ON STRUCTURE ETC. OF NAIAS GRAMINEA^ VAR. DELILEI. 29 



INDEX TO THE FIGURES. 

 Plate I. 

 Fig. I. Slab of Yoredale rock, with tracks of Chrossocarda tuberculata, Will. 

 Half the nat. size. 



2. Diagrammatic representation of a portion of one of the above tracks. 



3. A second fragment, with two tracks of somewhat more strongly 



defined contour than those of fig. i. Nat. size. 



4. Track of Protichnites Davisi, Will. Two fifths of the natural size. 



Plates II. & III. 

 5-13. Casts of a series of drainage-lines from the coast of North Wales 

 at Llanfairfechan. 



Plate III'. 

 14, 15. Two similar easts from the coast north of Barmouth. 

 These figures are all copied by an autotype process from photographs, 

 kindly taken for the purpose of illustrating this memoir, by Alfred 

 Brothers, Esq., F.R.A.S., of Manchester. 



IV. O71 the Structure, the Occurrence in Lancashire, and 

 the probable Source, of Naias graminea^ Delile, 

 var, Delilei, Magnus. By Charles Bailey, F.L.S. 



Eead April 29th, 1884. 



(Plates IY.-VII.) 



Page 



I. Introduction 29 



II. The Genus and its Divi- 

 sions 31 



III. Synonymy of the Plant. . . 32 



IV. The Stem 34 



v. The Leaves 36 



VI. The Leaf-spines 37 



VII. The Leaf -sheath 40 



VIII. Leaf-structure 45 



IX. The Inflorescence 47 



X. The Pistilliferous Flower 50 



XL The Antheriferous Flower 52 



Page 



XIL ThePoUen 55 



XIII. Fertilization 57 



XIV. The Fruit 58 



XV. The Roots 62 



XVI. The Lancashire Locality 63 

 XVII. Geographical Distri- 

 bution 66 



XVIII. Its probable Source ... 67 

 XIX. A Histological Peculi- 

 arity 69 



XX. Explanation of the 



Figures 72 



I. Introduction. 

 Naias qraminea, Del. (Plate IV. fig. i), aud Chara Braunii, 

 Gmel., were first reported as occurring in a natural state 



