122 PHOLADIDTE. 



PHOLADIDEA, Leach. 



Shell more or less globose or oblong, equivalve, inequi- 

 lateral, surface of valves similar to those of Pholas; their 

 beaks not covered by callosities ; accessory plates small. 

 Muscular impressions as in Pholas. Anterior extremity 

 open in the immature, but closed in the adult shell by a 

 thin papyraceous permanent shelly coat, with a small open- 

 ing centrally and anteriorly for the foot. Posterior ex- 

 tremity truncated and gaping, usually furnished with an 

 expanded coriaceous cup. 



Animal claviform ; the mantle closed in front, except 

 a small opening for the passage of a truncated sucker- 

 shaped foot. Siphonal tube long, terminating in a disk 

 surrounded by cirrhi, encircling the openings of the bran- 

 chial and anal siphons, each of which are also surrounded 

 by radiating cirrhi. 



The separation of the calyciferous Pliolades from their 

 allies of the last-described genus, was, we believe, first sug- 

 gested on conchological grounds, by Dr. Goodall to Dr, 

 Turton, who, in his " Conchological Dictionary," gives the 

 name of Pholadklea Loscomhiana to our British species. 

 In the thirty-ninth volume of the " Diction, des Sciences 

 Naturelles," the group is characterised under the name of 

 Pholadidea, and made a sub-genus of PJiolas. Swainson, 

 in his "Elements of Conchology'' (1835) called the genus 

 Pholidea, and in his more recent " Treatise on Malacology" 

 in Lardner's Cyclopedia, writes it Pholidaa, and refers to 

 Leach as the founder. 



The genus is a good one, seeing that both shell and ani- 

 mal afford excellent distinctive characters, which are pre- 



