260 



Lingula Rodriguezii, Rathhun, sp. nov. 



Dorsal valve rather large, elongate, and oblong in outline. Front very sliglitly 

 rounded, but curving somewhat strongly to meet the lateral margins, which, 

 curving but slightly, extend backwards nearly parallel with one another for 

 about three-fourths the length of the valve. The posterior lateral margins 

 incline towards one another at an angle of about 100 degrees, and the beak is 

 apparently a little rounded. The outline of the valve is very defective, but I 

 have been able, I think, to trace it out very satisfactorily from the rather 

 numerous lines of growth, which are quite well preserved on the front ; but 

 the valve is so crushed that it is impossible to determine its convexity. 



The impressions of the several muscular markings are more or less perfectly 

 preserved. They show that the valve is dorsal. The impression of the pedicle 

 muscle is not preserved, but just in front of the place where it should be, are 

 two small crescent-shaped impressions, placed closely together and apparently 

 more deeply excavated in the substance of the test than are the other muscular 

 markings. The markings left by the decussating muscles seem to be narrow 

 and elongate, but the outline is indistinct. They are apparently situated at 

 the sides of a raised, circular disc, from the front of which extends a short, 

 low and rather broad median crest, but the test is so broken that the appear- 

 ance of a disc and crest may not be natural. On each side of this crest are the 

 impressions of the posterior adductors, which seem to be unusually small, 

 while the subelliptical impression of the anterior adductors in front of the 

 crest is also very small^ One or two narrow, faint, curving depressions 

 extend forward from the front of the impressions of the decussating muscles, 

 and probably denote structure. There is a V-shaped line on the forward por- 

 tion of the disc, apparently of the same character. Length 23 m. ni., breadth 

 13 m. m. 



Obtained from the yellow sliale underlying the sandstone at Erere. 



Dedicated to Dr. J. C. Eodrignes, Editor of the Novo Mnndo, 

 New York, one of the most prominent patrons of the Morgan 

 Expeditious of 1870 and '71. 



Although the fossils so far obtained from Erere, were collected 

 from so small an area and so limited a thickness of rock as to ren- 

 der it unsafe to draw any extended or definite conclusions from 

 them ; yet the Brachiopod fauna, such as it is, resembles so closely 

 that of the Hamilton group of New York State, as to leave no 

 doubt that the beds in which it was found, the sandstones and shales 

 of Erere, represent about the same horizon as the Hamilton group 

 of North America. Not only are characteristic Hamilton group 



