212 THE AMERICAN MONTHLY fJuly, 



139. SETHOPERA. 

 Cephalis pear-shaped ; thorax also, with roundish pores lagena 



140. MICROMELISSA. 



Shell smooth ; wings from upper part of thorax microptera 



Shell rough ; wings from lower part of thorax ventricosa 



141. PEROMELISSA. 



Shell rough ; two joints ovate of nearly equal size capito 



142. TETRAHEDRINA. 



Shell three-sided, pyramidal, smooth pyraniidalis 



Shell pear-shaped, papillate quadrioornis 



143. SETHOCHYTRIS. 



Shell smooth ; thorax conical ; with 3 fenestrated cones half a.s long 



as thorax barbadensis 



Shell smooth ; thorax pyramidal ; with 3 pyramidal fenestrated feet, 



nearly as long as thorax pyramis 



Shell rough ; thorax pear shaped ; with three fenestrated cones, about 



as long as thorax triangula 



144. SETHAMPHORA. 



Shell smooth ; thorax nearly ellipsoidal, with 18 ribs mongolfieri 



Shell spiny ; thorax inflated, with 20 dentate ribs ampulla 



Shell smooth ; thorax inflated, with 22-24 smooth ribs aerostatica 



145. SETHOPYRAMIS. 



Shell with 6 radial main beams (sometimes with .5 or 7) scalaris 



Shell with 9 radial main beams (sometimes with 8 or 10) quadratella 



146. PLECTOPYRAMIS. 



Shell with 6 ratlial main beams (sometimes with 5 or 7) maguifica 



Shell with 9 radial main beams (sometimes with 8 or 10) fene-strata 



147. ACANTHOCORYS. 



Thorax with G divergent ribs butschlii 



148. ANTHOCYRTOMA. 



Shell pear-shaped, rough, with obliterated collar stricture serrulata 



149. ANTHOCYRTIS. 



Feet divergent, trangnlar, about as long as thorax mespilus 



Feet divergent, curved, forked, about as long as shell furcata 



Feet divergent, conical, about l-5th the diam. of shell ventricosa 



Feet parallel, conical, about as long as cephalis grossularia 



