T. Davidson — Tertiary Brachiopoda. 367 



is not, indeed, a descendant from the Cretaceous T. cornea, and from 

 which it can at times be scarcely distinguished. It is abundant in 

 the Older and Newer Pliocene of Sicily, is alive in the Mediterranean, 

 and apparently likewise so in the Gulf of Mexico ; for the Ter. Cuhensis 

 of Pourtales is evidently a synonym of the shell under notice. Small 

 Sicilian (Pliocene) examples of T. vitrea were figured by Scilla in 

 1759, and it abounds in many places near Messina. It is found 

 likewise in Quaternary deposits of the same district. 



T. vitrea varies much, and several of its varieties or modifications 

 in shape have been described as distinct species. Terebratula minor 

 (Philippi), T. elliptica, T. Benoitiana, T. Michelottina, T. Lyelliana, and 

 T. orbiculata (Sequenza), appear to me to be very nearly allied to 

 T. vitrea ; and further study with reference to their distinguishing 

 characters will be required. 



8. Terebratula minor (Philippi), PI. XVII., .Fig. 14. T vitrea, var. 

 minor (Philippi), Enumeratio Moll. Sicilias, vol. i., pi. vi., fig. 8, 1836. 



This small shell is exceedingly abundant in the Pliocene deposits 

 of Sicily, and is pretty constant in its dimensions, which are con- 

 siderably smaller than those of T vitrea^ In 1845 it received from 

 Calcara the specific designation of affinis ; Suess, in 1859, considered 

 it to be specifically distinct from T vitrea, and described it as pos- 

 sessing stronger valves and blunt margins,- and he further observes, 

 that Philippi had pointed out the constant differences between the 

 two. Its loop is exactly similar to that of T vitrea. This small 

 species occurs alive near the Island of Lipari, north of Sicily, and in 

 other parts of the Mediterranean. 



9. Terebratula Lyelliana (Sequenza), PL XIX., Fig. 5. Sicilian 

 Brachiopoda, vol. i. Memorie della Soc. Italiana di Scienze Naturali, 

 p. 23, pi. i., fig. 11, 12, 13, 1865. 



Externally this small shell much resembles T. minor; a slight 

 difference in its loop is assigned to it by Sig. Sequenza. It occurs in 

 the Upper Pliocene near Messina, and where it is rare. 



10. Terebratula Benoitiana (Sequenza), PI. XVII., Fig. 13. Sicilian 

 Brachiopoda, pi. ii., fig. 10. 



The interior has not been discovered, and exteriorly it bears much 

 resemblance to some specimens of T vitrea. It occurs in the Older 

 Pliocene near Messina, where it is stated to be exceedingly rare. 



11. Terebratula elliptica (Sequenza), PI. XVII., Fig. 12. Sicilian 

 Brachiopoda, pi. ii., fig. 11. 



This shell is said to be very rare, and to occur in the Older Pliocene 

 compact limestone of Gravitelli, Eometta, and Scirpi, in Sicily. Its 

 interior is not known, and it much resembles certain specimens of 

 T. vitrea. 



12. Terebratula Michelottina (Sequenza), PI. XVIII., Fig. 8. Sicilian 

 Brachiopoda, pi. ii., fig. 7, 8, 9. 



This shell is stated by Sig. Sequenza to be easily distinguishable 

 from T. vitrea by its circular shape, as well as by certain small 

 differences in the hinge -plate. It occurs in the Upper Miocene and 

 Lower Pliocene near Messina. 



