368 Viscount cI'Archiac and M. de Verneuil's 



planes (^plans), which terminate there. Although we are only j^et acquainted with a single individual of 

 this species, it appeared to us to be too evidently distinct from all its congeners to leave it undescribed*. 

 PafFrath ; very rare. 



5. Terehratula ferita, de Buch, Mem. de la Soc. Geol. de France, t. iii. PI. XVII. f. 4, p. 182. Tab. nost., 



XXXV. f. Sb, var. f. 3, 3a. 



Our variety is so completely distinguished at first sight from the type of T. ferita, that it might be re- 

 garded as a species if it did not vary much in itself, and if there did not exist sufficiently numerous in- 

 termediate varieties to establish a specific identity. This variety (fig. 3.) is less rounded than that de- 

 scribed by Von Buch. Tiie elongated beak is straight and the aperture altogether terminal. The area 

 is much elevated, and divided in two by a linear deltidium. On each valve there are seven unequal folds, 

 which are very distinct, rounded, and not always symmetrical. In one of the individuals represented at 

 fig. 3, the middle of the front does not exactly correspond to any one fold or groove, while in the other 

 (fig. 3 a.) is to be seen a small central fold corresponding to a groove in the ventral valve. Transverse 

 striae, concentrical, regular and pretty distinct, particularly toward the edge of the valves. The surface 

 of these latter, as well as of the area and of the deltidium, are very finely and elegantly punctulated. 



We have also represented (fig. 3.) an individual belonging to the type of the species, of which, the 

 ventral valve being partially destroyed, the spires turned outwards are seen ; a character which had long 

 been regarded as peculiar to the Spiriferce. 



Eifel, Villmar, Plymouth, Newton, Barton. 



6. Terehratula lepida, Goldf. Bonn Mus., Tab. nost., XXXV. f. 2,2 a, 2 b, 2 c. 



Shell very small, oval, sometimes globular. Ventral valve elliptical. Median sinus wide, shallow, li- 

 mited by two rounded folds on each side. A straight filiform fold at the bottom of the sinus. Con- 

 centric striae regular, and a little squamose. Dorsal valve ventricose, subcarinated, furnished with 

 three rounded folds on each side of the dorsal sinus, which is shallow. Strias similar to those of the 

 other valve. Beak extremely small. Aperture placed beneath, and touching the ventral valve. 

 Length, 6 millim. ; width, 5 ; thickness, ■i. 



Its form would bring this species into Atrypa of Dalman, if that genus could be preserved in a scien- 

 tific classification, which we think it cannot. 



Eifel ; rare. 



Strt/gocephalus. 



Although this genus belongs evidently to the order o'i Brachiopoda, the shells of which it is composed 

 present characters, both internally and externally, which distinguish it equally from the Terebratulce and 

 the Spiriferi. De Buch is disposed to refer the StrTjgocephali to the first of these genera, in which they 

 would compose a small group with the Terebratula Gryphus. We have, nevertheless, preserved to them 

 the name by which they are generally known. 



1. Stnjgocephalus Burtitii, Defr. Diet, des Sciences Nat., tome li. p. 102. PI. LXXV. f. 1, 1 a—€. Bronn, 



Leth. Geog., PI. II. f. 5. Terebrat. porrecta, Sow. Min. Con., PI. DLXXVI. f. 1. Terebr. Strygo- 



cephalus, de Buch. Mem. Geol. Soc. de France, t. iii. p. 230. 



Like most of the Brachiopoda, the Strygocephali present variations the limits of wliich it is difficult 



to ascertain. Sometimes the form of the area and the curve of the beak vary so much as to have caused 



the establishment of distinct species. Thus the S. rostratus is really nothing more than a variation of 



the S. Burtini, in which the very recurved beak hides a part of the area and almost touches the ventral 



* Since this description was in type M. Goldfuss has seen our plates, and he has informed us that 

 Terebratula cdiqua is the T. amygdalina of the Bonn Museum. Auf. 1842. 



