ILLUSTEATIONS OF THE FAUNA OF THE ST. JOHN GROUP. lOl 



Mr. Billiugs has remarked upon the close resemblance of his species to O. perveta, 

 Conrad, of the Chazy and Black R. limestone ; ' it however is more tumid and has higher 

 umbos. Billings would incline to unite the two if the interior markings should be found 

 to agree. Billings also compares O. Elcdra to the P]uropean species O. parva, Pander, and 

 considers them closely allied ; but from the type of that species as given by de Verneuil '' 

 it differs considerably, and the internal markings of the dorsal valve do not agree with our 

 variety. M. de Verneuil figures a variety, avellana, Vern., of O. parva, which is larger and 

 has more numerous ribs than the type, but it also is a more tumid shell, especially in the 

 dorsal valve. 



Orthis orthambonites. Pander, (PL VIL, fig. 4.) 



Orthis caUigramma, Dalm., var. orthamboniles, (0. or'.hambonites, von Buch), de Verueuil. Russia and the 

 Ural Mts., vol. ii., p. 207. PI. xiii., figs. 8 a tog- 



Ortliis orthambonites, Pander, Palœoz. Fossils, Billings, p. 77, figs. 70 a. b- c. 



This species' was found by Billings in the Levis limestones at Quebec. Our examples 

 agree with his in size, and are smaller than those figured by de Verneuil. The ribs are 

 sharply raised, and in sets, every second or third one being more prominent than the 

 others. 



Size. Length 6 mm., width 8 mm. 



Horizon and Locality. Same as the preceding. 



Orthis Euryone, Bill. ? var. (PL VIL, fig. 5.) 



Palseozoic Fossils, p. 78, figs. 71 a. b. — Var. Nat. Hist. Soc. of N.B., Bull, x., p. vii. 



I refer to this species with some hesitation, a little shell which differs from those pre- 

 viously described. It is of the size and shape of Billings's species, and has about the same 

 number of ribs, but the following differences are noticeable : the A'entral valve is some- 

 what carinated, the umbo is not remarkably large, and the beak projects decidedly beyond 

 the hinge line. 



Size. Length of the ventral valve 6 mm., width 6'5 mm. 



Horizon and Locality. Occurs with the preceding. 



Orthis Menapije, Hicks ? var. (PL VIL, figs. 6 a and b). 



Geol. Mag. London, vol. v., ]>. 314, PI. xvi., figs. 24-28— Var. Nat. Hist. Soe. of N.B., Bulletin x., p. vii. 



A large Orthis, vvith the form of this species, but of larger size, occurs in the grapto- 

 lite beds. Being in slaty layers the valves are flattened and the form is therefore not well 

 preserved. The cardinal angles are rounded, and the hinge-line about three-fourths of 

 the greatest width of the shell. Form of the ventral valve oblately orbicular, of the dor- 

 sal valve similar but angulated at the cardinal angles. Ribs very numerous and fine, 

 arched on the sides of the valve ; there are occasional larger ribs, separated by several 

 smaller ones. 



Sculpture. This consists of fine radiating strite (about 100 in number) of M'hich a few 

 are more prominent than the others. 



' Palœozoic Fossils, vol. i., p. 80. /(S^ p ^ / 



» Russia and the Ural Mts., vol. ii., p. 188, pi. 13, figs. 4a and 6. A^ rP^^ '^^ ' 



UJ 



