40 



BULLETIN 65, UNITED STATES NATIONAL MUSEUM. 



appear to repi'esent the position of a solid central axis. The terminations of the 

 branches end in two or three points. The branches in this species are very 

 delicate being about n quarter of a millimeter broad, and each branch is not 

 more than from 3 to 2 millimeters in length, before it 

 overlaps or touches the adjacent stipe. The greatest 

 diameter of the frond is not more than 4 cm. Only 

 two or three specimens of this beautiful little frond 

 I'.Mve been obtained. 



Formation and locality. — I obtained this species, 

 near the base of the Niagara dolomite, at a quarry 

 just west of the "Jolly-cut-road," Hamilton, Ontario. 



A single specimen of this species, repre- 

 sented in figure 50, is at present extant in 

 the Spencer collection. It does not permit of 

 an}^ substantial addition to the above descrip- 

 tion. The branches show some longitudi- 

 nal chitinous strise, but there are no indica- 

 tions of thec?p or dissepiments. 



Fig. 50. — CALYPTOcR.'iPTus 



MICRONEMATODES SPEN- 

 CER. PLESIOTYPE l.N 



Spencer collection 



CALYPTOGRAPTUS ? RADIATUS Spencer. 



Calyptograptns ? radiatus Spencer, Canadian Nat., X. 1882, p. 1(55, nomen 

 nudum; Trans, Acad. Sci. St. Louis, IV, 1884, pp. 564, .580, pi. 4, fig. 3; 

 Bull. Mus. Univ. State Missouri, I, 1884, pp. 14, 30, pi. 4, fig. 3. 



Calyptograpsus radiatus Gurley, Journ. Geol., IV, 1896, pp. 93, 308. 



The original description is as follows : 



Frond ellipsoid, but cyathiform in its growing state. Numerous delicate 

 branches, with two or three bifurcations, radiating from a 

 common i-adicle. Some of these touch or overlie each other, 

 but they are quite unconnected. The te.\ture is corneous, 

 with the surface striated and marked with minute depres- 

 sions or pits, which indicate the former position of the cel- 

 lule. These depressions are about the fourth of a millimeter 

 in diameter, with an equal space between. The branches are 

 about one-third of a millimeter broad. The greatest diame- 

 ter of the frond is less than 3 cm. Fragments of this species 

 so resemble species of CalJograptus that they could not 

 be readily distinguished; but in no si)eeies of the latter genus 

 is the conspicuous funnel form apparent. 



Formation and locality. — This fossil occurs in the " cherty beds" of the 

 Niagara dolomite at Hamilton, Ontario. 



Fig. .51. — I'ALYPTo- 



ORAPTf.S ? RADI- 



ATU.s Spencer. 

 Copy of Spen- 



CER'.S FIGURE. 



Subgenus RHIZOGRAPTTJS Spencer. 



RhizograpsuR Spencer, Canadian Nat., VIII, 1878, p. 460. — Gurley, Jonm. 



Geol., IV, 1896. pp. 101, 308. 

 Rhizograptus Lapworth, Quart. Journ. Geol. Soc. London, XXXVII, 1881, 



p. 176.— Spencer, Proc. Amer. Ass. Adv. Sci.. XXXI, 1883, p. 364; 



Trans. Acad. Sci. St. Louis, IV, 1884. pp. 562, 580; Bull. Mus. Univ. 



State Missouri, I, 1884, p. 30. — Miller, North Amer. Geol. and Pal., 



1889, p. 202. 



