l6o BRUSINA : PAPYROTHECA, A NEW GENUS OF GASTROPODA. 



has the form of a diminutive, crushed, and very thin conical paper 

 case"'; for it has the conical form of the case, the inrolled apex, the 

 wide oblique, very unequal mouth, as also the groove which runs in 

 a straight line from the apex to the mouth. I have therefore called 

 the genus Papyrotheca from irairvpos and 6i)kij. That Papyrotheca 

 belongs to the Gasteropoda is shown us by the apex of the shell. 

 We have, as already stated, considered the enormous multitude of 

 extinct and living Gasteropods already collected, but can only find 

 distantly related affinities. 



In considering the form we might well find a relationship with 

 the genus Crepidula, especially Spirocrypta, in so far that these 

 genera and Papyrotheca have in common a slipper-shaped form. In 

 particular Crepidula ( Spirocrypta ) pileum, Gabb, from the cretaceous 

 formation of California, appears to show a certain relationship. 

 Spirocrypta has also an inrolled apex, the left side of the mouth 

 bends towards the interior and forms a broad lamella or 

 septum, the right side also bends inwards, it reaches and partly 

 covers the just-mentioned interior septum. Although I had no 

 opportunity of comparing Spirocrypta with Papyrotheca in nature ; it 

 is certain that a real relationship is out of the question, for this 

 reason, that Spirocrypta was a marine gasteropod, while Papyrotheca 

 was an inhabitant of either fresh or brackish water. 



The apex of Papyrotheca is formed like that of Calyptrcea 

 chinensis (L.), but in the Calyptrcca it is crushed flat, as is the 

 shell, whereas in Papyrotheca the apex is extended, lengthened, and 

 therefore pointed, microscopic examination only showing that it is 

 not sharp, but blunt, or say digitate. For this same reason, we can 

 better compare the apex of Papyrotheca with that of the genus or 

 sub-genus Acella, Hald., i.e., with the recent Limncea (Ace/la) 

 gracilis, Jay, from North America, or with the fossil Limncea 

 (Acella) acuaria, Neum., from Slavonia. 



We might therefore say that Papyrotheca is a Limncea, imitating 

 the form of a Crepidula. 



Already the recent genus Lantzia, Jouss., shows a highly singular 

 habitat amongst the Limncea. Very different are also the fossil 

 genera Boskovicia, Brus., Lytostoma, Brus., Corymbina, Bukowski. 

 Valenciennesia, Rouss, is also related to this family, and with the 

 Limiiceidce, through Limncea ( Velutinopsis, Sandb.) velutina, Desh. 

 Papyrotheca is certainly the most distant from all, and therefore one 

 might perhaps form a separate family of Papyrothecidce, or at least a 

 sub-family Papyrothecidince. 



6 [The German " papierdute " really means a paper cornet, such as grocers use to wrap up 

 sugar, &c, in. — Translator.] 



