240 Mr. E. Billings on the Genus Athyris. 



been made by him and Mr. Gustos Dormitzer, of Prague. He 

 showed that some of the forms heretofore referred to Terehratula 

 had no opening in the beak for the passage of the muscle of adhesion, 

 and also that the distribution of their inner organs points to an 

 affinity with the non-attached genus Pentamerus. These inner 

 organs are borne by six partitions in place of a single calcareous 

 loop ; the spiral arms are not unrollable. 



"Through the separation of these forms (for which the name 

 Merista is proposed) from the genus Terehratula, an apparent con- 

 tradiction in the laws of palseontological distribution is solved, since 

 those smooth forms will now be separated which have heretofore 

 offered an apparent contradiction to the present views of these 

 laws." 



Lest I should not have expressed his views rightly in this 

 free translation, I give the original in the note below*. 



On page 160 of the same work there are some further re- 

 marks on the classification of the Brachiopoda, by Prof. Suess, 

 in which he refers to the genus Merista. No generic description, 

 however, is there given. It appears also that it was again 

 noticed in Leonhard's 'Neues Jahrbuch/ 1854, p. 127. I have 

 not at present access to that work, and do not know whether 

 the genus is described there or not : at all events, at the time 

 Mr. Davidson prepared the English edition of his 'General 

 Introduction,' Merista was not understood. 



Prof. King, in his 'Monograph of the Permian Fossils of 

 England' (1850), proposed to restore the genus Cleiothyins of 

 Phillips, apparently making it partly equal to Athyris, M'Coy. 

 But the specimen on which this arrangement was founded was 

 afterwards shown to Mr. Davidson, and by him identified with 

 T. scalprum, Barrande (now Merista scalprum), while Cleiothyris 

 was intended by its author as a substitute for Atrijpa. (See 

 Davidson's 'Introduction,' p. 85.) 



* " Herr Eduard Siiess theilte die Erfolge der Untersuchung einigcr 

 Brachiopodeu aus dem bolimischen Uebergangsgebirge mit, die er gemein- 

 schaftlich mit Herrn Gustos Dormitzer in Prag angestellt hatte. Er zeigte, 

 dass mehrere bisher zu den Terebratein gezahlte Formen an ihrer Spitze 

 keine OefFnuug fur den Anheftungsmuskel besitzen, und dass auch die 

 Vertheilung ihrer inneren Organe auf eine Verwaudtscliaft mit der eben- 

 falls nicht angehefteten Gattung Pentamerus hinweist. Diese inneren 

 Organe werden von 6 Wanden, statt von einer einfachen Kalksehleife 

 getragen ; die Spiralarme selbst sind nicht aufroUbar. 



" Durch das Lostrennen dieser Formen, fiir welche der Name Merista 

 vorgeschlagen wird, von der Gattung Terehratula, wird zugleich ein 

 scheinbarer Widerspruch in den Gesetzen palaontologischer Verbreituag 

 gehoben, da eben jene glatten Arten ausgeschieden werden, welche den 

 bisherigen Ansichten liber diese Gesetze am schrofFsten entgegengestanden 

 waren." — Jahrhucli der k. k. geologischen Reichsanstalt, Vienna, ii. pt. 4. 

 pp.150, 160: 1861. 



