380 NEW YORK STATE MUSEUM 



G los s ograp t us ciliatus Hopkinson & Lapworth. Geol. Soc. Quar. Jour. 1875. 



31:659 ; pi. 34, fig. 7 

 G lossograp t us spinulosus Lapworth. Ann. Mag. Xat. Hist. 1880. 5:283 

 Diplograptus ciliatus Walcott. Alb. Inst. Trans. v. 10, 1881. (Advance 



sheet. 1879. p. 34) 

 Diplograptus spinulosus Walcott. Ibid. p. 3 5 

 Glossograptus ciliatus Lapworth. Roy. Soc. Can. Trans. 1887. v. 5, sec. 4, 



p. 184 

 Glossograptus ciliatus Lapworth. Can. Geol. Sur. Rcp't. Ser. 2. 1889. v. 3, 



pt i, p. 95 B 

 Glossograptus ciliatus Ami. Geol. Sur. Can. Rep't. Ser. 2. 1889. v. 3, 



pt 2, p.117 K 

 Glossograptus spinulosus Dodge. Am. Jour. Sci. 1890. 40:153 

 Diplograptus spinulosus Walcott. Geol. Soc. Bui. 1890. 1:339 

 Glossograptus ciliatus Gurley. Geol. Sur. Ark. An. Rep't. 1892. 3:404! 

 Glossograptus spinulosus Gurley. Ibid. p. 4 1 1 

 Glossograptus ciliatus Gurley. Jour. Geol. 1896. 4:299 

 Glossograptus spinulosus Gurlsy. Ibid. p. 299 



Description. Synrhabdosome not observed. Rhabdosome prismatic 

 with subhexagonal section, attaining a length of 25+ mm [see " Remarks" 

 and a width of 1.6 mm on the frontal sides and the double width on the 

 lateral faces (often double that width again in obliquely compressed speci- 

 mens, see below). Sicular extremity rounded, furnished with four short, 

 straight sicular spines (1.2 mm long) which are directed downward and two 

 longer horizontal lateral spines. Lateral faces smooth, bearing along the 

 median line a row of straight spines ( 1.4 mm long), which are directed 

 upward at an angle of 40 and correspond to every second tinea. Sicula 

 large (3.3 mm), plump, with four apertural spines that are connected by a 

 strong apertural ring [fig. 331]. Thecae broad and low (ratio 2:1), rec- 

 tangular in section, inclined at an angle of 30", overlapping three fourths 

 their length, numbering ii in 10 mm with little variation. Apertures rec- 

 tangular, lower and upper margins straight, lateral margins concave ; each 

 protected by two long curved spines (3 mm long, but 2 mm ot which are 



