86 BRACHIOPODA. 



Magas, Sow. Min. Conch. 1816, t. 119. 

 Terebratula, § C, Blainv. Diet. Sci. Nat. liii. 145, 1828. 

 Terebratulidpe, § 2, Gray, Ann. ^- May. Nat. Hist. 1848, ii. 435. 

 Wiegm. Arch. 1849, 98. 

 Loven, Arsb. 1848 and 1849, 213, & p. 8. 

 Terebratulidse, part., et Magasidae, part., D'Orb. Ann. Sci. Nat. 



1847. 

 Terebratula, Retzius, Gen. 



Mr. James Sowerby the elder gives a " partial longitudinal 

 septum with appendages attached to the hinge within," as the 

 character of the genus Magas, which is that of the whole tribe. 

 He first pointed out the advantage of studying the internal ap- 

 paratus, and observed in 1816, " It is much to be wished that 

 some person wouUl pubUsh an account of the curious internal 

 appendages of these shells." — Mineral Conch, t. 119. 



M. de;Blain^'ille in 1828 {Diet. Sci. Nat. liii. 145) used the 

 form of the internal apparatus to divide the Terebratulse into six 

 divisions. Section A. " Gripus, Megerle " = Terebratuhnina. 

 B. := TerebrateUa. C. = Terebratuhnina. D. = Megerlia. 

 E. = Bouchardia. F. = Argiope. 



The genera into which the Magasina have been divided depend 

 chiefly on modifications of the internal skeleton ; these do not 

 always correspond with the peculiarities of external form, or the 

 character of the foramen and deltidium. 



4. TEREBRATELLA. 



Loop elongated, reflected, doubly attached ; — to the hinge- 

 plate, and also to the longitudinal septum by processes given 

 ofi' at right angles from the crura, near the centre of the valve. 



TerebrateUa (chilensis), D'Orb. 1848, Ann. Sc. Nat. viii. 67. 



King, 1849, Permian Fossils, 81. 144. 



Dav. 1852, Ann. Nat. Hist. p. 366; Mon. Cret. p. 24. 

 Terebratula; loricate, Buch, 1834, iiber Terebrateln. 



Quenstedt, Handb. p. 463. 

 Terebratula (dorsata), Retzius. 

 TerebrateUa (dorsata), D'Orbigny, Paleont. Frang. 

 Delthyris (dorsata), Menke, Syn. ed. 2. p. 96. 



