432 Forty-second Report on the State Museum. 



distinctly septate Spirifers, which are represented in the Upper 

 Helderberg by the closely allied S. raricosta, in the Hamilton by S. 

 zic-zac and S. sculptilis, all in the line of development toward Spiriferina. 

 The post-Silurian long-winged group is represented by the same 

 species. In S. perlamellosus again, and in S. cycloptera and S. concinna 

 we find a strongly lamellose ornamentation which has its inception in 

 the Niagara S. salcatus, but is represented in the Devonian by an 

 abundance of forms e. g. S. • submucronatus, Cumberlandice, tribulis, 

 arrecta, of the Oriskany, S. raricosta, duodenaria, of the Upper Helderberg, 

 8. mucronatus, zic-zac, sculptilis, Hamilton, etc. The lamellose forms of 

 the Lower Helderberg retain evidence of Silurian relations in the fine 

 interrupted striae on the lamellae, a feature also seen in S. arrecta of 

 the Oriskany and 8. raricosta of the Upper Helderberg, but not usually 

 present in the more numerous Devonian species. S. macropleura, 

 with its finely lineate surface, follows more closely the Silurian type 

 of S. plicatellus and S. Niagarensis, presenting, however, a deviation 

 therefrom in its few great ribs. This lineate type is not known in 

 the American Devonian, but is represented in the European Lower- 

 Devonian by S. Davousti and others. The smooth un ribbed non- 

 fimbriate type of Marhma, essentially Carboniferous in its culmination, 

 is represented by S. modestus, which may be regarded as its earliest 

 member. Cyrtina Dalmani, together with G rostrata of the Oriskany, 

 (?) G biplicataoi the Schoharie grit, G. crassa of the Corniferous and G. 

 Hamiltonensis and var. recta of the Hamilton, represents a series of 

 unessential variations, which in European faunas pass under the name 

 of G heteroclita, Defrance, and its varieties, multiplicata Davidson and 

 kevis, Kayser, forms ranging from the Lower into the Middle-Devonian 

 and common in the Eifel, Belgium, France and Eogland. The varia- 

 tions of G Dalmani are most closely those of the Hamilton species. 

 The genus is not represented in the Silurian. 



Trematospira is represented by several species, one of which ( T, mul- 

 tistriata) is of very considerable size and closely related to the Hamil- 

 ton T. hirsuta. All are in contrast to the few small species of the 

 Silurian. 



Nucleospira is well developed in both Silurian and Devonian faunas. 

 The species of the former (N. pisum, pisiformis) are small and rotund, 

 while those of the Devonian are larger and less convex (N. concinna). 

 Both groups are represented in the Lower Helderberg, the former by 

 N. ventricosa, the latter by N. elegans, concentrica. Of the Meristoids, 

 no true Meristina or Whitfieldia is known to occur in the group. 

 Merista is represented by two species in the Maryland fauna, and aside 

 from these it is probable that all the abundant meristoids of the fauna 



