no. 1600. ON THE REVISION OF PTERINEA GOLDFUSS—WILLIAMS. 87 
genus. For this group the name Yolmannella is proposed in honor 
of Dr. Otto Follmann, who has rendered a lasting service to Paleonto- 
logy in his work Uber Devonischen Aviculaceen. 
FOLLMANNELLA, new genus. 
Type.—Pterinea mainensis Clarke. 
Diagnosis.—Pterinoid shells with low convex left valve, and flat or 
concave (resupinate) right valve; hinge line produced, wider than 
body of shell in young, but much shorter than greatest width of 
mature shells. Body of shell oblique, in young shells inclining back- 
ward 25 to 40 degrees from the hinge line in a straight line; in 
mature shells (50 mm. long and over) the lower part of the body 
curves backward forming a broad posterior extension, the extreme 
margin of which reaches considerably beyond the posterior end of 
the wing. ‘This is a characteristic expression of full grown shells of 
this genus. 
Radial sculpture on outer surface of nondecorticated left valves 
usually fine and numerous as in 7’o/maia; similar sculpture on body 
of right valves of type species but less distinct than on left valves. 
Cardinal teeth, posterior lateral teeth, muscular scars, and resupina- 
tion of right valve as in Pterinea (sensu stricto), Tolmaia, and Cor- 
nellites. Teeth not as in I/icropteria. 
The type species of this genus is from the Eodevonian of Moose- 
head Lake region in Somerset County, Maine. 
A. NEW PTERINOID GENUS ACTINOPTERELLA RESEMBLING EXTER- 
NALLY THH AVICULOID GENUS ACTINOPTERIA. 
Among the Pterinoid shells of Maine, specimens which at first were 
referred to Actinoptera appear to be distinctly Pterinoid, as shown 
by their teeth and muscular scars, but differ generically from the 
Pterineas (see Tolmaia) by their strongly convex mght valves. 
For this group of shells the generic name Actinopterella is pro- 
posed. 
ACGCTINOPTERELLA, new genus. 
Type.—Pterinea radialis Clarke, part. 
Diagnosis.—Oblique pterinoid shells with posterior wing and an- 
terior ear both well developed; both valves strongly convex, left 
valve ventricose, with narrow oblique body; right valve generally less 
convex than left but convex from beak to ventral margin, not be- 
coming resupinate. Umbones protruding slightly beyond the hinge 
line. Ligamental area well developed, striated; cardinal teeth pres- 
ent, three or four in number; lateral teeth (or tooth) well developed 
and close to hgamental area. A small, deep, anterior muscular scar 
