Xiv ANATOMICAL SOCIETY OF GREAT BRITAIN AND IRELAND. 



sense organ, belonging to a series of sense organs which were originally 

 found on all the prosomatic and mesosomatic appendages, and were 

 functionally connected together as organs of co-ordination and 

 equilibration ; a series of sense organs which would, therefore, compare 

 with Eisig's lateral organs in the Capitellidse, and thus give the reason 

 why niorphologists consider the auditory organ to be a specially 

 modified branchial sense organ. 



The author further pointed out that the peculiar tissue around the 

 brain of Ammocoetes, which he has homologised with the cephalic 

 generative tissue around the brain of Limulus, passes in with the 

 auditory nerve into the cartilaginous auditory capsule. Here, and 

 here alone in the whole body, is this tissue found, except around the 

 brain and spinal cord. INIost striking is it to find that a diverticulum 

 of the generative and liver masses passes into the basal joint of the 

 last prosomatic locomotor appendage in Limulus along with the nerve 

 to the flabellum. Into this appendage, and this appendage alone, is 

 there any intrusion of this cephalic generative mass ; the coxal gland 

 passes into the basal joint of the 2nd, 3rd, 4th, and 5th locomotor 

 appendages, but not into that of the 6th. He finally suggested that 

 it was easy to conceive an animal intermediate between Limulus and 

 scorpion, which might combine the characteristics of the flabellum of 

 Limulus with supra-pectinal entochondrite of the scorpion, and thus 

 give rise to the vertebrate auditory organ, with its cartilaginous 

 capsule, into which would enter both the auditory nerve itself and the 

 nerve to the operculum — i.e., the 7th nerve. 



