CARBONIFEROUS AOB. 21 



Length of a Urge in.lmdual, O.:il inch ; breadth, 0.36 inch; conrexity, 0.23 inch. Longth of a young shell, 

 .2T iuoh; breadth. O.l inch; courexity, 0.15 inch. 



a b e 



d 



Spirtfrr (Mnrlinia) plamo-rnnvtrui. 



a. Side riew of medium iiied specimen, i. Ventral view of same, e. Donal rlw of tame. d. Donal riew ot a 

 larger transverse specimen, showing the area and foramen, t. Hinge and internal view of a separated ventral. 



This little shell seems to agree exactly with the species described by Dr. 

 Shuinanl under the name .V////-/A / />/rr/<o-<-o/r.r, and by Mr. McChesney, as 

 iji iinniilii, excepting that none of the (twenty or thirty) specimens we have seen 

 show the taint medial depression or sinus in the ventral or larger valve, mentioned 

 by these gentlemen. As some of them, however, show a very slight flattening of 

 the inidille of this valve, it is probable other individuals may possess an obscure 

 narrow sinus. It is worthy of note that the descriptions given by these gentlemen 

 agree quite as well with the European S. Urei, and we arc strongly inclined to the 

 opinion that the form described by them, as well as that now before us, really belongs 

 to that well known species. Still, as our specimens nearly all differ from all the 

 figures of that species we have seen, in having the smaller valve, especially in adult 

 examples, a little concave, and the ventral valve destitute of a mesial sinus, while 

 they attain a much larger size, we have concluded to place them provisionally under 

 Dr. Shnmard's name i>l<mtnxnrexuA.* 



As the closely allied Spirifer (JfiwfMMa) itmlxmatus (= Orthis nmbonata, Conr.), 

 I'm- \\ liich the new generic name Aniloccelia has been proposed, is described as having 

 a " fihro-pnnctate" structure, we examined the structure of the species under con- 

 sideration \ er\ carefully, by transmitted light under a high magnifying power, to see 

 if we could detect the presence of punctures ; but after repeated trials we failed to ob- 

 serve any traces of them, though we saw distinctly the usual fibro-prismatic structure. 



LucnUh/ iiinl jH>x!iii>n. Manhattan, on Kansas River; Upper Mill Creek, and 

 at \arious other localities in Eastern Kansas. Coal Measures. (Type of descrip- 

 tion and figures, 996, a, 6, e.) 







FAMILY PRODUCTION. 



Shell free or attached by the substance of the beak, concavo-convex ; 

 valves articulated by teeth and sockets, or retained in place by the action 

 of imiM-Irs only; hinge with or without a cardinal area; oral append;! 

 without calcified supports, and probably ileshy and spiral; surface more 

 or Ic^s spinous; substance fibro-punctate. 



Animal unknown. 



1 Since this was in type we linvr received a letter from Dr. Shnmard, to whom we had sent the cuts 

 of this species, in which he says he has uo doubt of its identity with his jS'. jilano-convexut. 



