48 PROCEEDINGS OF THE NATIONAL MUSEUM vol. G8 



POLYGNATHUS CRASSULUS. new species 



Plate 8, figs. 8-10 



Lower (8) and top (10) views of the same specimen with figure 

 9, representing a three-quarters basal and edge view. The outline 

 and markings tend to be irregular although the lanceolate form is 

 maintained. The crest runs through on both surfaces although very 

 high in posterior part of upper side. Anterior half of upper sur- 

 face irregularly tuberculated and posterior half irregularly plicated. 

 LoAver surface with concentric lines and undulations. 



Occurrence. — Mississippian (Hardin sandstone) : Mount Pleasant, 

 Tenn. 



Holotype.—Q^X. No. 11001, U.S.N.M. 



ANCYRODELLA, new genus 



Similar to Polygnathus but the depressed lateral areas are drawn 

 out at the wider end so as to give the whole plate an anchor like 

 outline. 



Genotype. — Ancyrodella nodosa., new species. 



Range. — Upper Devonian and lower Mississippian. 



ANCYRODELLA NODOSA, new species 



Plate 1, figs. 10-13 



Plate anchor or somewhat harpoon shaped, essentially bilateral 

 in form with a central crest prolonged posteriorily into the free 

 shaft like extension, and rather narrow posteriorilj'^, w^idely diverg- 

 ing but finally incurving, flukelike lateral limbs. The median crest 

 and also the median lines of the flukes are made by a series of basally 

 connected strong nodes and a similar row of nodes form an elevated 

 edge around the whole fluke. 



Occui^ence. — Devonian (Rhinestreet) : Shaleton, N. Y. 



G oty pes.— Cfit. No. 11303, U.S.N.M. 



ANCYRODELLA HAMATA, new species 



Plate 7, fig. 7 



Readily distinguished from the genotype by lacking the row of 

 nodes on the lateral appendages. As in that species the shape simu- 

 lates the head of a harpoon. The shaft passes into a median crest 

 extending to the anterior extremity with the marginal portions 

 throughout, coarsely tuberculate. 



(9c<?w7V'en^6.— Mississippian (Hardin sandstone) : Mount Pleasant, 

 Tenn. 



Holotype.—Cni. No. 11011, U.S.N.M. 



