384 THE AMERICAN MONTHLY [Dec, 



28. DRUPPULA. 

 Pores hexagonal, 12—15 on the half-equator drnpa. 



29. PEUNOCA-RPUS. 



Pores circular, very small, 40-50 on the half-equator spargianum. 



30. LITHATRACTUS. 



Meshes circular, 10-12 on the half-equator; surface thorny carduelis. 



Meshes irregular, roundish, 6-8 on the half equator, surface smooth . .lobatus. 



31. DRUPPATR ACTUS. 



Pores circular; surface thorny or papillose coronatus. 



Pores irregular, roundish; surface smooth la'vis. 



32. STYLATRACTUS. 



Pores circular, 10-12 on the half equator ca-rduus. 



33. XIPHATRACTUS. 



Pores circular, 7-8 on the half-equator spinulosus. 



Pores circular, 9-10 on the half equator; polar spines furrowed sulcatus. 



Pores irregular, roundish, 9-10 on the half-equator radiosus 



Three of the above genera were omitted from the key to the genera, namely, Caryosjahsera, 

 EUipfostyliis and Druppula. 



Caryosphaera should be inserted (on p. 226 of the Journal, August 1893), 

 after Cromyosphsera, thus : 



E. FIVE SPHERES OR MORE. 



Two inner medullary, three outer cortical.. Caryosphsera. 



EUipsostuliis should be inserted (on p. 227, same month and year,) be- 

 tween EUipsoxiphas and Lithomespilus, thus : — 



Two polar spines of different shape Ellipsostylus. 



The key to Druppula I give along with a new key to the whole family of 

 Druppi;lida as I find the classification given before was not correct. (See p. 

 228, same month and year, and make the correction). 



7. FAMILY, DRUPPULIDA, TWO SHELLS. 

 A. No solid spines at poles. 



Medullary shell simple ; surface smooth Druppula. 



Medullary shell double ; surface spiny Prunocarpus. 



J5. Two opposite solid spines at poles. 



Medullary shell simple ; spines equal Lithatractus. 



Medullary shell simple ; spines unequal Druppatractus. 



Medullary shell double ; spines equal Stylatractus. 



Medullary shell double ; spines unequal Xiphatractus. 



To be continued. 



