Marylaxd Geological Survey 565 



top of niouiiUun, aliuii'liuit ; Williams linad, on Polish [Mountain, 2042. 

 Parkhead Mejiber. Allegany Grove, 8~>n ? Williams Road, on Polish 

 ^loimtain, l(i(ii» abundant; Town Creek, IHG;] ; 2 miles west of Pa\vj)a\v, 

 1794. 



Collection. — Maryland Geological Survey. 



PliODUCTELLA LACHRYilOSA VAK. MAKYLAXDICA n. var. 



Plate LI, Figs. 4-9 



Drsrripfioii. — Quite as abundant locally as the preceding species is a 

 much and persistently smaller shell, with more sparsely eehinate surface. 

 There is no material difference between these and P. lachrymosa in the 

 proportions or internal structure of the valves, hut the exterior distinction 

 is marked, the surface heing sometimes almost devoid of spines and 

 apparently irregularly tubercled, hut generally the elongate spine-bases 

 are well apart over the pallial region ; on the cardinal slopes they become 

 erect and are somewhat mere abundant. This shell is readily dis- 

 tinguished by these features and it is clearly allied to P. larhri/inosa. 



Indixiduals occuning in the sction on ^\'illianls Itoad on Polish 

 Mountain are larger than those figured and the umbo is more inflated, in 

 which respect they approach the ncu'inal f(inu more closely. 



Length 13 mm.; width I'i mm. 



Ornirrencr. — -Tenxings Foiaivnox. ('iiicMrxG ^lE.Mm:i;. Williams 

 L'oad, Polish [Mountain. 1907, ^O-.M abundant; National Road, Polish 

 Mountain, abundant in b'ccky arenaceous shales; along Sideling Hill 

 Creek on Pennsylvania-Maryland state line, on top of hill. 



Collection. — [Maryland Geological Survey. 



Productella LAciiRYiiosA var. 



Plate LI, Figs. 10-12 



Drsrrijjtioii. — This variety differs from tlie typical foi'm of P. lacJirij- 

 uiosfi in its closer and more slender spines in which respect it approaches 

 P. six'ciosa. The umbo is larger, however, than in that species. It sug- 

 gests /'. hirsnld but does not show the concentric striae of that species. 



