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



a solid transverse column, showing, however, a core when viewed on end. Active 

 movements occur, so that the tail is sometimes drawn from left to right. 



On the ninth day the trunk has lengthened, and the tranverse chambers of the 

 notochord are much longer, leaving narrow intervening bars of the original tissue. The 

 otocysts are larger, and show two otoliths. The cavity of the mesenteron stretches from 

 the otocysts to the anal region. 



The heart pulsates faintly and irregularly at intervals on the tenth day (9th May). 

 The notochord is broken up into large and somewhat angular compartments. The 

 pigment-spots show further development. 



By vigorous movements the embryos, measuring about -^jth of an inch in length,'"* 

 emerged on the twelfth day ; but it has to be stated that in other instances, somewhat 

 later in the season, and when the temperature was higher, they issued (e.g., on June 2) 

 seven days after impregnation. They were carried about by the slightest surface- 

 currents, gently descending head foremost and again ascending by the usual wriggling 

 motion. The pigment-spots are very distinct, of a lemon-yellow colour as already 

 described,t and are grouped in two lateral bands. The liver forms a pouch-like prominence 

 on the anterior portion of the alimentary canal. On the second day the pigment had 

 increased anteriorly, forming irregular blotches on the cephalic region. On the fourth 

 day the pectorals are about twice as large as on emergence, and an anal tract is 

 forming, while in many the upward flexure of the caudal region is marked. They are 

 about ^jyth of an inch longer, and swim in small groups at the margin of the vessel. 



On the seventh and eighth days the chromatophores are finely stellate, and the 

 eye has much black pigment. The larvae are very active, though when descending they 

 often assume the reversed position. The snout is rounded and prominent ; an oral 

 aperture has appeared, and the mandible slightly projects. The basal process of the 

 pectorals is marked, and radial thickenings are formed on the fin. The anus is not yet 

 open, and no circulation is visible though the heart beats actively. The hyoid is well 

 developed, and four branchial bars are distinct. 



On the tenth day after emergence the survivors swam actively when disturbed, 

 using their large pectorals like flippers, but they often lay on the bottom. The dark 

 pigment of the eyes presents a greenish iridescence. The increase of the pigment over 

 the surface, the opening of the anus behind the scarcely visible yolk-sac, the great 

 angular development of the mandible, and the membranous opercular covering, are the 

 chief changes. The stomach shows tranverse folds, but posteriorly longitudinal ruga? 

 pass to the anal region. A dorsal elevation covered with papillae gives a peculiar outline 

 to the head. The embryos survived only a few days longer. J 



* Mr Cunningham (op. cit., p. 100) gives the length of the newly hatched larva at 2 - 66 mm. He Joes not allude 

 to the characteristic lemon-yellow coloration. 



t Page 791. 



X The stages intermediate hetween the foregoing and the succeeding are at present no doubt confused with those 

 of the flounder and other forms, especially as when brought to the surface they are generally injured, or as yet have 

 only been examined in spirit. 



