24 



BULLETIN 65, UNITED STATES NATIONAL MUSEUM. 



Cotypes.— Cut. No. 55297, U.S.N.M.; Nos. 13502, 13501, Walker 

 Museum, University of Chicaw. 



DICTYONEMA POLYMORPHUM Gurley. 



Plate 4, figure 4. 



Dletyonema icncUum Spencer, Trans. Acad. Sci. St. Louis, IV, 18S;4. pi. 1. 



fig. 13 (not the description, p. 576) ; Bull. Mus. Univ. State ^Missouri, 



I, pi. 1, fig. 13 (not the description, p. 26). 

 Cnli/iitoffraptus subn'tiformis (part) Spencer, Trans. Acad. Sci. St. Louis, 



IW pi. 4, fig. 2; Bull. Mus. Univ. State Missouri, I, 1884, pi. 4, fig. 2. 

 Dich/oniiHa polymorphum Gurley Ms., Ruedemann, New York State Mus., 



Mem. 11, in08, p. 158, pi. 2. flg. 3; pi. 3, figs. 4. 5, 6 ; p. 160, text figs. 



(;0-72. 



26 



Figs. 26, 27. — DiCTyoNEJi.\ polymokphujm Gurley. 26, Rhabdosome ketainixg disk 



(PLESIOTYPE) ; 27, A COMPRESSED SPECIMEN (HOLOTYPE) WITH CENTRAL PORTION. 



(See also Pl. 4, fig. 4.) 



Doctor Gurieys elaborate description of this species has been pub- 

 lished by Euedemann," but is repeated here for the sake of com- 

 pleteness : 



Polypary originally cyatliiforni, circular or flahellate on the rock, when 

 flabellate often evenly semicircular in the largest specimen seen, 85 mm. in 

 diameter; originating in and sessile upon a carbonaceous "disk," which in 

 one specimen is seen to have its walls riddled with pores. Branches measur- 

 ing 0.6 mm. in width on the average, hai'dly ever as narrow as 0.3 mm. (as 

 Spencer states them to average), 0.4 mm. being, with rare exceptions, the mini- 

 mum and 0.8 the maximum. Branches varying equally in character, being 

 sometimes nearly straight, at others irregularly sinuous, and inosculating, as 

 in Dcsmoffraptus. Occasionally the ad.iacent margins of two branches coalesce. 

 The branches end in long drawn out, spike-like points. Very often — usually, 

 in fact — shortly before their termination, they bifurcate, U like, the termina- 



a New York State Mus., INIemoir 11, 1908, p. 158. 



