a37 



MONOGR.VPH OF THE GENUS 



LINGULA, Brug. 



By G. B. SowEUBY, E.L.S., etc. 



Char Gen. Testa tenuis, subfeqiuvalvis, fequilateralis, ovato- 

 elont a c pressa, apice subtmncato, basi subacuta, pediculo 

 affiS Cressiones musevdares in utraqne valv. quatuor, ad 

 iitnimciue latus dufe, altera basalis, altera subcentralis. 

 "latolconsis&g tor the most !«' <> ^ '^ -'fce: 

 Un«l with a small quantity of calcareous matter witlmi, its gene 

 rfom when the valvei are closed is au elongated oval, com- 

 ^essed and much resembhng a duck's bJl, (whence the specJic 

 Sation of the fcst knowir species) . The two valves arc very 



Sr^.d, the dorsal being --^'-'/l^f » -J^j:"; 



T,n+Prl nt tbe base When m a state of rest, the t^^o \aives are 

 rlted at the e^^^ in all parts. There is neither hgament nor 

 ^le t two vakes being held together by the adductor muse es 

 Musciilar ir^pressions several in each valve, arranged ni pan-s one 

 "ri "Lral, another toward the I-terio^ F^, a^^^^^^^^^^^^^^ 

 small and double, close to the posterior apex. The shcU is attaclieci 

 bv a peduncle which is fixed within the apex o the dorsil udve 

 ^Of^recenrspecies seven are here described and hgm-ed more 

 th^f doubie tU number are known in a fossil state, as charac- 

 terizing the various secondary and tertiary deposites. 



DESCRIPTIONS. 



1 LiNGULA ANATiNA (pi. Lxvii. f. 1, 2, 3, 9, 10.) Lam. 

 L testa oblonga, compressa, longitudinabtex substriata, apicis 

 ba^scit vdvaru^u'latitudine eequdi, apice subtrilobo, vulva ^en. 



^^'^^^^S^tS'^ ^ongitndiuaU, equal 



