88 ZAMITES. 



connect the name of Mr. Carruthers with the present species of 

 cycadean frond, as a slight recognition of his valuable contributions 

 to our knowledge of the fossil Cycadacea. 



Some of the large detached pinnse figured by Fontaine as 

 examples of his new species Zamites tenuinervis, agree fairly closely 

 with those of the present form, but in the Potomac plant the 

 venation appears to be coarser, and the bases of the segments 

 usually "abruptly subcordate " ; in the pinna shown in Fontaine's 

 pi. Ixxvi. fig. 7 the base seems much more like that in the English 

 specimen. The paucity and imperfect character of the Potomac 

 material, and the differences already alluded to, hardly warrant 

 the adoption of Fontaine's name for the English forms. There is a 

 close resemblance between the present specimens and some of those 

 referred to Z. Suchianus, e.g. V. 2123, but in the latter species 

 the longer and more gradually tapering pinnae are sufficiently 

 characteristic to distinguish the two forms. Among recent cycads, 

 Enceplialartos longifolim, Lehrn., is one of those which resemble 

 very closely in habit the fronds of Z. Carruthersi. As examples 

 of other fossil fronds to be compared with this species, Zamites 

 affinis, Schenk, 1 and Palaozamia recta, Tate, 2 may be mentioned. 



V. 2123d. PI. VI. Fig. 4. 



In this specimen the manner of attachment of the pinnae is 

 clearly shown ; the line of separation being particularly distinct 

 at the base of the middle pinna of the portion of frond represented 

 in Fig. 4, PI. VI. Rachis at least 1 cm. broad, and marked with 

 fine longitudinal lines. Venation very distinct, as in V. 2123c. 

 Only a portion of the specimen shown in the figure ; rachis 

 21 cm. long. Ecclesbourne. Rufford Coll. 



V. 21230. PI. VI. Figs. 2 and 3. 



The pinnae are very like those with blunt apices which have 

 been included in Z. Buchianus (e.g. V. 2227), but in the present 

 specimen the base and manner of attachment of the pinnas con- 

 stitute the special features. The form of base clearly seen in 

 Fig. 3, and the blunt apex with the slightly divergent veins in 

 Fig. 2. Rachis in this specimen 13cm. in length, with portions 

 of nine pinna? on one side. Ecclesbourne. Rufford Coll. 



1 Pakeontographica, vol. xix. pi. iii. fig. 6. 



2 Tate (A.), Quart. Journ. Geol. Soc. vol. xxiii. pi. v. 



