DESCEIPTIOJSfS OF SPECIES. 351 



1892. Meekella striatocostata. Hall and Clarke, Pal. New York, vol. 8, pt. 1, p. 265, pi. 10, figs. 18-23; 

 pi. IIB, figs. 20-22. 

 Upper Coal Measures: Winterset, Iowa; Lawrence County, Kans. 

 1895. MeeTcella striatocostata. Keyes, Missouri Geol. Surv., vol. 5, p. 68, pi. 39, flgs. la-c. (Date of 

 imprint 1894. ) 

 Upper Coal Measures: Kansas City, Mo. 

 1900. Meekella striatocostata. Beede, Univ. Geol. Surv. Kansas, Eept., vol. 6, p. 65, pi. 12, figs. 9-9c. 

 Upper and Lower Coal Measures: Fort Scott, Olathe, Kansas City, Eudora, Lawrence, Lecomp- 

 ton, Topeka, Beaumont, Grand Summit, Kans. Widely distributed but moderately rare 

 throughout the Coal Measures and base of the Permian. Abundant near base of Permian. 



Shells referable to the genus Meekella have been collected at three localities, but 

 I am dissatisfied, I confess, with the specific disposition which their unfavorable 

 condition has led me to make of them. At Deadwood Gulch in the San Juan region 

 (station 3229), specimens are abundant but fragmentarj'. At the two other points they 

 are rare and also f I'agmentary. At the former occur specimens which can without 

 impropriety, so far as their imperfect condition permits judgment, be placed with 

 Cox's Meehdla striatlcostata. From this type there is deviation in several directions, 

 a very noticeable phase of which consists in a varying obsolescence of the longitudinal 

 plications, and accompanying it of a manifestation by the striae of a strong tendency 

 to grow straight and parallel, instead of being arranged in a somewhat pinnate manner 

 as in the typical variety. In some of these specimens, also, the striation is much finer 

 than in typical examples. 



At Silver Creek (station 2309), also in the San Juan, the only speeimen obtained 

 shows a form with high area whose surface lacks all but the faintest traces of plications 

 and is covered with fine, straight striae which are more or less regularly unequal. 



A still difi'erent type is found in a dorsal valve from Leadville (station 2254). 

 Here the striae are coarse when compared with the last, but, like them, are rigid and 

 l^arallel. Plications, provided they have not been obliterated by crushing, are almost 

 obsolete. Where the crest of each would probablj^ be situated, one of the strife is 

 exaggerated, the intermediate ones numbering six or eight. 



I judge that there are two species or varieties involved in this collection, or 

 possibly three, but the small amount and wretched condition of my material prevents 

 ascertaining their respective limits or their mutual relations. It was apparently for 

 a form similar to those with faint plications and straight, parallel stride that Swallow 

 proposed the name Orthisina shmnardiana, and this name, it seems to me, it would 

 be well to retain, at least in a varietal sense. 



Locality and horizo7i. — San Juan region (stations 2229, 2309?); middle portion 

 of the Hermosa formation. Leadville district (station 2254). 



