ANIMALS. 137 



Genus Atrypa, Dalman,i 1827. 

 This group is here hmited to species resembhng its type, the Anomia reticularis of 

 Linnaeus, in being generally ribbed or striated^ in having the large or foraminiferous 

 valve with flat or concave lateral regions and a broad median sinus, and in being 

 furnished with a slightly-developed apophysary system — the spirals excepted. Certain 

 varieties of Atri/pa reticularis — those with an area, and a projecting umbone forami- 

 nated at the apex, and bounded inferiorly by a deltidium (vide ante, p. 72) — in pointing 

 out the affinities of the genus, conduct us at once to another group of shells, now for 

 the first time elevated to a co-ordinate rank. 



Genus Metzia,^ King. 



Diagnosis. — A Spiriferidia ; in general oval longitudinally ; ribbed or striated ; 

 with large punctures.'^ Large valve foraminated at or near the apex of the umbone ; 

 with a triangular area, and a closed fissure. 



Type Terehratula Adrieni, De Verneuil. 



This interesting genus, well distinguished by the above characters from other 

 Spiriferida, embraces some pretty species, such as Metzia Baylii {Terehratula id., 

 Davidson), R. Bouchardii {T. id., Dav.), R. Olioiani {T. id., De Vern.), and M. Salteri 

 {T. id., Dav.) Terehrafida ferita, and some other spirigerous Terebratulreform species, 

 I am strongly disposed to regard as belonging to the same genus. Eetzia, by its form, 

 holds the same relation to the family to which it belongs as Eudesia does to Terehratu- 

 lidce. It appears to be a purely palaeozoic genus, being only found as yet in the 

 Silurian, Devonian, and Carboniferous rocks. Professor Phillips and Dr. de Koninck 

 have described two or more carboniferous species. 



From Betzia we pass on to a group of shells, the last to be noticed in connexion 

 with the present family. 



Genus Clciothyris^ Phillips, 1841. 



Diagnosis. — Generally lenticular in form ; minutely punctured ; with variously- 

 characterised projecting laminae of growth. Sjnrals pectinated. Dental plates large 



^ Synonyms : (?) Hipparionyx, Vanuxeni (vide Sharpe, ' Quarterly Journal of the Geological Society,' 

 vol. iv, part i, p. 180) ; Spirigerina, A. d'Orbigny, 1848. 



2 This genus is dedicated to Retzius, who published a ' Dissertation' on Terehratula, in 1788. 



^ Mr. Morris was the first who noticed punctures in species {Tereb. Adrieni, and T. ferita) of this genus. 

 (Vide Quarterly Journal of the Geological Society, vol.ii, part i, p. 387.) 



* From "cXeiw, claudo ; Qvpn, janua," Phillips. The name is synonymous with Actinoconctius, M'Coy 

 (1844), and J. de C. Sowerhy's " Section I" of Dalman's Atrypa (Min. Conch, vol. vii, p. 1 1 and 14) ; also 

 in part with Athyris, M'Coy, Professor Phillips in his ' Palaeozoic Fossils,' p. 55, proposed the name 

 Cleiothyris as a substitute for Atrypa, Dalman ; but as there are several cogent objections to the use of 

 substitute names, even if they be more correct or more euphonious than the original, the present one cannot 



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