64 'K. KISHINOUTE. 



region of the body posterior to the sixth segment (exclusive) is formed 

 from the primitive streak. The white marginal liand (figs. 8 & 9) 

 externally observed on the preceding day was a thickening of the 

 epiblast (lat. hd.) as represented in fig. 30. 



The lateral hnmp consisted of very high colvimnar cells forming 

 a little protuberance (fig. 42). The -cells stain faintly.'. The lateral 

 hump is a ])roblematic organ which was formerly erroneously des- 

 cribed bv Kingsley^^ as the rudiment of the lateral eye. It was 

 homologised to the so-called " dorsal organ" of other Arthropods 

 by Watase.^' Kecently Patten'' and Kingsley'^ have described it as 

 serially homologous with the lateral eyes. I can not corrol)orate the 

 last two authors, as I could not find such a peculiar organ in other 

 segments, and because it a])pears at first as a protuberance and not as 

 an invagination wliich it should be, if it were homologous to the eye. 



The yolk granules in the cells of the ventral plate had mostly 

 disappeared. Late on this düy the nervous system had become 

 marked off from the general epiblast l)y a peculiar grouping of cells 

 (fig. 46). The arrangement of cells in the nervous system is just like 

 that found in tlie retina of the compound eye for the ommatidium. 

 Conical shaped groups of cells with spherical luiclei are surrounded liy 

 compressed and slender cells with long and deeply staining nuclei. 

 The top of tlie cones is directed exteriorly. The brain and the ventral 

 nerve-'MDrds are formed at the same time, ;ind are connected with eacli 

 other, though their two later.! I halves are formed independently 

 (figs. 28-30). 



On August 15th (18 days after fertilization), the cœlomic cavities 



3) Kiugsluy— V(i/c.s on the Emhrijoluitij of IJmuJux. Quart. Journal of Micro. Sc. 1885. 

 4j Watase— On the Morpholoçiy of the ( 'ompouiul Eye of Arthropode. Stud, from the Biolog. 

 Lab. Johns Hopkin's Univ. 1890. 



5) Patten— 0;( tlie Orlç/in of Vertebrates from Arachnids. Quart. Jouru. of Micro. Se. ISyO. 



6) Kingsley — 0)i tlie Phyloyeny of J/tinulus. Zool. Anz. 1890. 



