EELATION OF THE NEMERTEA TO THE VERTEBRATA. 631 



parts of the peripheral nervous system^ the corresponding re- 

 sults of Semper, Goette, van Wijhe, and Hoffmann are all in 

 the contrary direction. They have seen the nervus lateralis 

 appear as an independent product of the epiblast_, 

 arising in loco along its whole length, its formation often 

 even preceding that of the spinal nerves. These results have 

 again been fully confirmed and definitely established by the 

 latest investigator of the problem, Beard,^ who also gives a 

 detailed description and figures of the connection between the 

 nervus lateralis and the vagus ganglion, both of them so much 

 more massive and conspicuous in early embryonic stages than 

 later on. 



And now that we are attempting to find out whether there 

 is a possibility of comparing the lateral nerve-stems of lower 

 worms with the nervus lateralis of Vertebrata, we are naturally 

 led to consider, in the second place, the question whether the 

 anterior swellings of these lateral stems (the paired brain-lobes 

 of the worm) may have their morphological equivalents, their 

 remnants, in the set of anterior nervous swellings that are 

 found in the head on a level with the nervus lateralis, and 

 longitudinally coDuected with it ; viz. the variable set of 

 ganglia of the cephalic nerves. 



As to the origin of these ganglia of the cranial nerves I have 

 no observations of my own, and must rely on the data of other 

 observers. 



It is suggestive to give the opinion of the three latest in- 

 vestigators of the development of these organs in different 

 groups of Vertebrates in their own words. 



Professor A. Froriep,^ who studied Mammalian embryos, 

 writes (loc. cit., p. 35) : — " The ganglia (of facialis, glosso- 

 pharyngeus, and vagus) enter into a peculiar, very intimate 

 connection with the epiderm ;" further (p. 40), " these gangli- 

 onic connections with the epiderm must probably be regarded 



1 " The System of Branchial Sense-Organs, &c., in Ichthyopsida," ' Quart. 

 Journ. Micr. Sci.,' November, 1885, p. 95. 



2 "Ueber Anlagen von Sinnesorganen am Facialis, &c.," 'Archiv f. Anat. u. 

 Phys.,' 1885, Anat. Abth. 



VOL. XXVII, PART 4. NEW SER. X X 



