EXPLANATION OF THE PLATES AND WOOD-CUTS. 



Stem ? internal structure unknown, replaced by sandstone. 



External structure ; stem flattened, sinuous, with bifarious ascending protube- 

 rances, somewhat conical and obliquely truncated, the apex of each formino- a 

 nearly circular scar, with a depressed lateral cavity ; the side of each scar marked 

 by a transverse depression ; surface of the stem thickly covered with small oblong 

 or irregular shaped projecting cicatrices, disposed in a quincunxial order, which 

 become elongated and larger as they approach the protuberances. 

 In the older portions the cicatrices are less prominent. 



The resemblance of this specimen in some characters to Halonia has induced 

 us to place it in that genus ; although it differs in the smaller number of protube- 

 rances which are found on the surface, the bifarious position of which will at once 

 distinguish it from all the other species. 

 Fig. 2. Bechera charccfonnis, (Sternberg, t. 55, f 3, 5.) B. delicatula ? Sternb. t. 

 49. f. 2. Stem striated, jointed, verticillately branched, branches dichotomously 

 whorled, leaves subulate. 



This specimen is the same as Sternberg's figure, t. 55, and his B. delicatula ap- 

 pears to be only an imperfect variety of the same species. 

 Fig. o. Stigmariajicoides. The portion of stem of which the figure is a transverse 

 section, is in more perfect preservation than the specimens of Stigmaria usually 

 are found ; it is of a nearly cylindrical form, about 4i inches diameter, the exter- 

 nal surface exhibiting the usual markings of this curious plant ; the internal part, 

 with the exception of a vascular cylinder (also mineralized), being replaced by 

 clay ironstone. 



In the Fossil Flora, t. 31 — SQ, are figures and descriptions of Stigmariajicoides, 

 and at t. 156 is shown the structure of the same ; and although we cannot add 

 much, new information to that previously given by Prof. Lindley, it has been 

 thought advisable to have another section represented with a view of showing what 

 has hitherto not been well illustrated in the published figures of its structure. 

 The internal cylinder in the specimen (fig. 3.) is eccentric, and consists of wedge- 

 like portions of vascular tissue, the rounded origin of which, internally, is well- 

 defined ; these wedges are generally of equal or nearly equal size, but they occa- 

 sionally become confluent by the joining of two or more of them together. The 

 form of the space necessarily left, or interstices between the sections where these 

 are distinct, varies a little, in some cases being of nearly equal breadth through- 

 out, and in others becoming narrower outwards and appearing to terminate or 

 contract about the middle of the vascular tissue, beyond which they again fre- 

 quently widen outwards : these spaces often contain portions of oblique and 

 smaller vascular cords, appai'ently arising at diffei-ent depths in the vertical 

 cylinder ; the origin and connexion of which with the cylinder is shown in the 

 oblique section, where a single series of vessels is seen passing from it surrounded 

 by tissue of smaller diameter. PI. XXXVIII. fig. 3 a. 



In no specimen yet examined has the course of the oblique cords been abso- 

 lutely ascertained, but there can scarcely be any doubt, as suggested by Mr. Brown 

 (to whom we are also indebted for the above observations,) that these vessels after 



3 



