44 



BULLETIN 65, UNITED STATES NATIONAL MUSEUM. 



arising at suumiit of stems by dicbotumy, tbe brancbes lilcewise dicbotomizing, 

 the total uumber of divisions, including tbe primai\v, being five or six. lu 

 form they are U-shaped. Branches 0.3 mm. wide throughout, except at the 

 extreme base where 4.0 mm. is reached. Peduncle O.G mm. wide. Branches set 

 in the proportion of 27 in 25 mm. Dissepiments fairly numerous, being, in some 

 places, as close together as 1 mm. 



Horizon and locality. — One specimen from the Xiagaraii chert, 

 Hamilton, Ontario. 



ODONTOCAULIS OCCIDENTALIS Gurley, new species. 



Giirley'n description and remarks upon this new species are as 

 follows: 



Polypary pedunculate-cyatbiforni showing in both specimens an under layer 

 separated by a " cliff " of rock from and exactly corresponding to the upper 

 layer, as in Dictyoncma, originating in a stem plainly thecaphorous. but not 

 preserved as far down as the disk, with a virgula (V)" 0.2 mm. wide. Stem 

 0.8 mm. wide to the apices of the thecje; 0.6 mm. to the bottom 

 of the depressions. Greatest height seen 38 mm., of which the 

 stem takes ui» 11. Thec;e 40 in 25 mm. I'olypary spreading 

 at once unilaterally, almost rectangularly, from the summit 

 of the stem and a little higher up for about 30° to the other 

 side. Branches 0.4 mm. in diameter, flexuous, set rather dis- 

 tantly and quite variably, but mostly about 25 in 25 mm. 

 Dissepiments present, but few and remote. Thecae visible in 

 few places on branches. 



Besides the above characters, the figured specimen shows the 

 basal disk, the initial dichotomous division at the summit of 

 the stem, dissepiments, and the cyathiforni character of the 

 polypary, the lower layer being visible underlying a '•cliff" 

 of rock. On the stem I think I can trace thecie, but they are 

 too obscure to speak certainly. 



-Niagara chert, Hamilton, 



Fig. oO. — Odon- 



TOCAL'LIS oc- 

 C I D EXTAL- 

 IS, NEW .SPE- 

 CIES. A RATH- 

 ER CO.MPLETE 

 RHABDOSO.ME. 



Hanson and locality. 

 Ontario. 



Coty pes. —Cat. No. 55306, U.S.N.M.; Walker Museum, University 

 of Chicago, No. 13514. 



Genus CYCLOGRAPTUS Spencer. 



f'i/fh,f/r(ii>tiis Spf.ncer. Canadian Nat.. X, 1882. p. 1(>5. nomrn nudum: 

 Proc. Amer. Assoc. Adv. Sci., XXXI. 1883, p. 365; Trans. Acad. Sci. St. 

 Louis, IV, 1884, pp. 563, 5!>2 : Bull. Mus. Univ. State Missouri. I. 1884, 

 p. 42.— Miller, North Amer. Geol. and Pal., 1889, p. 182.— Gurley, 

 Journ. Geol., IV, 1896, pp. 94, 309. — Kuedemann, New York State Mus., 

 Mem. 11. 1908, p. 182. 



*It certainly bears some appearance of being a true vii'gula. Were the 

 stem alone and the rock stated to be Lower Silurian, no one would hesitate to 

 pronounce it a virgula. But as this is the only case in these Upper Silurian 

 Dendroidea where I have seen any close resemblance to a virgula, doubt is but 

 natural. — R. R. Gurley. 



