52 PROCEEDINGS OF THE NATIONAL MUSEUM vol.68 



in identifying the specimens figured on plate 1 with Hinde's species. 

 Our specimens, of which there are many and all surprisingly alike, 

 differ from Hinde's description and figure in that the carina, 

 although becoming very thin, is nevertheless distinguishable quite 

 to the edge of the plate. This feature is even better indicated on 

 the lower side. The arrangement of the surface tuberculation indi- 

 cates a rather decided radial arrangement of the rows of tubercles, 

 which in certain lights appear like simple raised lines. The carina 

 of the branch to the lateral lobe leaves the main crest at approxi- 

 mately right angles. It is thin in its inner part, but the branch 

 thickens toward the margin of the plate. 



Occurrence. — Devonian (Rhinestreet) : Shaleton, N. Y. 



PUsiotypes.—Cixt. No. 11309, U.S.N.M. 



PANDERODELLA, new genus 



Platelike structures consisting mainly of a high but thin pecti- 

 nated crest with a broad basal expansion (plate proper) developed 

 on one side of crest only and extending its full length. 



This genus comprises a series of structures trending toward the 

 leaflike Polygnathus plates but differing in that the pectinated crest 

 is the major part of the structure and the basal expansion or plate 

 proper is developed only on one side. The crest is highest at one 

 end, presumably the posterior one. It differs again in that the lateral 

 area extends the full length of the crest. The cross section of the 

 plate and crest is therefore L-shaped. The basal expansion is smooth. 

 The denticles of the ci'est are joined, becoming free onlj- at their tips. 



Genotype. — Panderodella truncata^ new species. 



Range. — Upper Devonian and Early Mississippian. 



Although we provisionally assign this genus to the Polygnathidro, 

 the fact that several species show a protuberance near the middle 

 of the unflanged side, a feature common in many typical conodonts, 

 makes it possible that the genus does not represent a dermal plate. 



Polygnathus scitulus Hinde and P. solidus Hinde apparently be- 

 long to this genus. 



PANDERODELLA TRUNCATA, new species 



Plate 9, figs. 15-17 



Plate as a whole characterized by rectangular broader end taper- 

 ing slowly to a point of less than half the height at the other end 

 and by the rather narrow and not sharply bowed over basal flange 

 and small regular subequal denticles laterally in contact. 



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

 Tenn. 



C oty pes.— C?it. No. 11040, U.S.N.M. 



