2 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.60. 



America, at least by normal marine sediments. In this connection 

 it is of interest to note that Ulrich ^ considers the Upper Monroe as 

 possibly Devonian in age, though placing it in the Upper Silurian. 



In addition to the organic types known from the Lower Devonian 

 and Upper Silurian of Asia and Europe the faunas of southeastern 

 Alaska contribute several forms of considerable stratigraphic and 

 paleontologic interest. It is purposed in brief papers to describe 

 some of the more striking and characteristic of these fossils mainly 

 that appropriate names be available for discussion of stratigraphic 

 correlations. It is hoped that in the future with more material 

 available a monographic study of the faunas will be made. 



Among the novel and interesting types found in the Upper Silurian 

 rocks the pentameroid brachiopods stand out prominently. A large 

 number of species referable to several genera range through several 

 thousand feet of sedimentary rocks. Where found they serve as 

 excellent horizon markers, the species as a rule being well differen- 

 tiated and having restricted individual ranges. Among these pen- 

 tameroids is one genus that is represented by a number of species 

 and as known ranges through 3,000 feet or more of calcareous sedi- 

 ments. As the genus is of considerable stratigraphic importance and 

 appears to be new it has seemed desirable to describe the genus, which 

 is here defined under the name Brooksina. As the type species of 

 the genus the species has been chosen which has been found most 

 abundantly and which shows all the characteristic and distinctive 

 features upon which the genus has been established. 



BROOKSINA, new genus. 



The genus in brief may be defined as a Pentameroid of the Gon- 

 chidiuin type with the relative convexity and size of the valves 

 reversed. It is to be expected that with a considerable number of 

 species represented forms will be found in which the relative propor- 

 tions and contours of the valves will approach those of Conchidmm. 

 As a matter of fact, there are one or two undescribed species which 

 are at present referred to Brooksina with a question. Even these, 

 however, are far from typical Oonchidmm. Indeed, it seems prob- 

 able that Brooksina was derived not from Conckidium, but a distinct 

 and closely related undescribed genus. The characteristics as given 

 below as distinctive of the genus are found consistently in several 

 well defined species represented by several hundred individuals. 

 Variants from the generic diagnosis as given will not at present be 

 considered otherwise than noting that they exist. The variants are 

 represented by a few specimens only which may ultimately with 



2 Ulrich, E. O., Revision of tlie Paleozoic System, Bull. Geol. Soc. America, vol. T2. 

 1911. pi. 28. 



