334 Mr Caldwell, On certain points [Mar. 12, 



the winter, the other bulbs had begun to grow before I was able to 

 examine them, and this may account for the absence of granules in 

 them, since the granules in the Narcissus bulb disappear soon after 

 the bulb has commenced to grow. 



March 12, 1883. 

 Mr Glaisher, President, in the Chair. 



Mr M. C. Potter, B.A., St Peter's College, was balloted for and 

 duly elected a Fellow of the Society. 



The following communications were made to the Society : 



(1) On certain points in the anatomy of Brackiopods. By 

 W. H. Caldwell, B.A. 



The knowledge of the structure and life history of the genus 

 Phoronis led me to put forward a new interpretation of the 

 body plan of Brachiopoda \ To test this I have examined species 

 of the following genus, viz. Lingula, Discina, and Crania among 

 Ecardines, and Argiope, Megeilea and Bhynconella among Testi- 

 cardines. In the present note I propose to trace some of the 

 modifications in structure occurring in these forms. I shall confine 

 myself to (i) the nervous system, (ii) the body cavity and mesen- 

 teries. 



Nervous system. 



The body wall of all Brachiopoda has a basement membrane 

 lying immediately below the ectoderm. 



The fact that this lamella passes into the septum dividing the 

 body cavity of the prseoral lobe from that of the trunk, suggests a 

 mesoblastic origin. In all the Brachiopoda I have examined,, the 

 central nervous system lies outside this basement membrane. 



Dr Van Bemelen has recently described 2 the central nervous 

 system as partly imbedded in this basement membrane. The 

 forms he studied were Terebratula vitius and Waldheimia Cranium. 



In both these species, as well as in Lingula Disima and 

 Rhynconella, very definite nervous tracts are present. The ecto- 

 derm over the greater part of the body has only a few kinds 

 of cells. In these forms there is a complete circumcesophageal 

 nerve ring, and various nerves passing off from this. These 

 peripheral nerves have however no constant position in the 

 different genera. In the smaller species I have failed to trace the 

 supracesophageal part of the ring round the mouth. But in 



1 Proc. Roy. Soc. Dec. 1882. - Jenaische-Zeit. Dec. 18*2. 



