BRACHTOPODA. 193 



LIORHYNCHUS, Hall. 1860. 



PLATE LIX. 



1842. 0)-ms, AtryjM, Vanuxem. Geology of N. Y. ; Rept. Third Dist., p. 14fi, fig. S; p. 168, tig. 2; 



p. 182, fig. 2. 



1843. Atrypa, Hall. Geology of N. Y. ; Rept. Fourth Diwt., j). 182, tig. 11 ; p. 223, fig. 2, Tiiblea of 



Organic Remains, No. 67, fig. 1. 

 1855. Rhyncliondla, Shomakd. Rept. Geol. Surv. Missouri, p. 205. 

 1860. Leiorhynchus, Hall. Thirteenth Ann. Rept. N. Y. State Cab. Nat. Hist., pp. 75, 85, 80, 



figa. la, 6. 

 1860. Mliynckonellaf Billings. Canadian Journal, vol. v, p. 273, figs. 26-28. 

 1863. Rhynchonella? Billings. Geology of Canada, p. 384, fig.s. 418a-c. 



1866. Leiorhynchus. A. Winchell. Rept. Lower Peninsula of Michigan, p. 95. 



1867. Leiorhynchus, Hall. Palseontology of N. Y., vol. iv, pp. 855-364, pi. Ivi, figs. 1-49 ; pi. Ivii, 



figs. 1-29. 



1868. Rhynchonella, Meek. Trans. Chicago Acad. Sci., vol. i, p. 93, pi. xiii, figs. 9a-c. 



1873. Leiorhynchus, Hall and Wiutfield. Twenty-third Ann. Rept. N. Y. State Cab. Nat. Hist., 



p. 240, pi. xi, figs. 25-27. 



1874. Leiorhynchus, Nicholson. Geological Magazine, new ser., vol. i, p. 120. 



1884. Rhynchonella, Leiorhynchus, Walcott. Monogr. U. S. Geolog. Survey, vol. viii, p. 153, pi. xv, 



figs. 1-4 ; pp. 157-159, pi. xix, figs. 5, 9. 



1885. Leiorhynchus, Clarke. Bull. U. S. Geolog. Sui'v., No. 16, pp. 24, 31, 33, OS, pi. iii, tig. 14. 



1886. Rhynchonella, Ulkich. Contributions to American Palseontology, p. 26. 



1887. Liorhynclms, ffiHLERT. Fischer's Manuel de Conchyliologie, p. 1308. 



During the period of the predominance of the foregoing species of Camarotce- 

 CHiA in the middle Devonian, certain shells, not essentially varying from them 

 in internal structure, assumed a peculiar exterior expression, the fold and sinus 

 becoming strongly plicated, while the lateral slopes are covered with low, faint 

 or obsolescent duplicating ribs ; umbones smooth ; substance of the shell very 

 thin. To this group the term Liorhynchus* was applied in 1860, and the typical 

 species is the Orthis quadricostata, Vanuxem, of the Hamilton fsiunas. 



These shells constitute an interesting lateral line of development which was 

 continued from the later Devonian into the early faunas of the Carboniferous, 

 where it probably outlived its parental type. The species of the middle Devo- 

 nian seem to have flourished most abundantly in the bituminous sediments of 

 the Hamilton series. Thus in the Marcellus shales and limestones, shells of 



* Thirteenth Report New York State Cabinet of Natural History, p. 75. The original spelling of this 

 term was Leiokhynchlls ; as above given its orthography is probably less open to objection. The term is 

 retained for these fossils, although the word was earlier in use for a recent genus of Vermes {according to 

 Agassiz), or Coleoptera (according to Dall). What its value may be in this latter use we are not informed, 

 but at all events there is little danger of any confusion of intent in its application to groups so remotely 

 connected. 



