252 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 65. 



XIRONOGITON INSTABILIUS (Moore). 



Plate 13, figs. 1 and 3. 



BrancMoMclla insiahilia Mooee, Proc. Acad. Nat. Sci. Phila., vol. 45, pp. 

 425-427, pi. 12, figs. 3a, 36, 3c, and 3e, 1893 (Wautauga County, North 

 Carolina, and Delaware County, Pennsylvania). — Smallwood, Biol. Bull., 

 vol. 11, No. 2, pp. 100-110, fig. 1, 1906 (Lake Clear, Harrietstovru, Frank- 

 lin County, New York). 



Specimem.—Tv^elve (8=Cat. No. 17643, U.S.N.M.), Stoney Man 

 Mountain, Virginia (Palmer and King), on Cambariis hartonii 

 (Fabricius); seven (6=Cat. No. 17644, U.S.N.M.), West branch of 

 Glennark Creek, North Eose, New York (A. C. Weed), on Cambarus 

 hartonii rohustus (Hay) ; six (5=:Cat. No. 17645, U.S.N.M.), Trubies 

 Run, a tributary of the Buckhannon Eiver, 7 miles above Biick- 

 hannon. West Virginia, August 4, 1899 (U.S.F.C), on Cambm^s 

 ohscurus Hagen ; six. Blowing Eock, Wautauga County, North Caro- 

 lina, 1893 (J. P. Moore), on Camharus hartonii (Fabricius) ; three 

 (2=Cat. No. 17646, U.S.N.M.), Chenowith Creek between Beverly 

 and Elkins, West Virginia, July 4, 1899 (U.S.F.C), on Camharus 

 hartonii carinirostris Hay; two (Cat. No. 17647, U.S.N.M.), Cheat 

 Bridge, Eandolph County, July 24, 1899 (U.S.F.C), on Camharus 

 hartonii carinirostris Hay; two (Cat. No. 17648, U.S.N.M.), Eight 

 Hand Fork of Chenowith Creek, a tributary of the Cheat Eiver, 

 Queens, West Virginia (U.S.F.C), on Camharus ohscurus Hagen; 

 two (Cat. No. 17649, U.S.N.M.), Elk Eiver at Cogars Mill, West 

 Virginia (U.S.F.C), on Camharus hartonii subspecies; one (Cat. No. 

 17650. U.S.N.M.), Cheat Eiver, near the Pike, West Virginia, July 

 25, 1899 (U.S.F.C), on Camharus hartonii carinirostris Hay. 



The dental formula of this species varies from 4-4 to 5-5 as shown 

 by the table below, compiled from the specimens examined. The 

 teeth of this species as described by Moore are 4-4, the original 

 description stating that, " the dark brown jaws are provided with 

 four strong, curved, conical teeth, which diverge slightly; the outer 

 pair are symmetrical, the left tooth of the middle pair is much 

 larger than the right; this being the case in both jaws in nearlj^ all 

 of the many specimens examined."^ Through the kindness of Pro- 

 fessor Moore the writer received seven specimens of this species col- 

 lected by him at Blowing Eock, North Carolina, in 1893. The 

 jaws of three of these worms have 4-4 teeth as described by Moore; 

 two other specimens have jaws of the 5^ type and are similar to 

 many specimens found in the United States National Museum col- 

 lections ; and the teeth of the other two could not be counted. 



iProc. Acad. Nat Sci. Phila., vol. 45, 1893, pp. 425-426, 



