KONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND. 19. N:0 6. 185 



Fam. XI PHOPJD^ Gray. 



Gen. ÄUTODETUS nov. gen.^) 



1884 Anticalyptrcua Qdenstedt Handbucli der Petrefaktenkunde, 3e Aufl., 673. 



Shell hroadly conical, sinistral, affixed with tlie truncated ajpex to other marins bodies, 

 wliorls externally not visihle, no suture, aperture narroiv, transverse, with a hlunt, toothliJce 

 projection near the centre of the flat, umbilical surface. lliere is no icmbilicus, the axis is 

 solid. 2%e shell is interiorly subdivided in bladderlike compartments along the exteriör wall. 



This curious little shell has by its first describers been referred to several recent 

 genera as Calyptrsea, Capulus and Trochita, Avith none of which it, however, on closer 

 inspection can be regarded as related. This is chiefly found through the aspect of 

 the volutions in the interiör, the characteristic sculpture of the nmbilical surface and 

 its peculiar way of fixing itself with the apex to the härd structures of other animals. 

 In outward appearance it has certainly a great similarity to species of the recent genus 

 Galerus and also in some degree in the form of the aperture, which in some species of 

 Galerus have a tooth like prolongation. There seems, however, to be more reason to re- 

 gard it as a precursor of the recent Phoridaj. The shape of the aperture as well as the 

 ornamentation of the umbilical surface justify this comparison. But instead of fixing 

 other objects to its shell, as its recent relatives, it fixed itself to larger objects. 



This is, perhaps with exception of Clisospira, the oldest known representative of 

 this curious family, as there is before none older known than Xenophora or Pseudo- 

 phorus antiquus Meek^) and Phorus Bouchardi EuG. Deslongschamps ^) both from the 

 Devonian formation. Then none is found before the Jurassic time. Perhaps also Tro- 

 chita antiqua? Meek*) belongs to this family. But, as surraised above, it may be que- 

 stioned whether sucb Silurian shells as Trochus cavus, Tr. profundus etc. do not ra- 

 ther belong to the Phoridte and to the genus Onustus. 



Autodetus calyptratus Schrenk. 



Pl. I fig. 17—24, pl. XXI fig. 57—60. 



Capulus calyptratus 1854. Schrenk Uebersicht des Schiohtensystems Liv- und Esthlands, 83. 



1858. Fr. Schmidt Geol. Esthlands, 206, but not Patella mitreola Eichw. Bull. Moscou 

 1854, I, 94. 



Galyptrma ealyptrata 1860. Eichwald Leth. rossica I,ii, 1104, pl. 51 f. 13. 



1867. QuENSTEDT Handbuch der Petrefaktenkunde 2e Aufl., 526, f. 117. 



Trochita ealyptrata 1867. Lindström Nomiua fossil. Gotl., 23. 



Anticalyptrcea ealyptrata 1884. Quenstedt Handb. d. Petref. 3:e Aufl., 673. 



Shell irregularly conical, sinistral, with the truncated and affixed apex forming 

 a flat surface. A few large specimens from Lau and Hoburg seem to have freed 

 themselves at an early stage of growth and have a bluntl)^ pointed apex, without 



') ^Ainoåsiog, who has bound himself. 



-) Geol. Survey of Ohio, vol. I, 221. 



3) Bull. Soc. Lin. de Norraandie VI, 151. 



*) Proceed. Ac. Nat. Se. Philad. vol. 23, 82. 



K. Vet. Akad. Handl. Band 19. N:o 6 24 



