542 bulletin: museum of comparative zoology. 



and seems to be almost identical with Clarke's specimens, it will be 

 necessary to remove Ceraurus rarus to the genus Encrinurus. The 

 type of Encrinurus rarus (Walcott), is so small and fragmentary that 

 it may be impossible to decide whether or not it is the same as Encri- 

 nurus vannulus Clarke, so that, at least until new material is obtained, 

 it will be better not to unite the two species. 



Walcott's specimen is 3.5 mm. long," and the glabella is 3 mm. wide 

 at the anterior end, and 1.5 mm. wide at the posterior lobes. 



Formation and Locality. — Lower Trenton, Beloit, Wisconsin. 



Eoharpes pustulosus (Hall). 



Ceraurus f pustulosa Hall, Pal. N. Y., 1847, 1, p. 246, pi. 61, fig. 2a-h. 



Harpcs pustulosa Whitfield and Hovey, Bull. Amer. mus. nat. hist., 

 1898, 11, p. 68. 



The senior author has seen the type of this species in the American 

 Museum of Natural History and agrees with Whitfield and Hovey 

 that it belongs to the Harpedidae. Whether it is to be identified with 

 the widespread, though rare, Eoharpes ottawaensis cannot be deter- 

 mined until a more carefid revision of our American Harpedidae is 

 undertaken. 



Formation and Locality. — Hall reports the specimen as having 

 come from the upper part of the Black River limestone at W 7 atertown, 

 New York. 



Other species commonly listed as Ceraurus. 



Beside the above species, wrongly listed as Ceraurus, Vogdes's 

 Catalogue contains a number of other species which obviously do not 

 belong to the genus as now restricted. 



Cheirurus apollo Billings, may be an Anacheirurus, (not Pseudo- 

 sphaerexochus as has been supposed by Raymond) . Cheirurus glaucus 

 Billings, Ch. satyrus Billings, and Ch. perforator Billings, belong to 

 Nieszkowskia. Cheirurus vulcanus Billings, Ch. prolificus Billings, 

 and Ch. mereurius Billings, seem to belong to Pseudosphaerexochus. 

 Ceraurus niagarensis Hall, Ch. tarquinius Billings, Ch. nuperus Billings, 

 and Ceraurus hydei Weller, are species of Cheirurus, though the last 

 two show a curious parallel development in that they have a Ceraurus- 

 like pygidium. Cheirurus sol, though very imperfectly known, was 

 made the type of the genus Heliomera by Raymond. And lastly, 



