FROM THE SECONDARY ROCKS OF BRITAIN. t 



present a rhomboid form, the horizontal diameter of which is bat little more than 

 the perpendicular. 



All the specimens of this fossil are found in the iron and green sands of Potion. Bed- 

 fordshire (Lower Greensand), in a sand-pit just outside the town of Leighton-Bu up U 

 the north-east. They are converted into a rich brown hematite. The ftgui . specimen 

 in the Museum of the Royal Agricultural College, Cirencester. I haw received speci- 

 mens from Mr. Yates, Prof. Morris, and Prof. Rupert Jones, which are now deposited in 

 the British Museum. 



In associating the name of Prof. Morris with this species, I desire to record m\ sem 

 of the great value of his critical observations on the species • >(" British i *sil Cyc<«l, , 

 and to acknowledge the debt I owe him for his numerous important verbal communica- 

 tions on the subject of this paper, and his information regarding memoirs in little-known 

 periodicals which would otherwise have escaped my observation. 



Y. gracilis, sp. nov. (Tab. LV. fig. 2.) 



Stem cylindrical, very slender, covered with the permanent has-softhe p :i<J<s, whicn 



are imbricated, subrhomboidal, and terminated by a lozenge-shaped cicatrix 



From the Lias of Lyme Regis. [British Museum.] 



The only specimen yet discovered of this fossil is somewhat flattened, and remains half 

 buried in its original matrix, so that it cannot be examined completely. No indicat ii m of 

 the internal structure of the stem remains; but the form and arrangement of the persisted 

 petioles is sufficient to determine its nature. The scar of an axillary organ, peri 1 1 >s (fi • m 

 its small size) the peduncle of a cone, is seen on the upper part of the stem. A 1< - perfod 

 indication of what may have been a forking of the stem is seen towards the base of th 

 specimen. 



Y. crass a, sp. nov. (Tab. LV. fig. 7.) 



Stem short, subcylindrical, covered with the persistent imbricated base, of the I 



which are transversely subovoid or imperfectly lozenge-shaped 



The ph\ 



represented by the fraction 



M 



[Dunrobin-' -tic Museum. 



The single fragment of this species which I have seen is imperfect bu it pwento 

 characters sufficiently distinct to warrant its being named and tombed. I. is ■ «*UI 

 the stem in white sandstone. No traces of the different parts of tin, stem are .hown 

 except the short thick imbricated bases of the petioles. 



Y. Joassiana, sp. nov. (Tab. LV. fig. 8 et 9.) 



Stem cylindrical, slender, branching ffichotomouslv, ^J**^, -^Z 



which are snbrhomboidal or lozenge-shaped, and sl.ghth _imbncai, d . 



represented by the fraction 

 pted longitudinal 



*- The cast of the woody axi I is marked wit hit* 



13' 



g.^^x.^ 



the Coral Has of 



M. 



[Dunrobin-Castle Museum.] 



