THE BRITISH FOSSIL BRACHIOPODA. 371 



species itself is of a very problematic nature as to its generic relations, and it is very 

 doubtful if the figure in Woodward's 'Manual' represents what was assigned by de Koniuck 

 under the name. Dall has, therefore, very properly considered Retzia vera, Hall, as the 

 type of the genus, which species, somewhat earlier in the text (page 55), was figured by 

 Hall as a representative of the serpentina type. If we take this species as the type, we 

 can then find out approximately what is denoted by the name." 



Anyhow, rightly or wrongly, Dr. Waagen considers the Eumetria yrandicosta 

 {Retzia radialis, Phil., var. yrandicosta, Dav., ' Quarterly Journal Geol. Soc.,' London, 

 vol, xviii, p. 28, pi. 1, fig. 5, 1862) as a type of the genus, and gives a detailed 

 description, accompanied by figures showing the spirals and their connections, which 

 we here reproduce, as it is desirable to record all that has been discovered on this 

 important subject. Dr. Waagen says that it is highly probable that the Indian species 

 of the genus are in a developmental connection with the respective European species. 

 We have thus (Waagen, op. cit., p. 490, &c.) : 

 I. Group of Eumetria radialis, Phil., sp. 



1. Eumetria yrandicosta (Dav., sp.), Waagen. 

 II. Group of Eumetria ulotrix, Kon., sp. 



2. Eumetria indica, Waagen. 



The real type of Retzia is the Retzia Adrieni, de Verneuil, but hitherto it has not 

 been possible to obtain suitable specimens so as to be able to develop its interior 

 character, and consequently the Retzia Salteri has been the species upon which the 

 characters of the genus have been described by Mr. Glass and myself. They differ in 

 several respects from the figures and description given by Dr. Waagen of Eumetria as 

 typified by the so-termed Eumetria yrandicosta. 



" The internal characters of the shell," says Waagen, at p. 488, " are very peculiar. 

 The ventral valve is very simple inside : from the straight hinge-line there project, not 

 far distant from each other, two small hinge-teeth, which are otherwise in no way 

 remarkable ; they are not supported by dental plates, and are not continued inside the 

 area as projecting ridges. . . . The dorsal valve has a very complicated brachial 

 apparatus. The cardinal process consists of a transversely elongate, squarish, upright 

 plate, which extends below the area of the larger valve, and between this plate and the 

 apex of the dorsal valve the median part of the area is so firmly wedged in that it is 

 impossible to separate the two valves without breaking off the middle part of the area, 

 which then remains sticking in its place, and can only with great difficulty be removed. 

 On both sides of this cardinal process are the dental sockets, which are very small for 

 the reception of the small hinge-teeth. Anteriorly and somewhat above the dental 

 sockets the crura take their origin. The cardinal process or hinge-plate, as one might 

 like to call it, is produced below into a stout hooked process, which is again supported 

 by a small semilunar septum, which latter, however, seems to be only rudimentary in 

 some cases. The hooked process shows much similarity to the curved tube which 



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