436 CRETACEOUS PELECTPODA 



AMUSIUM, Klein, 1753, (seep. 426). 

 1. Amusium ? MEMBRANACEUM, Nilsson, PL XXXII, Pig. 5, and PL XLI, Figs. 7-8. 



1827.' Pecten memhranaceus, Nilss,, Petrif. Suec, p. 23, pi. ix, fig. 16. 

 1866. Idem, Zittel, Denkscla. Akad., Wien, xxxv, pt. ii, p. 107, cum. syn. 



Am, testa ovato-orbiculari, cequivalvi, valde complanata, suh-cequilaterali, tenuis- 

 sima, Icevigata aut concentrice subtiliter striata, nitida ; auricidis fere cequalihus, 

 postica oblique desinente, antica subtruncata. 



The Indian specimens do not exhibit any difference from the European ones. 

 The superficial glassy layer is, as a rule, quite smooth, but when it has been removed 

 by decomposition, the shell exhibits a number of very fine radiately arcuate lines. 

 The gape of the valves must be very slight, if indeed it is at all marked, but the 

 structure of the shell appears to be that of Amusium, 



Localities, — Arrialoor and Karapaudy, in grey sandstone ; rare. 



Formation, — Arrialoor group. 



In Europe this species belongs to one of the commonest shells in the upper 

 and middle (Turonien) cretaceous beds ; it has been recorded from Sweden, Hanover, 

 at Maastricht, from near Aachen, in Saxony, Bohemia, at Lemberg (in Galicia), in 

 the Alpine Gosau deposits of Lower Austria, in Bavaria, &c. 



2. Amusium illustre, StoUczlm, PL XLI, Pigs. 9. 



Am, testa magna, sub-orbiculari, valvis convexiusculis, crassis, ad umbones late 

 obtusatis, Icevibus, striis incrementi incequalibus, partim sub-obsoletis tectis ; auri- 

 culis sub'Cequalibus, magnis, oblique truncatis. 



One of the largest known cretaceous species of the genus, distinguished by 

 a strong, solid, almost smooth shell, obtuse umbones, and considerable convexity of 

 the valves; the ears are large and apparently very nearly equal. The valves appear 

 to have been slightly gaping at both ends. 



Locality. — West of Arrialoor, in light grey sandstone. 



Formation, — ^Arrialoor group. 



3. Amusium sulcatellum, Stoliczha, PL XXXI, Pigs. 12 and 17. 



1846. Fecten orbicularis, Sow.? apud Eorbes, Trans., Geol. Soc, Lond., vii, p. 154, non idem Sow. 



Am, testa sub-orbiculata, valvis crassiusculis, cequilateralibus, parum convexis 

 ad latera deplanatis, concentrice sulcis angustis aut lineis impressis subdistantibus 

 concentricis, confertis, notata, cequidistantibus, lateraliter minus distinctis, interstitiis 

 planatis, sulcis multo latioribus, concentrice minutissime striolatis ; auriculis sub- 

 cequalibus, postica paulo minore, oblique et sub-flexuose terminante, antica majore, 

 rectius truncata, 



A sub-compressed, nearly orbiculate species of the type of A, orbicular e, Sow., 

 but with somewhat more acute umbones and much thicker shell. The ornament- 



