144 



BULLETIN 11, UNITED STATES NATIONAL MUSEUM. 



Hall as Stictopora hifurcata. A specimen, probably of the same 

 species, "was illustrated by Eichwald as Stictopora scalpellum (Lons- 

 dale), although this identification on my part is merely a guess, 

 based upon the fact that Eichwald's figured example came from the 

 island of Dago, and evidently represents the old condition of Pachy- 

 dictya hifurcata. At any rate, it is almost certain that Eichwald's 

 Stictopora scalpellum does not refer to the Wenlock species described 

 by Lonsdale. 



Although closely alhed to such species of PacJiydictya as P. elegans 

 and P. cyclostomoides, the present form may be distinguished, first, 

 by its regular parallel edged branches, usually 5 mm. in width, divid- 



FiG. 68. — Pachtdictta BirxrRCATA. a to g, Wiman's figttees of Rhikidictya boekholmiensis. a 



TO d, FOUE FEAGMENTS, NATUEAL SIZE; e, SUEFACE OF FEAGMENT, XIO;/, VEETICAL SECTION, XIO; g, 

 TEANSVEESE SECTION, XlO. BOEKHOLM DEIFT, "OjLE MyE, ISLAND OF GOTHLAND; ft TO J, EICHWALD'S 

 FIGUEES OF STICTOPOEA SCALPELLUM; Jl, FEAGMENT, NATUEAL SIZE; i, SUEFACE ENLAEGED; j, END 

 VIEW OF SAME. BOEKHOLM LIMESTONE, ISLAND OF DaGO. 



ing dichotomously at rather long intervals; second, by its large, oval, 

 thick-walled zooecia, of which there are four to four and one-half in 

 2 mm., measuring longitudinally; and third, by the broad, granulose 

 interspaces separating the apertures at both their ends and sides. 

 P. cyclostomoides has still larger zooecia and differs further in its 

 broader, more frequently branching zoarium. The othep species have 

 smaller zooecia and a different surface ornament. 



RTiinidictya ? horJcTiolmiensis Wiman is in all probabiHty a synonym 

 of the present form. This species is recorded by Wiman as a very 

 common fossil of the drift bowlders at Ojle Myr, on the island of 

 Gothland, and in the Borkholm hmestone at Borkholm, Esthonia. 



