808 PROFESSOR W. C. M'INTOSH AND MR E. E. PRINCE ON 



anterior dorsal region, and the base of the mandible, but they are very sparse on the 

 opercular and abdominal surfaces. In the region at the base of the abdomen black 

 pigment-spots are numerous, while one or two occur on the tip of the snout and along the 

 ventral margin of the myotomes. The pectoral fins form a pair of great fan-like organs 

 dotted with yellowish pigment and very minute black spots, while delicately branched 

 yellow corpuscles occur towards the free margin. No feature is more striking than the 

 great development of the pectorals; they project almost at right angles to the body, their 

 concavity being directed backward (PI. X. figs. 2, 2a). They actively move with a 

 vigorous paddle-like motion, and aid effectively in progression. 



The tail now shows dorsally and ventrally three ridges which slope in the former 

 case upward and backward, and ventrally downward and backward. The mandible 

 remains stiff, or is very slightly movable, and as' the upper jaw projects, and the mouth 

 is wide open, the appearance produced is remarkable and diagnostic. Aeration is- suffi- 

 ciently provided for by this wide and rigid oral aperture, and the energetic forward 

 movements of the fish. In a deformed specimen at this stage the urinary vesicle was 

 large, and distended with a large number of minute highly refracting granules. More- 

 over, the dorsal blood-vessel (vs) was in course of formation, since rows of comparatively 

 large cells formed a definite tract beneath the notochord (n), as was also plainly seen in 

 the larval ling (PI. XV. fig. 1). This specimen was apparently affected by hydrops 

 pericardii, for the heart was directed at right angles from the pre-hyoidean region, and 

 the venous portion formed a spindle-shaped process attached by a narrow neck to the 

 ventral pericardial wall. At this latter end of the heart large rounded globules occurred, 

 while the arterial portion was attached in front to the posterior part of the branchial 

 framework. Probably by the dragging down of the membranous attachment of the 

 venous end, its spindle-like form was acquired. The yolk is now very much reduced. 



On the following (the sixth) day, the rapid development of pigment greatly obscured 

 the internal structure of the young fish. On the eighth day the premaxillary region 

 sends out a pair of prominent knobs, theprecursors of the spinous ridge which is subse- 

 quently formed. The anus, which has probably been open a day or two, now shows a 

 distinct corrugated aperture. The rectum is often swollen, apparently with a watery 

 fluid, and its strongly folded walls contract powerfully — expelling a riband of translucent 

 mucus containing minute refracting (fatty ?) granules similar to that discharged in the 

 tanks by the adult Cyclopterus. The mouth (m, PI. IX. fig. 5) is still rigid, but widely 

 open, and the gullet leads into a pendulous, sacculated stomach immediately behind the 

 liver. Thus the course of the oesophagus behind the otocysts is backward and downward. 

 The gut leaves the upper border of the stomach, passes along the roof of the abdominal 

 cavity, and bends downward to the anus at an angle slightly less than a right angle. 

 The whole alimentary canal behind the short oesophagus is thrown into complex rugae, 

 which constantly vary with the peristaltic movements of the walls. Above the cardiac 

 end of the stomach, and surrounded by the hepatic folds, is the translucent rounded gall- 

 bladder. 



