14 



BULLETIN 65, UNITED STATES NATIONAL MUSEUM. 



Figs. 13-15. — 13, Callograptus minutus Spencer; 14, C. 



MULTICAULI.S SPENCER ; 15, C. N.IAGARENSIS SpE.N'CER. 



(After Spencer.) 



branches radiating from a couituou axis. In texture it is corneous, and the sur- 

 face of tbe numerous flattened branches is marked with striations, appearing 

 like oval impressions, while on the under side there are minute pits indicating 

 the apertures of the cells, as many as twenty pits being visible in one-fourth of 

 an inch. The fronds are usually less than 2 inches in breadth, and resemble 



15 the outline of a bush, 



where the branches 

 principally originate 

 from the root. 



This species is 

 e a s i 1 y distinguished 

 from DictijoiH'ina by 

 the bushlike foi-m and 

 more slender branches, 

 together with an 

 almost entire absence 

 of dissepiments a n d 

 cell markings. In tKe better preserved specimens the cells readily distinguish 

 it from Dendrograpsus, as also the more numerous and more parallel branches. 

 The branches are broader, more drooping, and further separated than in the 

 species of this genus found in the Quebec group. 



Formation and locality. — This species occurs in the Niagara dolomites and 

 shales at Hamilton, Ontario. 



Gurley notes the following concerning the species, which is known 

 only from the type, now destroyed : 



The description of 1SS4 contains several statements requiring separate notice. 

 The pits indicating the thecal apertures are stated to be " as many as 12 in a 

 centimeter," a number amounting to 30 in an inch (25 mm.), as contrasted with 

 SO. The longer diameter of the aperture is about 0.5 mm. 



The frond does not usually exceed 4 cm. in breadth, being broader than high. 

 The branches are a little less than 0.5 mm. broad, with spaces between them 

 sometimes exceeding 1 mm. 



CALLOGRAPTUS MINUTUS Spencer. 

 Text figure 13. 



Callograpt'is minutus Spencer, Canadian >s'at., X, 1SS2, p. 1G5, nomen 

 nudum; Trans. Acad. Sci. St. Louis, IV, 1884, pp. 564, 572, pi. 1, fig. 12; 

 Bull. Mus. Univ. State Missouri, I, 1884, pp. 14, 22, pi. 1, fig. 12.— 

 Gurley, Journ. Geol., IV, 1S9G. pp. 93, 308. 



The original description is as follows : 



Frond orbicular. Branches, with one or two bifurcations, regularly diverging 

 from the initial point like the venations of a palm leaf; they are all free. The 

 surfaces are striated. The bi'anches do not exceed one-fifth of a millimeter in 

 breadth and are about half a millimeter ai)art. The whole height of the frond 

 is a centimeter and the greatest breadth somewhat less. 



Formation and locality. — This species occurs in the Niagara dolomite at 

 Hamilton, Ontario. 



