BYRBHID^. 91 



NOSOTETOCUS MARCOVr. 



PI. X. figs. 4, 5. 



JS'osotetocm marcovi Scudd., Bull. U. S. Geol. Surv., No. 93. 17, pi. 2, figs 2,3 (1892). 



Florissant, Colorado. 



AMPHICYRTA Erichson. 



A North American genus witli only three species. A single fossil has 

 been found in Colorado. 



Amphicyrta inh^sa sp. nov. 



PL X, fig. 10. 



A single fairly well preserved specimen of a byrrhid from Florissant 

 seems referable to Amphicyrta. The form of the body is oval, broadest 

 posteriorly, and the size and general appearance not unlike A. clentipes Er. 

 of the Pacific coast. The head is rather narrow, aiad the labrum remark- 

 ably naiTow for its length, being scarcely transverse, with strongly rounded 

 front margin. A few joints of one of the antennae are seen crossing the 

 thorax, but present nothing peculiar. The elytra are sparsely and shallowly 

 punctate with circular puncta, removed from one another by at least double 

 their own diameters, and thus very closely resembling the sculpturing of 

 the elytra of A. clentipes if the puncta of the latter were slightly smaller 

 and more shallow. 



Length, 6.25 mm.; breadth, 5 mm., as preserved with partially expanded 

 elytra, but the probable actual breadth is 4.25 mm. 



Florissant, Colorado; one specimen, No. 11274. 



CYTILUS Erichson. 



A north temperate genus with very few species, of which two occur in 

 North America. Two fossil species are found in Colorado, and a recent 

 species is credited to the Bavarian Pleistocene. 



Cytilus tartarinus sp. nov. 



PI. X, fig. 6. 



Here I refer a single specimen of a byrrhid in which the hind tarsi are 

 plainly not retractile, but which does not agi-ee well with the characters of 



