2923 NEW YORK STATE MUSEUM 
Stylonurus (Ctenopterus) excelsior Hall 
Plates 47, 48 
Stylonurus excelsior (Stylomurus in error) Hall (Martin). N. Y. Acad. Sci. 
Trans. 1882. 2: 2 
Stylonurus excelsior Hall. N. Y. State Mus. 36th An. Rep’t. 1883. p. 77, 
pl. 5, fig. 1 | 
Dolichocephala lacoana Claypole. American Philosophical Soc. Proc. 
1883 21: 236, pl. 3 . 
Stylonurus excelsior Hall. American Assn. Adv. Sci. Proc. 1884. 33: 421 
“Stylonurus excelsior Hall & Clarke. Palaeontology of New York. 1888. 
7: 158, 221, pl. 26, 26A . 
Stylonurus lacoanus Beecher. American Jour. Sci. 1900. 10: 145, pl. 1 
Only two specimens of this species are yet known. One a natural ex- 
ternal mould of the complete carapace from the Catskill beds at Andes, 
Delaware co., N. Y., is in the possession of Rutgers College and is the type 
of Hall’s original description. Another fragmentary carapace from the same 
formation in Pennsylvania, the original of Claypole’s description, is now in 
the National Museum. Clarke succeeded in developing on the underside of 
the latter, a chelicera, one of the first pair of legs and the coxae of two 
legs of the succeeding pairs. | 
Both these specimens and the discovered appendages have been fully 
described by Hall and Clarke in Palaeontology of New York, volume 7, 
pages 158, 221, to which the reader is here referred for the details. 
Professor Beecher subsequently selected 5. excelsior for resto- 
ration on account of its gigantic dimensions, supplving the missing parts 
from the British species S. logani and 5S. powriei, and the 
American S. beecheri. The discovery by the authors of a specimen 
of S. cestrotus at Otisville retaining all save the first pair of legs, and 
the fact that S. excelsior is, according to the form and character 
of its carapace, manifestly more nearly related to that species than to any 
other, have suggested to us some corrections in this careful restoration which 
have already been dealt with in the preceding generic discussion. The 
