808 PROFESSOR W. C. MSINTOSH 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 (Pl. 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 
ease 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 sufhi- 
ciently provided for by this wide and rigid oral aperture, and the energetic forward 
movements of the fish. Ina 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 (7), 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, Pl. IX. fig. 5) is still gid, but widely 
open, and the gullet leads into a pendulous, sacculated stomach immediately behind the 
liver. Thus the course of the cesophagus behind the otocysts is backward and downward, 
The gut leaves the upper border of the stomach, passes along the roof of the abdominal 
eavity, and bends downward to the anus at an angle slightly less than a nght angle. 
The whole alimentary canal behind the short cesophagus is thrown into complex rug, 
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. 
