1887.] 175 



horn. At 7 p.m. : granules clearing away from margin of embryo, 

 leaving the crenated edge, forming into segments, more discernible. 

 10 p.m. : indication of legs budding on some of them. 



Sixth day, 7 a.m. — Clear space at margin of embryo increased, so 

 that 9 ventral segments could be distinctly counted. 11 a.m. : funis 

 dwindling more into the " bird's beak " form, curved and darker. At 

 5 p.m. : the 12 segments on the ventral region can now be made out, 

 and the six thoracic legs. At 7 p.m. : everything getting more distinct, 

 with sundry outlines of the head, and even the eyespots appearing as 

 minute brown dots in clusters of six. At 11 p.m. : a slight indication 

 of incurvature of tail in the most forward specimens. 



Here I must acknowledge the kindness of Dr. T. A. Chapman, of 

 Hereford, in allowing me to see a number of drawings taken from 

 another lot of these eggs, which I had the pleasure of sending him. 

 They were 7 days in advance of those I was observing, his figures 

 commencing July 31st, being in the sixth day of incubation. In most 

 cases showing only the embryo, and taken on a large scale, with the 

 aid of a camera lucida, they give the details very plainly. Special 

 attention was given by Dr. Chapman to the segmentation, and his 

 drawings may be said to contribute to the evidence already recorded 

 in favour of the head consisting of four segments. 



Seventh day, 5.20 a.m. — The terminal segment has become ven- 

 trally incurved, gradually increasing in length. This incurvature 

 perceptibly increased in two hours more, with outline of anal segment, 

 the thoracic legs become jointed, and projecting into clear concentric 

 space, pointing towards the tail. Soon after noon, the anal segment 

 had reached to the first pair of thoracic legs, and I could plainly see it 

 advancing towards these legs, and actually push them forwards in its 

 course. At 6 p.m. the anal segment had reached quite to a level with 

 the eye spots — pressing all the thoracic legs down in its course. 

 While this has been going on, the abdominal legs have developed, and 

 now show plainly in the arch of the loop, though not so much so as 

 the thoracic legs, and taking a different direction from the torsion now 

 setting in. With this rapid growth of the dorsal region, the umbilical 

 stump has been drawn out as it were into a dark, curved, club-shaped 

 mark, following the growth onwards, and persisting as the intestine. 

 At 9 p.m. : dorsal region still extending, and now showing segmental 

 divisions corresponding with the ventral. Those most advanced show 

 the torsion of the head now taking place, by the increasing distance 

 between the eyes, both now becoming very plainly visible. 



Eiglith day, 7 a.m. — Fine dark yolk-granules are flowing over the 



