48 BRITISH CRETACEOUS BRACHIOPODA. 



yet discovered in the Upper Green Sand; others, such as Nilsson, 1 Hisinger, 2 and Rcemer, 3 

 refer to Sowerby's species quite another shell from the Chalk, all three referring to 

 the same figure of Nilsson. M. D'Orbigny admits, in his 'Pal. Tran.,' pp. 103-4, 

 that those authors are mistaken, and places their T. ovata as a synonym of T. Carnea, but 

 M. D'Orbigny figures and describes in page 99, under the new name of Terebratula 

 lacrymosa, Sowerby's Ter. ovata, with which he was unacquainted. We regret being 

 obliged to deprive that author of his supposed new form ; but, as Sowerby's shell was 

 figured and described in 1812, and as it is well known, we cannot give priority to that by 

 M. D'Orbigny published in 1847. 



More than two hundred specimens of this type have been minutely examined by 

 myself from the dimensions of 2 to 19 lines; in young, and even in some more advanced 

 ages, there are no traces of the longitudinal depression, sometimes so very deep in adult 

 shells, as may be remarked in figs. ] 1 and 12, PI. IV; the first appearance in the young 

 is a slight depression, only quite near the margin. 



Sometimes, as may be remarked in fig. 9 of the same Plate, up to a certain age, the 

 valves were regularly convex, when a sudden stoppage in the growth occurred ; and, on its 

 being resumed, they at once presented a strongly marked depression extending to the 

 front; this species is generally much depressed, but in some exceptional cases assumes great 

 convexity, the width and depth being about the same as in fig. 12; but, as will be 

 observed, the characters of the form are there as well preserved as on figs. 10 and 11, 

 which may be taken as good types of the species. Sowerby's figure unfortunately does 

 not exhibit this depression, and more resembles fig. 8. We regret not having been able to 

 study the interior, our attempts having failed from the nature of the matrix ; but we are 

 disposed to believe, that the calcareous appendages were not arranged as in true Terebratula, 

 perhaps more like what we find in Kingena lima; the external structure being somewhat 

 similar, leads me to imagine them closely related; but, as it is of no use shifting species 

 until we are certain of their true place, we will allow T. ovata to remain for the present 

 in the genus Terebratula. 



T. ovata has been discovered by M. D'Orbigny in the Lowest Green or Chloritic beds 

 of Cap la Heve, near Havre; this bed and locality contains the same species we find at 

 Chute, near Warminster. 



Plate IV, fig. 6. A very young shell, from near Warminster. 



,, fig. 7, 8. Two specimens from the Chloritic Marl of Chardstock, in the 



collection of Mr. Morris. 

 „ fig. 9. A specimen, showing a sudden stoppage of growth, &c, from the 



Chloritic Chalk of Chard, in the collection of Mr. Moore. 



1 'Petrefacta Succana,' 1827, pi. iv, fig. 3. 



2 'Leth. Succ.' 1837, pi. xxiv, fig. 3. 



3 'Die Vers. Nord.,' 1840, p. 43. 



