NO. 1395. CAMBRIAN BRACEIOPODA—WALCOTT. 319 



DICELLOMUS, species undetermined. 



A single specimen of a ^•^MltnlI valve verv nuich like that of 7>i<rl- 

 loinu.s appalaclud occurs with material from the J\ir<i<J<),i'lde>< forcli- 

 iHUiwri zone at Andrarum. A series of specimens would probably 

 prove that it is the representative of an undescribed species. 



Formati07h and locality. — Middle Cambrian. Andrarum, Sweden. 



CURTICIA, new genus. 



The description of the type species, Cnrtlcla elegatdvla, includes all 

 that is known of this genus. 



The generic name is given in recognition of the excellent work of 

 Dr. Cooper Curtice, of Moravia, New York, ])oth as a field collector 

 and laboratory assistant for se^'eral years. 



CURTICIA ELEGANTULA, new species. 



General form, subcircular, biconvex. Surface of exterior of shell 

 marked by fine concentric, slightly undulating stritB, and lines and 

 varices of grow^th. When the thin, exterior layer is exfoliated, the 

 inner lavers are ornamented bj' numerous tine, radiating lines, very 

 much as in Dicellomus and Obolus, also more or less imbricating con- 

 centric lines. The inner surface shows radiating and concentric lines 

 without the visceral area. Shell substance corneous and probabl}^ cal- 

 careous. The shell is built up of a thin, outer surface layer and sev- 

 eral inner layers or lamella?, slighth' oblique to the outer surface on 

 the laiibo and central parts of the valves. The lamella are more 

 oblique and numerous toward the front and sides, and thus thicken the 

 shell over those parts. The average ventral valve has a length of 

 5 mm., width 6 mm.; dorsal valve, 5 mm. by 5 nmi. 



Ventral valve strongly convex, most elevated at the umbo, and 

 arching over to a minute, slighth" incurved apex; area rudimentary, 

 with a high, triangular, open delthyrium occupying most of it. A 

 cast of the interior of the valve shows that a narrow elevated ridge 

 occurs just in advance of the apex. 



Dorsal valve evenly convex, apex marginal. The interior shows a 

 median ridge and septum, with small rounded depressions beneath the 

 umbo on each side of the median ridge and a little in advance of the 

 apex. Ventral nmscle scars small and clearl}^ defined. Anterior lat- 

 eral scars small, and situated in advance of the central scars close to 

 the median ridge and at its anterior extremity. Main vascular sinuses 

 broad and slightly defined. 



Ohsenmtions. — This shell was \ahe\ed Dlcello))ms 2)oUtus. In exter- 

 nal form it resembles it, but the open delthyrium of the ventral valve 

 and the absence of area on dorsal valve distinguish it. It appears 

 to be a form intermediate in development between Mustella and Dicel- 



