156 ON PERMIAN ENTOMOSTRACA FROM 



t^riorly in a blunt point; anterior extremity prominent, 



rounded, bordered by a flattened marginal rim ; posterior 



extremity diagonally truncate; lateral contour somewhat 



boat-shaped, tapering quickly in front, blunt behind ; 



greatest diameter in anterior half, at two-sevenths of 



length; contact-line of valves straight on both ventral 



and dorsal borders. 



A curiously similar but distinct species has been figured and 



described by K. von Seebach (" Zeitsch. Deutsch. Geol. Gesell. 



1857," p. 201, pi. 8, fig. 4), under the name of Cythere dispar, 



from the Keuper of Thuringia. 



Mr. Jones tells me that a tertiary species lias been named 

 Cythere truncata, by Bosquet, so it has been necessary to alter 

 the specific name of the present species, which I have done by 

 substituting amjmtata, as being similarly expressive of the trun- 

 cated appearance of its posterior extremity. 



C. amputata is rather rare in the shell-limestone of Tunstall 

 Hill. 



NOTE BY MR. T. R. JONES, ON CYTHERE AMPUTATA^ KIRKBY. 



We have here a very interesting and peculiar form, in which 

 the hinge-line is well developed : the anterior hinge, in particular, 

 being strongly marked externally, judging from the cast, which 

 also shows the dorsal margins of the valves peculiarly flattened 

 out. The compressed and obliquely rounded anterior border — 

 the central swelling of the valves — the straight and thin-edged 

 back, and the obliquely truncated hinder end, with its project- 

 ing dorsal angle, (the margins of the two extremities being 

 nearly parallel), characterise this species. (See pi. XL, fig. 22.) 



Besides the species of Bairdia, Cytherideis, and Cythere proper, 

 already noticed, there appear to be one or two additional forms 

 belonging to the fauna of the shell-limestone, which may subse- 

 quently be established as species. Specimens have occurred to 

 me which seem to imply this idea; but owing to a paucity of 

 materials, and in some cases to an ajoparent affinity to described 



