MORPHOLOGY OF BRAIN AND SENSE ORGANS OP LtMULUS. 3 



B. The Stomodseal Nerves, p. 46. The labruni, p. 47. The an- 

 terior pons stomodsei ; the posterior pons stomodsei ; the anterior stomo- 

 dseal ganglion; the lateral stomodseal ganglia; the lateral and the median 

 sympathetic nerves of the trunk. 



C. The Convex Eyes and their Ganglia, p. 48. They do not belong 

 to the cephalic lobes, but to the mid-brain neuronieres; absence in scorpions ; 

 origin from the cheliceral segment in Linmlus ; is the organ of Tomosvary in 

 Myriapods the " anlage " of the convex eye ? Conversion of the larval optic 

 ganglion in Acilius into that of the adult ; relation of the frontal ocelli to 

 the larval ones, 



11. The Brain of Arachnids. 



A. The Cephalic Lobes, p. 50. Semicircular lobes, p. 50. Formation 

 of primitive cerebral vesicle, p. 51. Homology of the eyes of spiders and 

 scorpions, p. 51. 



B. The Mid-brain, p. 53. Homology of fore- and mid-brain of scorpions 

 vpith those of insects, p. 53. Stomodseal nerves. 



C. Development of the lateral stomodseal nerves, p. 54. 



D. Comparison of cephalic lobes of Arthropods and those of Annelids, p. 55. 



E. Are the stomodseal nerves derived from the circumoral nerves of a 

 Ccelenterate ? p. 56. 



III. Development of the Brain of Limulus, p. 57. 



A. The Cephalic Lobes of Limulus, p. 57. Ganglionic invagina- 

 tions ; origin of the cerebral hemispheres ; fusion of the two invaginations of 

 the second segment to form the parietal eye-tube, or epiphysis. 



B. The Mid- brain, p. 60. Stomodseal nerves. 



C. Later Modifications of the Brain: fate of the invaginations; 

 formation of medullary folds ; fate of the anterior neuropore, p. 61. 



Development of the Cerebral Hemispheres: the posterior lobe; 

 the anterior lateral lobe; the internal median, or corpus striatum. The 

 semicircular lobes, p. 66. Their relation to nerves of parietal eye; the 

 optic ganglia ; modification and origin of the various brain-vesicles. 



D. Comparison with Vertebrates, p. 67. The semicircular lobes 

 and the infundibulum of Vertebrates, p. 69. Changes in the position of the 

 parietal eye ; peduncles to the parietal eye of mammals. The third ventricle; 

 the lateral eyes ; explanation of choroid fissure in Vertebrates, p. 72. The 

 " iter ;" the fifth ventricle ; the fourth ventricle ; summary, p. 73. 



IV. The Parietal Eye, p. 75. 

 Endo- and ecto-parictal eyes ; origin ; four nerves to the same ; the epi- 

 physis ; the stalk of parietal eye-nerve ; the transverse tube ; the blood- 

 vessel ; comparison with Vertebrates ; nature of the epiphysis ; white pigment 



