 The canal continues still with the same shape under the swim-bladder, narrowing 

 somewhat, as far almost as the posterior end of the abdominal cavity; here it 

 bends over to the right side, passes forwards, bends again — a little in front of 

 the middle of the swim-bladder — in 

 a sling, in which the spleen (/) rests, 

 runs further posteriorly under the 

 genital organs (go) and the kidney (re) 

 and passes over with a distinctly mark- 

 ed boundary into a short rectum (r) 

 and then bends down to the anus. 

 The walls of the rectum are somewhat 

 thicker; even the hindmost part of 

 the small intestine has thicker walls 

 than the remainder and is less in diameter. The bile duct (bd) opens on the 

 under side immediately behind the boundary mentioned between the anterior, thick- 

 walled narrow part and the wide thin-walled continuation. The intestine thus 

 begins here in reality and the narrow, thick-walled anterior tube represents the 

 œsophagus and stomach. A true stomach can thus be said to be absent. There 

 is no indication of pyloric appendages. In the anterior, spindle-shaped part of the 

 intestine and for a long distance further, to a little in front of the rectum, I found 

 plentiful food in A. scutata, consisting of quite recognizable copepods, crab-larvæ 

 and similar small Crustacea. 



The liver (h) has 2 main lobes, a long one on the left, a shorter to the 

 right. The anterior part of the alimentary tract (behind the œsophagus-stomach) 

 is surrounded by both lobes of the liver; the left lobe occupies completely the first 

 winding of the intestine; seen from the left side the latter is covered over from 

 the posterior to the anterior bend by the left lobe of the liver with which it is 

 closely connected. The gall-bladder (b) lies on the dorsal side of the right lobe, 

 sunk into this in a break in its substance and the right lobe is thus divided by 

 the break into an anterior and a posterior portion. Along the middle of the inner 

 surface of the left lobe runs a large hepatic duct, accompanying the vena hepalica 



D. K. 1) Vidensk. Selsk. Skr.. 7. Riekke, mituividensU. on mathem. AM. VI. 2. 10 



Fig. 22. 

 from right .side. Lcllers a: 

 od: oviduct. 



in fi{^. !^1. /: sjileen; 



