506 bulletin: museuim of comparative zoology. 



Craniidae 



Crania laelia Hall, 



Crania laelia Hall, Descrip. Crinoidea etc., 1866, p. 131. 24th Rept. N. Y. 

 State cab. nat. hist., 1872, p. 220, pi. 7, fig. 16. Miller, Cine, quart, 

 journ. sci., 1875, 2, p. 12. Hall and Whitfield, Pal. Ohio, 1875, 2, p. 75, 

 pi. 1, fig. 16. HaU and Clarke, Pal. N. Y., 1892, 8, pt. 1, pi. 41, fig. 1. 

 Grabau and Shimer, N. A. index fossils, 1907, 1, p. 297, fig. 242. Cum- 

 ings, 32d Ann. rept. Dept. geol. nat. res. Indiana, 1908, p. 897, p. 33, 

 fig. 2. 



Shell small, inequivalve, oval in outline, with width greater than 

 length. Dorsal valve highly convex; beak elevated, pointed, situ- 

 ated nearly in the middle of the shell. 



Surface marked by concentric lines of growth as well as radial 

 striations. The latter vary considerably in number and strength. 



This shell is quite common in the Maquoketa at Clermont, Iowa, 

 and is usually found attached to an orthid or Rafinesquina. In no 

 case was the Crania marked like the surface of the host. 



Locality: — Mays\ille and Richmond; Cincinnati, Ohio, alid many 

 localities in Ohio, Indiana, Kentucky, Tennessee, etc., Lower INIaquo- 

 keta at Clermont, Iowa. 



Orthid AE, 



The most recent faunal lists have not adequately suggested the 

 variety of Orthidae to be found in the Maquoketa. Until quite 

 recently Plcdorthis (AvsiincUa) whitfieldi (N. H. Winchell) was the 

 only member of this common Palaeozoic family definitel}^ identified 

 from the various outcrops in Iowa, Illinois, Wisconsin, and Minnesota. 



Plectorthis (Austinella) kankakensis (McChesney). 



Orthis kankakensis McChesney, New Pal. fossils, 1861, p. 77. Trans. Chicago 



acad. sci., 1868, 1, p. 29, pi. 9, fig. 3. 

 Plectorthis kankake7i.sis Hall and Clarke, Pal. N. Y., 1892, 8, pt. 1, p. 221, pi. 5, 



fig. 24, 25. 

 Austinella kankakensis Foerste, BuU. sci. lab. Denison univ., 1909, 14, p. 224. 



The difference between P. kankakensis and P. tvhitfieldi is mentioned 

 in the discussion of the latter species. Both occur plentifully at 



