NO. 1908. NEW SILURIAN M0LLU8CA FROM MAINE— WILLIAMS. 391 



straight part of hinge Une about 14 mm. Two other specimens 

 reach a greatest diameter of 35 and 40 mm., respectively. 



The shell substance of tliis species is partially preserved in one 

 specimen and the form is well preserved in all specimens seen, show- 

 ing no evidence of crushing, thus differing from the other species of 

 the genus from the higher formation. 



Locality. — This species was found in an-isolated outcrop near the 

 end of Denbow Point, associated with brachiopods, trilobites, and 

 cephalopods, thus indicating that it lived in marine conditions. In 

 this respect E. denhowensis differs from all the other species of the 

 genus here reported, associated with which the only known marine 

 organisms are Lingulas and ostracods, signifying that their habitat 

 was littoral, shallow waters, possibly estuaruie. 



HoJotype and paratype. — Cat. No. 58449, U.S.N3I. 



CLIOPTERIA, new genus. 



A gibbous pterinoid shell, both valves highly arched with prom- 

 inent over-arching beaks; nearly equivalved, inequilateral. The 

 anterior slope of the right valve marked by one or two radiating, 

 rounded, cord-like ridges and the left valve by corresponding furrows. 

 The posterior slope smooth and more abrupt than the anterior side. 

 Anterior ear small, separated by a shallow sulcus from the main 

 body of shell. Posterior slope gradual and without distinct wing. 

 A high, flattened, triangular area under the beak in both valves. 

 Beaks of both valves overarching. In none of the specimens seen 

 is the dentition of the hinge exhibited. 



Note. — While this paper was being printed some specimens of Cliopteria unicosta 

 were discovered showing the mold of the hinge margin with distinct teeth. The fol- 

 lowing characters therefore may be added to the above definition of the genus, 

 viz: Two short lateral teeth near the posterior end and two near the anterior end 

 of the hinge of the right valve; one short strong lateral tooth at each end of the hinge 

 of the left valve. In both valves the margin of the hinge between the lateral teeth 

 is beset by sharply defined denticulations or small teeth. 



Type-species. — Cliopteria bicostata new species. 



OBSERVATIONS ON THE GENUS CLIOPTERIA. 



This genus is founded for some peculiar small pterinoid shells 

 which bear considerable resemblance to the Devonian species Avicula 

 dispar Sandberger as interpreted by Freeh, and called by him Kochia 

 (Loxopteria) dispar (Sandberger).* The name Kochia Freeh was 

 introduced to replace Roemeria Koch, which was preoccupied by 

 Edwards and Haime, the type of wliich is Roemeria capulifomiis 

 Koch, to which our specimens present small resemblances. Freeh 

 then created the subgenus Loxopteria as a subgenus of Kochia to 



> Die Devon Avicullden Dcutschlands, Abh. Gool. Speclalk. Preus., vol. 9, Ileft. 3, 1S91, p. 77, pi. 6, 

 Dg.4. 



