KI.I.IHKAV IIIATA "! 



I. >nt a pr.l 



Citrtnlnntu hulli Nettleroth. -p.. fntin t lie upper ln-.U of tin- llud-on river ^roup of 

 Kentucky. is shorter and thicker. an. I ha< more prominent Leaks and uinl>onal 

 rid 



Formation and locality. Thf typical fnrm upper part nf tin- mnl.i;.' third i.f tin- I 



i. .11 v Mi i.f Can iiMMOta. The Calroa variety was collected nmr Wykoff, 



III I 1 liilllr.- r 



CTRTODONTA. PARVA, n 



I'l.Al I \\\l\. 1 li.- ?4nd . 



This small species seems to be closely related to C. ajjinis 1'lrich and ('. lialli 

 Nettlenith. sp. In some respects it is intermediate between those species, ditlering 

 from the tii st iii its greater convexity, stronger umbonal ridge and larger anterior end, 

 these beiiiK point- m which the shell agrees rather closely with the latter. From both 

 it di tiers in the more abruptly rounded postero-basal margin and straighter ventral 

 outline. 



Adductor scars very faint, undetermined. The specimen being a cast of the 

 interior, the detail of the hingement could not be made out with certainty. 

 ^atest length, 9.5 mm.; greatest hight, 6.5 mm.: thickness, 4.5 mm. 



Formation and locality. Middle Galena, near Fountain, Minnesota. 



CYRTODONTA ROITLATA, n. sp. 

 PLA ; IIUB. -. 



Shell small, moderately ventricose, nearly erect, the outline uniformly rounded 

 iMilirirculur) except at the dorsal margin, which is straight behind the beaks and 

 somewhat insinuated in front of them; hight and length about as five is to six; 

 posterior extremity of hinge angular. Beaks small, incurved, scarcely prominent, 

 Mttiated about one-fourth of the length of the shell behind the most prominent point 

 on the anterior margin. Umbonal region full, but not excessively so; point of 

 greatest convexity a little above and in front of the center of the valves; postero 

 cardinal -lope gently concave, cau^injz this part of the shell to appear as slightly 

 alate. Surface marked with tim> concentric lines, with a few (those shown in the 

 illustrations) stronger th.m the rest. Shell and hinge plate thin; dentition undeter- 

 mined beyond this that it is essentially as called for by the genus. Muscular scars 

 unknown. 



I am not acquainted with any species of Cyrlndnnt'i. d>>criled heretofore, with 

 which this one mi^'ht le .-unfounded. ' y.fr>///>- 1'lrich. a much larger speciee, is 

 in outline somewhat like it. hut on comparison proves to have the beaks situated 

 farther forward and to be proportionally less ventricose. S i-ecies belonging 



