Q98 MR. W. CARRUTHERS ON FOSSIL CYCADEAN STEMS 



aro small ovoid bodies, and are composed of two envelopes enclosing the albumen and 

 embryo. The outer envelope, or testa, consists of a thin layer of delicate elongated cells ; 

 the inner is composed of a single series of oblong cells, arranged with the longest diameter 

 at ri lit angles to the walls (Plate LIX. figs. 6, 7, 8), and indurated by a considerable 



— — 



amount of secondary deposits. In the preparation (fig. 7), the seed is cut through at the 



halaza, and the opening (through both envelopes), by which the vascular bundle entered 



is -.'en. On passing within the tegmen, the bundle expanded, forming a small cushion 



below tin; nucleus (fig. 7). The two coverings were produced upwards into a tubular 



exostome or styliform process, which, passing through the neck of the pit in which the 

 seed is buried, was spread out like a stigma on the upper surface of the pericarp (fig. 6). 

 The aspect of the whole Bruit would closely resemble a reflexed receptacle of Tambourissa 

 Covered with innumerable stigmatic processes from the fruits buried in it, as figured by 

 Baillon, 'Monogr. des Mouimiacees,' p. 311. Enclosed by these envelopes is the nucleus, 

 with it- membranous covering, and abundant albumen. The subrectangular cells of the 

 d humeri are obvious in several specimens (fig. 9) ; but I have not hitherto detected the 

 embryo. Its position may, perhaps, be indicated by a cavity which exists in some spe- 

 eimens in the upper part of the seed, and which was probably produced by the early decay 



md disappearance of the embryo. In some specimens an apparently confused arrange- 

 ment of cellular tissue occupies this cavity (fig. 9) ; but I cannot detect in it the form of 

 the embryo, though there can be no doubt that it really represents it. The albumen was 

 >olid behind the embryo, but was divided from top to bottom down its centre, in front of 



the embryo. 



In »m paring the structure of this plant with the inflorescence of the recent Cycadece, 

 the points of difference are more obvious than those in which they agree. The most im- 

 portant correspondence is to be found in the structure of the seed and its envelopes. The 

 fossil is truly uymnospermous, the pollen having access to the embryo-sac through the 

 tubular openings in the covering of the seed, and not through a style developed from an 

 inyesting carpellary organ. The most remarkable difference is to be found in the com- 

 pound Bruit of the fossil. In the recent members of the order, the fruit, whether borne 

 on slightly modified leaves, as in Cycas, or on the peltate or imbricated scales of a cone, 

 as in the other genera, is always produced on foliar organs. In the fossil, on the other 

 hand, it is borne at the end of the axis. Iu this respect, however, it agrees with Taxus, 

 Kept that it possesses innumerable seeds; it must be considered to hold the same 



I latum to the other Cycadece that Taxtts, with its succulent, cup-shaped pericarp, doe. 

 i the eone-bearing Cotuferce. 



Bene k n i tes Saxbyas is, Carr. (Tab. LVII.) 



l .1. 



1851 



( >,cadit Sutbymm, a. Br. Proc. Linn. Soc. no. xlvi. p. 130 

 ( icadeoulea Saxbyvna, Morris, Cat. Brit. Poss. p. 7. 



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