56 Prof. M'lntosh's Notes from the 



shaped. Slow contractions occuired at intervals. Most of 

 the yolk was absorbed, and the alimentary canal formed a 

 pale band in front. The oto cysts sometimes differed in size. 

 The day after, most of the yellow cliromatophoves in some 

 were ramified, so that the colour was diffuse, but in others the 

 pigment-specks remained circular. A few small black points 

 were mingled amongst the yellow along the sides of the body. 

 At this stage the yolk was quite free from pigment. 



A few were hatched on 8rd April, and many next day. It 

 is possible tliat the conditions as regards still water and low 

 temperature may have considerably delayed hatching. A 

 specimen removed from the capsule on the latter date 

 (4th A]n-il) differs in some respects from that figured by 

 Mr. Holt, viz. a larva about half a day old, since tlie pigment 

 is not definitely marked in his sketch. Moreover, the former 

 presented no embryonic rays in the caudal; indeed, these did 

 not appear for some time. Mr. Holt's specimens therefore 

 were probably more advanced at the period of hatching. No 

 mouth is visible and the oesophagus ends blindly in front. 

 With the exception of those on the head the yellow chroma- 

 tophores are still rounded, though, as a rule, the pigment is 

 branched at or shortly after hatching. In a lateral view the 

 yellow chromatophores are grouped chiefly at the dorsal and 

 ventral margins of the muscle-plates and on the rectum; the 

 tip of the tail is devoid of them. Besides the yellow, very 

 finely ramose black pigment-corpuscles occur on the head and 

 amongst the yellow along the body, but it is not easily seen 

 after the yellow chromatophores become stellate, and in some 

 specimens it is late in appearing. The upper part of the head 

 is chiefly furnished with black pigment. A change must thus 

 ensue before the pigment is grouped into bars, for it is some- 

 what general at this stage. The luirien of the gut has not 

 entered the oblique portion of the rectum, and the pre-anal 

 region of the marginal fin is small at this stage. A more 

 advanced condition of the pigment was present in a specimen 

 (also removed from the capsule) on the 5th April. Both 

 yellow and black chromatophores are finely branched. The 

 variability in regard to the development of the pigment is 

 further shown in an example three days later, viz. 8th April, 

 in which the pigment has now been grouped in bars — that is 

 to say, at certain parts the extension of the chromatophores 

 is more pronounced than at others. Thus the head and the 

 region of the body proper have yellowish and black pigment, 

 the latter along the dorsal and ventral edges of the muscle- 

 plates, with a special area at the rectum, and three bars 

 behind the latter, that near the tip of the tail being mostly 



