LECTURES ON MOLLUSCA. 281 



Pyrula, Pyrulidce. Fulgur, Fasciolariadce. Rapana, Purpuridce. 

 Ficula. Ficulidce. 



Leucozonia, Fasciolariadce. Monoceros, Purpuridce. 



Mitra, Fasciolariadce. Turricula, Turriculidce. Volutomitra, Volu- 

 tidce. 



Aulica, Volutidce. Amoria, Do. 



Metula, f Muricidce. Daphnella, Pleurotomidce. 



Marginella, Marginellidce. Erato. Cyprceidce. 



Oerithiopsis, Cerithiopsidce. Fastigiella, ? Fasciolariadce. Cerithium, 

 CerithiadcB. 



Velutina, VelutinidoB. Capulus, Capididce. Otina, Otinidce. 



Sigaretus, Naticidce. Lamellaria, Lamellar iadce. Stornatella, Sto- 

 mal idee. 



Drillia, Pleurotomidce. Clionella, Melaniadce. 



Lunatia, Naticidce. Lacuna, sp. Lacunidce. Pachistoina, Ampulla- 

 riadce. 



Naticina, Naticidce. Narica, Naricidce. Fossarus, Litorinidce. 



Menestho, Pyramidellidce. Mesalia, Turritellidce. Melania, Melani- 

 adce. 



Aclis, Pyramidellidce. Turritella, Turritellidce. 



r f op-shells in general, e. g. : Solarium, Solaria-dee. Phorus, Phoridce. 

 Risella, Litorinidce. Trochita, Calyptrceid.ee. Trochatella, Helici- 

 nidee. 



Especially : Phorus, Phoridce, Guildfordia. Turbidce. Torinia, So- 

 lariadce. Monilea, Trochidce. Infundibulum, Trochidce. Trochita, 

 Calyptrceid.ee. 



Kostellaria, Strombidce. Aporrliais, Aporrhaidce. 



Tanalia, Paludinidce. Paludomus, Melaniadce. 



Vermetus, Vermetidce. Serpula, Annelids. 



Dentalium, Dentaliadce. Ditrupa, Annelids. 



Planorbis, Planorbidce. Marisa, Ampidlariadce. Polygira, Helicidce. 



Limpets in general, e. g. : Patella, Patellidce. Acmrea, Acmceidce. 

 Anialthea, Capididce. G-adinia, Gadiniadce. Siphonaria, Siphonari- 

 adce. Broderipia, Stomatidce. Umbrella, Umbrellidce. 



Especially : Nacella, Patellidce. Ancylus, Planorbidce. Latia, Pla- 

 norbidce. Crepidula, Calyptreeidce. Tylodina, Umbrellidice. Scurria, 

 Armceidce. 



Ampliibola, Amphibolidce . Scissurella, Scissurellidce. 



Achatina, Helicidce. Glandina, Testacellidce, &c. &c. 



A similar table might easily be prepared of shells very greatly dif- 

 fering in appearance, which are known to belong to the same family. 



This branch of study has been favored with quite a sufficient num- 

 ber of hasty generalizations to last for some time to come. What we 

 want now is patient verification of the past, and cautious observation 

 for the future. " Non omnes possumus omnia," and every man is not 

 bound to do his work well ; because he cannot ; but he is bound hon- 

 estly to use all the materials at his command. There is so much yet 

 to be known about the commonest land and fresh-water shells, in their 

 anatomy, habits, distribution, and specific differences ; and there are 

 so many materials hoarded up in museums awaiting the study of nat- 



