ANIMALS. 137 
Genus Aérypa, Dalman,! 1827. 
This group is here limited to species resembling its type, the Azomia reticularis of 
Linnezus, 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 Atrypa 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 Refzia,” 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 Terebratula Adriem, De Verneuil. 
This interesting genus, well distinguished by the above characters from other 
Spiriferide, embraces some pretty species, such as Fefzia Baylu (Terebratula id., 
Davidson), &. Bouchardit (7. id., Dav.), Rk. Oliviant (T. id., De Vern.), and R&. Salteri 
(L. id., Dav.) Terebratula ferita, and some other spirigerous Terebratuleform species, 
I am strongly disposed to regard as belonging to the same genus. efzia, by its form, 
holds the same relation to the family to which it belongs as Hudesia does to Terebratu- 
lide. \t appears to be a purely paleozoic 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 fetzia we pass on to a group of shells, the last to be noticed in connexion 
with the present family. 
Genus Cleiothyris,* Phillips, 1841. 
Diagnosis—Generally lenticular in form; minutely punctured; with variously- 
characterised projecting lamine of growth. Spirals pectinated. Dental plates large 
1 Synonyms: (?) Hipparionyx, Vanuxem (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 Terebratula, in 1788. 
3 Mr. Morris was the first who noticed punctures in species (Tered. Adrieni, and 7’. ferita) of this genus. 
(Vide Quarterly Journal of the Geological Society, vol. ii, part i, p. 387.) 
4 From ‘dew, claudo ; @vpa, janua,” Phillips. The name is synonymous with Actinoconchus, M‘Coy 
(1844), and J. de C. Sowerby’s “ Section 1” of Dalman’s Atrypa (Min. Conch. vol. vii, p. 11 and 14); also 
in part with Athyris, M‘Coy. Professor Phillips in his ‘ Paleozoic Fossils,’ p. 55, proposed the name 
Cleiothyris as a substitute for Afrypa, 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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