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



Fam. XI PHORID^E Gray. 



Gen. AUTODETUS nov. gen.^) 



1884 Anticalyptrcea Qdekstedt Handbucli der Petrefaktenkunde, 3e Aufl., 673. 



Shell broadly conical, sinistral, affixed icith the truncated apex to other marine bodies, 

 ichorls externally not visible, no suture, aperture narrow, transverse, with a blunt, toothlike 

 projection near the centre of the flat, umbilical surface. There is no umbilicus, the axis is 

 solid. 2'he shell is interiorly subdivided in bladderlike compartments along the exterior wall. 



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

 genera as Calyptrasa, 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 interior, the characteristic sculpture of the umbilical surface and 

 its peculiar way of fixing itself with the apex to the hard 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 i-ecent 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 surmised above, it may be que- 

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

 ther belong to the Phorida^ and to the genus Onustus. 



Autodetus calyptratus Schrenk. 



PL I fig. 17—24, pi. XXI tig. 57—60. 



Capulus calyptratus 1854. Sciirexk Uebersicht des Schichtensystems Liv- und Esthlauds, 83. 



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

 1854. I, 94. 



Calyptrcea calyptrata 1860. Eichwald Leth. rossica I,ii, 1104, pi. 51 f. 13. 



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



Trochita calyptrata 1867. Lindstrom Nomina fossil. Gotl., 23. 



Anticalyptrcea calyptrata 1884. Quenstedt Handb. d. Petief. 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 bluntly pointed apex, without 



') yivrodsTog, who has bound himself. 



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



3) Bull. Soc. Lin. de Normandie YI, 151. 



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



K. Vet. Akad. Handl. B.ind 19. N:o 6 24 



