CERATIOCARIS. 11 



1883. Ceratiocaris, Fr. Schmidt. ' Mem. Imp. Acad. Sci. St.-Petersb.,' ser. 7, 

 vol. xxxi, p. 84. 



883. — T. R. J. and H. W. « Report Brit. Assoc, for 1883,' p. 217. 



884. — 0. B. Beecher. " Ceratiocaridse Upper-Devonian Measures," 

 ' Second Geol. Surv. Pennsylvania, P.P.P.,' p. 2. 



884. — T. R. J. and H. W. " Second Report on Palasoz. Phyllop.," 



' Report Brit. Assoc, for 1884,' p. 95. 



884. — T. R. J. and H. W. < Geol. Mag.,' dec. 3, vol. i, pp. 356, 396. 



885. — 0. Novak. ' Sitzungsb. k. bohm. Gesellsch. Wissensch.,' 

 Jahrg. 1885, p. 239. 



885. — T. R. J. and H. W. ' Third Report Pal. Phyll., Brit. Assoc. 



for 1885,' p. 334. 

 885. — H. Woodward. ' Geol. Mag.,' dec. 3, vol. ii, p. 349. 



885. — T. R. J. and H. W. Ibid., pp. 385 and 460. 



885. — J. M. Clarke. ' Geolog. Succession in Ontario Co., New 

 York,' pp. 18 and 20. 



886. — T. R. J. and H. W. ' Fourth Report Pal. Phyll, Brit. 

 Assoc, for 1886,' p. 229. 



886. — T. R. Jones. < Geol. Mag.,' dec. 3, vol. iii, p. 456. 



The generic characters of Ceratiocaris have been described by M'Coy, Salter, 

 H. Woodward, and Barrande in their several works and memoirs referred to above 

 and in the sequel. James Hall, R. P. Whitfield, A. S. Packard, J. M. Clarke, Fr. 

 Schmidt, C. E. Beecher, 0. Novak, and others have added much information, 

 general and special, on this and allied genera. The foregoing synonymy of the genus 

 supplies references to published observations on Ceratiocaris and some of its allies. 



We offer the following diagnosis of Ceratiocaris. Carapace bivalved, probably 

 with membranous attachment, no distinct hinge-joints being observable ; valves 

 subovate, semiovate, subquadrate, or trapezoidal; contracted in front, with the 

 end sharp or rounded above the median line of the valve ; more or less truncate 

 behind. Rostrum elliptical in shape, of a single lanceolate piece, chevron-marked. 

 Antenna? (?) obscure. Maxillae often apparent. Body many-jointed, with fourteen 

 or more segments, of which 4—7 extend beyond the carapace, ornamented with 

 delicate raised lines. Some or all of these segments bore small lamelliform 

 branchial appendages. 1 Last segment the longest, supporting three caudal spines, 

 namely : (1) a strong tapering telson (style), thick at the top or proximal end, usually 

 with a trilobed articulating surface (resembling that in the telson of Limulus), 

 pointed at the other, and more or less spinose, as shown by the bases of little 

 prickles ; and (2) two shorter, simpler, lateral appendages (stylets). The surface 



1 See the " Sixth Report on Fossil Crustacea," ' Brit. Assoc. Eep. for 1872,' p. 323. 



