>PODA. 



1 



-. idth Miinewhat ui-eatcr than half tht> lii^ht of -lit-ll; api-rture -lightly widrr 

 than hitfh. -ubpentagonal. In a transverse section the volutions are semicircular in 

 the <l"i-al half, with the umbilical slopes almost straight and the ventral side 

 broadly indented by the preceding whorl. The width of the last volution expands 

 from ', nun. to 1'J nun. in a specimen IS nun. high. In the same specimen the slit 

 has u length of 1C,.:, nun., and a width of about 0.7 mm. The slit-Land is concave, 

 bordered on each side by a delicate line, and crossed by numerous fine lunulu-. On 

 each side of the slit and band the whole exposed surface is covered by a strong and 

 sharply defined network, the deep meshes of which are so arranged that they 

 fi-Mii rows running in two directions, one almost directly across the volutions, the 

 other obliquely forward and outward from the band. Finally, in certain lights, a 

 third arrangement of the meshes will be observed, namely, in series passing 

 obliquely forward from the sides to the slit-band. The last direction is approxi- 

 mately at right angles to certain more or less distinct lines or varices of growth 

 which interrupt the regularity of the network on old examples. (See figs. 43 

 and 44). 



i:\cepting the surface marking. It. I'uncl ifrons agrees very well with the typical 

 section of the genus. Even the retiform character of the sculpture is not entirely 

 foreign to lim-nnin, since a kind of reticulation is frequently observed in the B. 

 Ihnl.tlfyi section that would not require a very great modification to produce the 

 ornamental sculpture of the species under consideration. Still, we have no suspicion 

 that It. jnincti irons i- clo-ely related to any of the It. limlsleyi section. For the 

 present we consider it as a species standing entirely alone. 



formation and totality. - Tr-nt >n croup, at several localities in New York and Canada. The spori- 

 m->n* u[H.n which \h<- :I|KIV.- r|.-s<-ri|itii>n i- baaed were found in the lower part of the group ("Orthls bed") 

 near Nashville, Tennessee, by Prof. Jas. M. Safford. 



!'! \M.V NANA, n. xp. (l'lricli.) 



ri.\TK i.\\ : 44. 



II small, ID mm. or less iii bight, volutions two and a half or three, each 

 embracing more than half of the preceding turn, expanding gradually and with 

 moderate rapidity quite to the aperture, reniform in cross-section, broadly rounded 

 on the dorsum and rather narrowly where the surface descends into the umbilicus; 

 the latter is -mall, equalling only about oin'-fonrth of the greatest diameter of the 

 shell; aperture rounded when perfect, usually appeal -ing more or less reniform, scarcely 

 expanded, its width equalling about four-fifths of the hight of the shell; lips thin. 

 the outer one with a central slit probably less than J nun. in length, the sinus also 

 being unusually shallow, the inner lip prolonged slightly on each side and forming 



