PROCEEDINGS 



OF THE 



Cambrttrgc ipljilasnpljtcal S0rieti|, 



Monday, Jan. 30, 1893. 

 Professor T. McK. Hughes, President, in the Chair. 

 The following Communications were made to the Society: 



(1) On a new Fern from the Goal Measures. By A. C. 

 Seward, M.A., St John's College. 



Abstract. 



The specimen described as a new species, Rachiopteris William- 

 soni, resembles in certain particulars the genus Myeloxylon, but 

 possesses distinctive characters not previously recognised in fossil 

 Fern petioles. Rachiopteris Williamsoni may be briefly described 

 as a petiole with scattered vascular bundles ; those near the 

 periphery appear to be rather collateral than concentric in struc- 

 ture, but the larger bundles have a more decided concentric 

 arrangement of the xylem and phloem. Each group of xylem 

 elements is surrounded by a ring of small secretory canals. The 

 hypoderm is like that of Myeloxylon, and gum (?) canals are 

 abundantly distributed in the ground tissue. 



(2) On the Structure and Functions of the Alimentary Canal 

 of Daphnia. By W. B. Hardy, M.A., Caius College, and 

 W. Mc DouGALL, St John's College. 



[Received March 28, 1893.] 



So far as we know none of the workers who have investigated 

 the gut of the Crustacea have described the existence in the 

 case of the lowest members of that group of a differentiation of 

 regions corresponding to the processes of digestion, of absorption, 

 and of elaboration of the feeces. As is well known, the gut of 

 the lower Crustacea differs in a very striking way from that 



VOL. VIII. PT. II. 4 



