130 Reviews — Page's Economic Geology. 



Vienna and Dresden Museums being an inch long. Those from 

 Blackdown seem occasionally to have attained a greater size, but 

 never approaching the size of the European forms just mentioned. 

 It is the smallest Aporrha'is of the group. 



The following allied forms are figured in various works, but their 

 identity with A. calcarata of Sowerby is uncertain, and they seem 

 to be intermediate between this form and A. carinata. 



B. stenoptera, Goldf. Greensand, Aachen. 



B. Bnchii, Miinst., Geinitz. 



? B. calcarata (Sby.), Geinitz, Eeuss. Zekeli. 



B. composita, Leymerie. 



A. Muleti, D'Orb., Pictet and Campiche. 



J. M tiller, in the Monogr. der Petrefacten des Aachen Kreidefor- 

 mation, figures a remarkable assemblage of Aporrha'ides that are near 

 to A. calcarata, but some with monstrous forms of wing, see 

 especially Str. arachnoides, figured by Geinitz in his Quadersand- 

 steingebirge, tab. ix. f. 5. They are : — B. minnta, B. arachnoides, 

 B. granulosa, B. furca, B. Nilssoni. 



EXPLANATION OF PLATE V. 

 Fig. 1. — Aporrha'is carinata, Folkestone. Full grown. From the author's cabinet. 

 N.B. — The spiral angle is apparently increased, owing to the specimen 

 being slightly flattened. 

 Fig. 2. — A. elongata, Folkestone. 



Fig. 2a. — Portion magnified. Both from the author's cabinet. 

 Fig. 3. — Spire of A. elongata. From Mr. Price's collection. 

 Fig. 4. — A. maxima, Folkestone. From a fragment in Mr. Price's collection. 

 Fig. 5. — A. carinella, Folkestone. Ventral side of a full-grown specimen. 

 Fig. 6. — A. carinella. Dorsal view of another specimen. 

 Fig. 6a. — A portion magnified. Both from the author's cabinet. 

 Fig. 7. — A. calcarata, specimen from Blackdown, showing varices. In the Brit. Mus. 

 Fig. 7a. — Portion enlarged. 



Fig. 8. — Specimen with faintly marked ribs. In the British Museum. 

 Fig. 8a. — Same, enlarged. 



Fig. 9. — A pupseform specimen. In the British Museum. 

 Fig. 10. — Specimen from Folkestone, from an Upper Bed of the Gault. In the 



author's cabinet. 

 Figs. 11, 12, 13. — Specimens from the usual Lower Bed, Folkestone. From the same. 

 Fig. 13a. — Same, enlarged. 



Fig. 14. — A specimen from the same, enlarged twice. In the British Museum. 

 Fig. 15. — Specimen from Blackdown strongly ribbed. In the British Museum. 

 Fig. 15a. — Same, enlarged. 

 Fig. 16. — Specimen with bifurcated wing from Blackdown. In the Brit. Museum. 



(To be continued in our next Number.) 



BEVIE "W S. 



I. — Economic Geology; or, Geology in its relations to the Arts 

 and Mantteacttjres. By David Page, LL.D. 8vo. pp. 836. 

 (Edinburgh and London : Blackwood and Sons, 1874.) 



IT has been said that the ultimate aim of geological inquiry is to 

 restore in imagination the physical geography of by-gone periods ; 

 to restore, however dimly, the former extent in different times of land 



