DESCRIPTION OF SPECIES. 45 



usually argillaceous, flaggy sandstones, overlying the lower coal seam at 

 Clover Hill, Carbon Hill, Midlothian, and at Manakin in the beds pierced 

 by the Aspinwall Shaft. 



Asterocarpus Virginiensis, var. obtusiloba. 

 Plate XXI, Figs. 3,4; Plate XXIV, Figs. 3-5; Plate XXV, Fig. 1. 

 Frond tripinnatifid, perhaps arborescent. Fertile form not seen. Steinle pinnae 

 of ultimate order linear-lanceolate, sometimes very long, with stout, rigid rachises, 

 alternate, going off at an angle of about 45°, and slightly curved upwards. Lobes, or 

 united pinnides, alternate, united by one-third their length, and more, very thick and 

 coriaceous, broadly oval, with very blunt and rounded terminations, very slightly 

 curved forwards. Nerves very distinct, sharply denned, usually strong and promi- 

 nent. Midrib inserted below the middle of the pinnule or lobe, stout at base, dis- 

 solved towards the summit into branches. Lateral nerves somewhat various. In all 

 cases some depart from the principal rachis and curve at first outwards and towards 

 their extremities, often upwards, meeting but not uniting with the similarly placed 

 lateral nerves of the adjoining pinnules. Lateral nerves from the midrib going off 

 obliquely, and forked from the base either once or twice, those forking twice being in 

 the lower part of the pinnules ; usually strong, but sometimes slender and so much 

 crowded that the long, slender branches are so closely approximated as to appear 

 single. 



This plant has a constant facies of its own, and being found only at 

 Clover Hill, it might perhaps with propriety be separated as a distinct 

 species. As, however, the general character is similar to that of Asterocar- 

 pus Virginiensis, and as this plant is quite variable, I have thought it best 

 to unite the two. The points of difference, however, are quite numerous. 

 The ultimate pinna? are not opposite, or subopposite, as in A. Virginiensis, 

 the lobes or united pinnules are broader, blunter, and united more uniformly 

 to about half-way their length, and no single or simple large pinnules are 

 ever seen. These simple large pinnules are the most common forms of the 

 normal A. Virginiensis. The variety now in question appears only at Clover 

 Hill, where it occurs with the normal A. Virginiensis, from which it is easily 

 distinguished. The form represented in Plate XXV, Fig. 1, if seen alone, 

 would be entitled to rank as a distinct species, but when it is taken in con- 

 nection with the forms given in Plate XXIV, Figs. 3, 4, the separation from 

 the normal A. Virginiensis is not easily made. The form given in Plate 

 XXV, Fig. 1, presents some peculiarities. The nerves here are very much 

 crowded, slender, and sharply defined. The lateral nerves fork at their 



