CONTRIBUTIONS TO PALEONTOLOGY. 293 



The Spirifera alta referred to in the preceding pages is an analogue of 

 the European carboniferous Spirifera cuspidata, having a similar elevated 

 area which is usually " slightly inclining forward or nearly rectangular 

 to the general plane of the dorsal valve. The fissure is high and narrow, 

 and is closed for two-thirds of its length from the apex by a concave 

 septum which is entirely independent of the pseudo-deltidium." On 

 page 249 of Vol. iv, Palceontology of New York, I have made the follow- 

 ing I'emarks under the description of the species : 



" This species is known to me only in the condition of casts of the interior, 

 and its usual appearance is illustrated in the figures on Plate xh'ii. Its general 

 aspect is much like that of the European Spirifera cuspidata, Martin; but 

 there are important dilfereuces by which it may be distinguished: these are, 

 the plications on the mesial fold, the larger area of the dorsal valve, and the 

 shorter extension and greater divergence of the dental lamellte by the sides of 

 the muscular impression. Some of these characters, I conceive, are not likely 

 to change to those shown by S. cuspidata. In the concave septum closing two- 

 thirds of the fissure from above, it resembles that species as described by Prof. 

 JM'CoY, who mentions the presence of a ' deep-seated pseudo-deltidium. 'f In 

 one of the figures given by Mr. Davidson and referred with doubt to this 

 species, J the casts shows a tubular jserforatiou in the filling of the fissure, and a 

 gutta percha impression from the same shows the mark of a foramen; but there 

 is no positive evidence of a septum which is so conspicuous in our specimens, 

 and which I suppose to be the feature characterized by Prof. M'Coy as a deep 

 seated pseudo-deltidium. In our species, I have not been able to discover any 

 correspoudiug pei foratiou; the only indication of this being the semi-cylindrical 

 impression along the centre of the fissure (in the cast), showing a callosity of 

 the septum behind the exterior wall. 



"In form and proportions, this species bears a very close resemblance to one 

 in the Waverly saudstone of Ohio, and also to one in the fine-grained sandstone 

 of Burlington, Iowa; but of neither of these have I the necessary material for 

 satisfactory comparison. It differs from the S. subcuspidata.\ of Schnur in 

 the plications on the mesial fold and sinus, and the wider area of the dorsal 

 valve; and also in the same characters it differs from the S. textus of the sand- 

 stone and argillaceous limestone near New Albany, Indiana." || 



■j- * * * # . triangular opening very large, often displaying the internal deep-seated pseudo- 

 deltidium (without perforation, leaving the only opening to the shell at its base); * * * M'CoT, 

 British Palaozoic Fossils, p. 426. 



J Mo7iograph of British Carboniferous Brachiopoda, Plate ix, flg. 1 and la. 

 ■ § Spirifer subcuspidatus, Hall, Geoiogical Report of Iowa, p. 646, Plate xx, flg. 6, is a dis- 

 tinct species, and apparently identical with S. textus, Hall, Tenth Report on the State Cabinet, 

 p. 160, 1857. See Nineteenth Report on the State Cabinet, for remarks on this species. 



II The latter species, before alluded to as a punctate shell, has the fissure partially closed by a 

 septum, and this is perforated near the apex by a circular foramen, which is continued in a longi- 

 tudinal tube behind the septum and opens into the cavity of the shell below. The margins of 

 the fissure are grooved for the reception of a pseudo-deltidium as in ordinary spirifers, and this 

 appendage is partially preserved in some of my specimens. 



