C. E. Beecher — Restoration of Stylonurus Lacoanus. 147 



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), Hall 6 presented a note on 

 Stylonurus 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 description of this form, and Hall is not 

 mentioned. Hall further says: "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 Dolichocepliala Lacoana has priority over Stylo- 

 nurus 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 number of real things. Some statement, therefore, 

 should be given of the character and amount of the material 

 that has been collated to furnish a restoration of Stylonurus 

 Lacoanus. 



(1) The specimen of the cephalothorax described by Hall 

 shows the complete outline and upper surface of this part, and 

 a cast from the original was taken to represent this portion in 

 the restoration. (2) The type of -6'. Lacoanus Claypole in- 

 cludes a large part of the cephalothorax of an individual 

 nearly the same in size as the preceding. (3) Dr. J. M. Clarke 



