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GINGLYMACONCHA. PHOLADIDZ. 2 
Genus 1. PHOLAS. 
Pholas, ductorum. 
Shell oblong below, archedly notched, gaping behind; the 
reflected part hollow below and cancellated ; the hollows be- 
tween the cancelli terminating in perforations ; the accessory 
shells four ; two, one on the right, the other on the left, cover 
the anterior abductor muscle; the third is placed behind the 
umbones ; the fourth is attached to the dorsal membrane. 
This genus is distinguished from all the other British ones 
of the family by the cancelli terminating in perforations. 
Puowas Dacty.vs. 
Shell white, cancellated, the cancelli muricated, especially 
anteriorly, but not at all behind. 
The animal and its tracheal tubes white, spotted with pale 
bluish black ; the foot saffron colour ; the tracheal tubes spot- 
ted with blood-red. Length nine inches; breadth two and a 
half. 
Pholas Dactylus, Rond. Test. xxii. f. 2; Linné, Faun. Suec. 
2124; Syst. Nat. 515. no. 2124; Gmel. Syst. Nat. 3214. 
no. 1; Penn. Brit. Zool. iv. 76. t. exvui. f. 10; Pol, Test. 
1. 40. t. vii. f. 1. ad 11; Donov. Brit. Shells, t. exviu. ; 
Mont. Test. Brit. 20; M. & R. Trans. Linn. Soc. viii. 30 ; 
Flem. Edinb. Encycl. vii. 100; Dill. Desc. Cat. 35; Turt. 
Conch. Dict. 143; Lam. Hist. Nat. des Anim. sans Vert. 
v. 444, 
Pholas muricatus, Da Costa, Brit. Conch. 144. t. xvi. f. 2. 
Pholas hians, Pulé. Cat. Dorset. 26. t. iu. f. 2. 
Hypogeea verrucosa, Poli, Test. i. 43. t. vin. f. 1-11. 
Animal et tubi albi czeruleo-nigro pallido maculati; pede 
pallide croceo; tubis trachealibus apice sanguineo macu- 
latis. 
Habitat in marmore, creta et ligno frequenter. 
Pholas Dactylus inhabits the shores of the European ocean ; 
on our coasts, especially in the chalky districts, it occurs in 
great abundance; it perforates marble, wood, sandstone and 
