12 



"The following are the reasons which I previously 

 held and still advocate : First — to raantain Cryptony- 

 jnus as a genus for several Russian and Swedish trilo- 

 bites, according to Angelin's diagnosis, which was de- 

 rived from ray short, but distinct, description given in 

 my work on the Silurian System of Esthland. 



"Second — To acknowledge the Zeih^is, Pander, only as 

 a genus for the Z. uniplicatus. This is the typical species 

 given by its author : we have no authority to take this 

 species, which differs from all other trilobites, and -class 

 it under Zethus verrucosus, which was doubtfully re- 

 ferred to this genus by Pander, and by this combination 

 establish an independent genus. 



"Third — The Zethus verrucosus, Fand., is probably the 



Crypt, verrucosus of Angelin ; not Grypt. parallelus, 



Eichw., or Oybele bellatula, Loven. The Z. bellatulus, 



Volb., is a synonym of Grypt. Woerthii, and not of Gal. 



punctata, Dalra., or variolaris, Broiigniart." 



Doctor Volborth advocates the priority of the genus 

 Zethus over that of Gryptonymus, in an article published 

 in the Bull, de I'Acad. des Scien., de St. Petersburg, vol. 

 xiii, No. 19, 1855. 



Dr. Shumard describes, in the Geological Survey of 

 Missouri, 1855, p. 198, pi. b, fig. 10, Encrlnurvs 

 deltoideus. 



In 1857, Nieszkowski, in his Monograph of the Tri- 

 lobites found in the Silurian System of the Baltic Prov- 

 inces, on p. 72-103, descriljes the genera Encrinuru^ 

 and Zethus. This author correctly figures and describes 

 the facial angle of Encrin. punctatus, and the follow- 

 ing species .• E. punctatus, pi. iii, fig. 6-7 ; E, multueg- 



