204 FISSURELLID/E. 



Genus PUPILLiEA. 



Char. Gen. Molluscum gasteropodura, testa patellseformi, dorsali 

 interna ; testa3 foramine maximo, ovali ; margine basali, area, de- 

 pressa cincto. Obs. The species upon which this genus is 

 founded, has the peculiarity of a depressed insertional rim, re- 

 sembling that by which the valves of a Chiton are inserted into 

 the surrounding integument. The shell is covered by the mantle. 



Pupill^a aperta (f. 228, 229), Sowb. — Oblonga, subconica, 

 crassa, antice magis gibba, postice magis depress;!, grisea, inse- 

 qualiter nigro fasciata et punctata ; margine impresso, albo, tenui ; 

 foramine maximo, ovali. Obs. The nearest shell to this in form 

 is FissureUidea nigrata, but neither that nor any other has a 

 similar insertional rim at the base. 



Genus CLYPIDELLA. 



Char. Gen. Molluscum gasteropodum, testa patellseformi, dorsi 

 partem tegente ; testre foramine parvo, subcruciformi ; margine 

 antico elevato. Obs. The flat saddle-shaped character of the shell, 

 and its small size compared with the animal, and the different 

 appearance of the animal itself, are perhaps sufficient to justify 

 the separation of the two known species composing this genus 

 from the other Fissurellidce. 



Species of Clypidella. 



1. pustula (f. 209, 210, 211), Lamlc. — Testa subcirculari, de- 

 pressa, antice paululum angustata, margine elevato; emarginate 

 alba seu rosea, seu roseo radiatim fasciata, costis depressis, crebris, 

 concentrice striatis et interstitiis linearibus radiata ; intus alba, 

 margine crenulato ; foramine subcruciformi roseo marginato 

 prope marginem anticum posito. Obs. The ribs are depressed 

 and close together, and the anterior margin is a little sinuous aud 

 elevated. 



2. fascicularis (f. 212, 213, 214), Lamlc. — Sub-pyriformi, 

 gibbosa, antice subacuminata ; radiis rugosis, elevatis radiata ; 

 foramine subcruciformi, prope medium posito. Obs. Peaked in 

 front, not emarginated, with the ribs more rugose and rounded 

 than in C. pustula, and the fissure placed nearer to the centre. 



