TRANSACTIONS OV THJJ SECTIONS. 99 



The first two groups have the arrangement of the parts of their steins analogous 

 to that which exists in the first year's growth of a dicotyledon. In both there is a, 

 parenchymatous medulla surrounded by a continuous vascular cylinder, which is 

 perforated in regular manner by meshes i'or the passage-out of the vascular elements 

 of the appendages. The stems of the third group have a structure analogous to 

 that which is found in the stems of monocotyledons ; for in both we have the vas- 

 cular bundles of the appendages existing in the parenchymatous axis, and passing 

 out independently of any closed cylinder. The permanent elements, however, of 

 the circumference of the stems of Pmronius are without any analogue in mono- 

 cotyledonous stems. 



. There seems, then, good reason for establishing two groups of ferns, vdth differ- 

 ences characteristic of their stems, comparable to those which distinguish the steins 

 of monocotyledons from those of dicotyledons. Cut the caution I have always in- 

 sisted on in dealing only with vegetative organs is specially required here ; for I 

 have discovered, I believe, the fruiting-fronds of one species of this group of plants. 

 With the Bath specimens of Stcmmatopteris insif/nis, Corda, as well as with those 

 found on the Continent, the fronds of Pecopteris arborescens are always associated. 

 It is the only fern found with some of the Bath specimens. It is also to be ob- 

 served that the bases of the stipes correspond with the size of the leaf-scars on the 

 stems. These facts are not absolutely sufficient for the correlation of the fronds 

 with the stem ; but they are the best evidence fin- this that we can expect in fossil 

 botany short of actual organic union. Now the fruit of Pecopteris arborescens is so 

 near to that of Cijathea, that I can find no characters whereby they canbe separated. 

 Our classification based on the stems must of course yield to that derived from the 

 organs of fructification ; and our group of ferns instead of being made into a new 

 order, as it would be by some who publish on fossil botany, must be grouped with 

 a tribe of recent Poh/pocliace<s. 



It may seem that this is a forced and arbitrary gi'ouping together of plants that 

 in some important characters so remarkably differ ; and so it is, undoubtedly, to 

 those who with rash confidence generalize on tlie systematic position of plants from 

 stem-structure alone. But what can such objectors say to the practice of placing 

 in close proximity plants that are beyond question nearly related to each other in 

 ail essential characters, though some have caudiccs (Lasf.rea Sec), while others pos- 

 sess rhizomes (Pteris &c.) ; yet these two forms of steins are more widely separated 

 from each other than the stems of the extinct palceozoic group are from those of the 

 recent forms. 



On thejiresent state of onr Jinowledge in connexion ivUli the Bracliiopoda*. 

 By Thomas Davidson, F.R.S., F.G.S. 



In this brief notice Mr. Davidson referred to the attempts recently made to re- 

 move the Brachiopoda from the Mollusca and place them with the Anuelides, 

 Mr. Davidson still adheres to the view entertained by the larger number of zoolo- 

 gists, that the Ih-achiopoda form part of a class {MoUuscoidea) independent of, but 

 related to the Mollusca ; he remarks, likewise, that some characters of the Brachio- 

 poda are certainly very puzzling ; but it must be borne in mind that any inverte- 

 brate group may be " annelidized " by overrating certain points of its affinities. 



Mr. Davidson next alludes to the fact that the Brachiopoda are amongst the earliest 

 Imown forms of animal life, and occupy, after the Trilobites, the most prominent 

 place in the animalization of the globe. He then alludes to the many important re- 

 searches made since 1853 in connexion with the anatomy of the animal, a:i well as 

 with reference to the animal in life, especially by Messrs. Barrett, Lacaze-Duthiers, 

 Jeffreys, Forbes, Dall, and others, and which would tend to show that the animal 

 cannot extend its arms beyond the shell, is rather sluggish, and apparently insensiljle 

 to light. In 1853 he laid before the public a review of what had been done 

 by others as well as himself in relation to the classification of the Brachiopoda, 

 proposing at the time to divide the class into about forty-five genera; but 

 since then some sixty-nine additional genera had been proposed by twenty-four 



* Trintcd in cx/enso in the ' Brighton Daily News ' for August 20, 1872. 



