168 IOWA GEOLOGICAL SURVEY 



Genus MACROPETALICHTHYS Norwood and Owen. 



This genus, certainly one of the most primitive of Arthrodires, 

 is represented in this country by the typical species, which was 

 first described under the name of M. rapheidolabis * Subse- 

 quently, two new specific titles, M. sullivanti and M . manni, were 

 proposed by Newberry for cranial shields that presented no 

 important differences from the type, and it was afterwards 

 proved that no constant distinctive features exist. Hence only 

 the name originally proposed for the type species is entitled 

 to recognition. The same author also pointed out that the so- 

 called Placothorax agassizii of Hermann von Meyer, published 

 at the same time as Norwood and Owen's description, and more 

 fully illustrated the following year, was founded upon a de- 

 nuded headshield of Macropetalichthys. The so-called "Phys- 

 ichthys" of von Meyer was also shown by Smith Woodward to 

 be a composite aggregation including fragments belonging to 

 Macropetalichthys, Rhynchodus and Pterichthys rlienanus.i A 

 review of the more recent literature of the genus has been given 

 by the writer in another place, and need not be repeated here.f 



Macropetalichthys rapheidolabis Norwood and Owen. 

 (Text-figure 24) 



1846. Macropetalichthys rapheidolabis Norwood and Owen, Amer. Journ. Sci. 

 ser. 2, 1, p. 371, text-figs. 1, 2. Also separate folio. 



1851. "Buckler of ganoid fish," L. Agassiz, Proc. Amer. Assoc. Adv. Sci. 



5, p. 179. 



1852. Macropetalichthys sp. J. S. Newberry, Annals of Sci. 1, p. 12. 

 1857. Agassichthys sullivanti J . S. Newberry, Bull. .Nat. Inst. p. 124. 

 1857. Agassichthys manni J. S. Newberry, Bull. Nat. Inst. p. 122, woodcut. 

 1862. Macropetalichthys manni and M. rapheidolabis J. S. Newberry, Amer. 



Journ. Sci. ser. 2, 34, pp. 75, 76, woodcut. 

 1873. Macropetalichthys sullivanti J. S. Newberry, Rept. Ohio Geol. Surv., 

 Pakeont. 1, pt. 2, p. 294, pi. 24, 25, fig. 1. 



1889. Macropetalichthys sullivanti J. S. Newberry, Monogr. TJ. S. Geol. Surv. 



16, p. 44, pi. 38, figs. 1, 2. 



1890. Macropetalichthys sullivanti E. D. Cope, Amer. Nat. 24, p. 846. 



*Amer. Journ. Sci. 1846, ser. 2, 1, pp. 367-72. Also a separate abstract in folio, 

 published at Madison, Iowa, under date of February 16, 1846, a copy of which is 

 preserved in the library of the Museum of Comparative Zoologv at Cambridge (ex 

 bill. N. S. Shaler). 



t Woodward, A. S., Vertebrate Paleontology in some American and Canadian 

 Museums. Geol. Mag. 1890, Dec. 3, 7, p. 459; also Cat. Fose. Fishes Brit. Mus. 

 1891, pt. 2, p. 303. 



JMem. N. Y. State Mus. 1907, 10, pp. 100-103. 



