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Mr. Van Beneden. This fact is important to be taken into 

 notice. 



In our opinion, the oculiform spot in the embryo represents 

 the nervous system, — the nervous system in its most simple 

 expression, fulfilling the act of vision, which in its lowest degree 

 of development is represented by a spot of colored pigmentum. 

 The organ of vision or perception we see here combined with 

 the sensitive organ or nervous system. 



As the embryonic development goes on, the nervous system 

 gradually appears under the oculiform spot, the spot diminishing 

 as it progresses, and disappearing when the eye specs appear on 

 the fringed edge of the outside tubes. Nervous threads have 

 been formed during that interval and now connect these super- 

 ficial organs of vision to the central mass of the nervous system. 



Thus these two organs, (that of vision and the nervous system,) 

 first combined and performing an ideal combined function in the 

 embryo, have become isolated, and each one is called upon to 

 perform its special function. 



Mr. Ayres exhibited to the Society a fish from Para, 

 Vandellia cirrhosa. 



In regard to this species the only information previously 

 recorded was, that it was sent to Prof Vandelli, of Lisbon, many 

 years since, its origin not being stated. The fish is placed by 

 Valenciennes among the Esocidse, but Mr. Ayres thought the 

 position of its spines and barbels, and the resemblance of its 

 mouth to that of Hypostoma, should rather arrange it with the 

 Siluridse. The specimen belonged to the Essex County Natural 

 History Society. 



Mr. Ayres also exhibited a specimen of Psolus, which, 

 he remarked, differed from P. Iccvigatus, described by him 

 at the last meeting of the Society, in its greater size and 

 more robust form, and in having the scales much more 

 closely set and more thickly granulated. The species is 

 either identical with P. phantapus, or very nearly allied to 

 it ; so nearly that without direct comparison it is scarcely 

 possible to show in what it differs. The specimen belonged 



