GIRTY, 'NEW CARBONIFEROUS FOSSILS 229 



ill the outline. Tlie posterior one is bounded by a fold which in fact appears 

 to be double. 



Surface marked by very numerous, fine, sharply elevated, radiating lirse, 

 which decrease in size and definition toward the sides and are not developed 

 at all on the posterior wing. The intervening strife are about equal in size 

 and shape to the llrse. There are also many closely arranged, more or less 

 irregular and unequal concentric striae, finer than the radiating lirse and 

 subordinate to them. Occasional varices of growth sometimes defiect the 

 lirfe and give them a wavy appearance. 



Aviculipecten morrow^ensis sp. nov. 



Shell small, a length of 11 mm. being about the maximum observed. Length 

 and breadth nearly equal, or the breadth a little in excess. Hinge long but 

 considerably shorter than the width below. Axis slightly inclined backward, 

 with a greater development of the shell behind than before. Wings broad, 

 undefined either' by being abruptly depressed or by a sinus in the outline 

 which is nearly straight and slightly oblique on the anterior side, slightly 

 concave and strongly oblique on the posterior side. The lower part of the 

 outline is regularly rounded. The anterior wing is larger than the posterior. 

 The convexity is low and the umbones small and inconspicuous. 



The surface is crossed by numerous exceedingly fine lirse which are scarcely 

 visible without a lens. These are sharply elevated, rounded, with interspaces 

 of about their own width, and they are in some cases slightly wavy. They 

 bifurcate occasionally and thus tend to form groups or fascicles which in one 

 specimen are visible to the naked eye as very obscure, regularly arranged 

 costse. of which there appear to be six or seven. The radii are also more or 

 less alternating. They are crossed in some cases by regular, fine, sublamel- 

 lose, concentric lirse, which are differently arranged in different examples. In 

 one specimen, they are much farther apart than the radiating lirse ; in another, 

 only slightly farther apart. In most examples, they do not appear at all. the 

 concentric markings consisting of fine, incremental strise, of which a few at 

 irregular and distant intervals are stronger than the rest. On the wings, the 

 radii become very obscure, while the concentric striae are intensified and con- 

 spicuous. In some specimens, the radii are sharp and strong ; in others, pos- 

 sibly by exfoliation, they are more obscure. It may be owing to the same 

 causes that the lamellose concentric lirse appear to be absent. 



Aviculipecten inspeciosus sp. nov. 



Shell small, a length of Ifi mm. being abovit the maximum observed ; length 

 and breadth nearly equal. The hinge is rather short, about one half as long 

 as the greatest width. The axis seems to be curved so that the greater devel- 

 opment of the shell is on the anterior side. The po.sterior wing is small and 

 not defined by a sinus in the outline. The latter contracts strongly as it ap- 

 proaches the hinge, near which, however, it appears to be somewhat straight- 

 ened on the posterior side. On the anterior side, it rounds strongly inward 

 to the base of the anterior wing, where it changes direction, becoming nearly 

 straight and sloping gently Inward (from below) so as to meet the cardinal 

 line at a slightly obtuse angle. The convexity is rather high. The posterior 



