Professor C. E. Beecher — On Stylonurus Lacoanus. 483 



was based upon a second specimen found in Wyoming County, 

 Pennsylvania, which preserves about three-fourths of the cephalo- 

 thorax, and belonged to the collection of R. D. Lacoe, of Pittston. 

 This vp-as given the name Dolichocephala Lacoana, and rightly 

 classified with the Merostomata. It therefore appears that, up to 

 this time, the name Stylonurus excelsior was simply nomen nudum, 

 and as such cannot be recognized as valid. 



In 188-i Hall ' published his description and figure of the New 

 York specimen in the thirty-sixth Annual Report of the New York 

 State Museum, in a paper entitled " Description of a New Species 

 of Stylonurus from the Catskill Group."- It is here that the New 

 York specimen was first figured and a description given, and the 

 date of publication of this paper is the one to be considered in 

 deciding the claims of Stylonurus excelsior as Hall's species. 



At the Philadelphia meeting of the American Association for 

 the Advancement of Science, September, 1884 (Proc. A. A. A. S., 

 vol. xxxiii, published 1885), HalP presented a note on Stijlonurus 

 excelsior, merely referring to its occurrence, and citing Martin's 

 abstract with page and month of publication. This citation is 

 repeated by Hall in each of his notices of this species, for only by 

 thus establishing the species could he have any claim to priority. 

 As already mentioned, Martin's paper does not attempt any descrip- 

 tion of this form, and Hall is not mentioned. Hall further sa^'s: "The 

 carapace is described and figured in the 36th Report of the N.Y. 

 State Museum of Natural History," without reference to plate, page, 

 or year, and it is therefore quite possible that this description was 

 not published until after the meeting of the Association. In any 

 case, it appeared some months later than Claypole's paper, and the 

 name Dolichocephala Lacoana has priority over Stylonurus excelsior, 

 and must be recognized. 



Claypole failed to point out the affinities of this form with 

 Stylonurus, and proposed a new generic term for his species. 

 Although there are differences that may prove of generic value 

 when more complete specimens of the American species have been 

 studied, yet at the present time there seem to be no strong reasons 

 why the specimen in question should not be considered as belonging 

 to Stylonurus, and it is upon this ground that the present restoration 

 is attempted. 



Material available for a Restoration. 



Restorations of extinct organisms are largely exhibits of mental 

 architecture, based upon the personal interpretation of a certain 



' J. Hall, " Description of a New Species of Sf>/lo}uiri/s from the Catskill 

 Group" : Thirty-sixth Ann. Rep. N.Y. State Mus. Nat. Hist., 1884. 



- J. Hall & J. M. Clarke, " Trilobites and other Crustacea of the Oriskauy, 

 Upper Helderberg, Hamilton, Portage, Chemung, and Catskill Groups " : Geol. 

 Surv. of the State of New York, Pala;outology, vol. vii (1888). 



^ J. Hall, " Note on the Eurypteridiie of the Devonian and Carboniferous 

 Formations of Pennsylvania, with a supplementary note on titijloniivHs excclfior '" : 

 Proc. Am. Assoc. Adv. Sci., vol. xxxiii (188-3), Philadelphia Meeting (held 

 September, 1884). 



