136 KOCENE MOLLUSCA. 
6. Unio rumescens, Hdwards, MS. Tab. XX, fig. 17, a, 6. 
Spec. Char. U. testa transversd, irregulariter ovatd, tumidiusculd, valdé inequilaterali, 
levigatd ; pedi-regione convexd, siphoni-regione productd, subcuneatd ; umbonibus pro- 
minulis ; lunuld sub-excavaté; cardine angusto, dente cardinali obtuso, dente laterali 
elongato. 
Shell transverse, irregularly ovate or ovately wedge-shaped, somewhat tumid, very 
inequilateral ; pedal region rounded, siphonal region produced; umbones. slightly 
prominent and rugose ; lunule shallow ; cardinal teeth obtuse, lateral tooth elongated and 
narrow. 
Length, 1% weh. 
Locality. Weadon Hill (#dwards). 
A few specimens corresponding to the above characters are in Mr. Edwards’s cabinet, 
which he has considered to be distinct. J am unable to refer them to any published 
species. 
Unto Vectrensis, Hdwards, MS. Tab. XX, fig. 15. 
Spec. Char. U. testa obtuse ovatd, vel ovato-rotundatd, inflata, gibbosd, crassa, levi- 
gata; umbonibus magnis, sub-prominulis; pedi-regione rotundatd,  siphoni-regione 
oblique truncata vel obtuse angulatd ; margine dorsali convexiusculd ; margine ventrali sub- 
planatd. 
Shell obtusely ovate or ovately rounded, inflated, thick, smooth; beaks slightly pro- 
sminent ; pedilateral margin rounded, siphonilateral obliquely truncated or sloping and 
rounded ; pedal region one third the length of the shell; dorsal margin convex ; ventral 
margin slightly curved. 
Length, 1} inch; height, 1 inch. 
Locality. Weadon Hill, (Adwards). 
I have seen but one specimen, and this appears to be so very different in outline that 
with Mr. Edwards, I believe it to be quite distinct; I have therefore adopted the MS. 
name he has given to it. 
Tab. XX, f. 19, represents a specimen of this genus from Headon Hill which J cannot 
satisfactorily assign to any of the foregoing, or to any other species known to me; at the 
same time I am unwilling to consider it as entitled to a distinct specific position. 1 think 
it possible it may be a distortion, and until better specimens be found it must remain 
under the name of U. tumescens var. Headonensis. 
