GINGLYMACONCHA. PHOLADID. 253 
Conch. Dict. 146; Lam. Hist. Nat. des Anim. sans Vert. 
v. 445. 
Pholas bifrons, Da Costa, Brit. Conch. 242. t. xv. f. 4. 
Pholas parvus, Donov. Brit. Shells, t. xix. Testa junior. 
This species is extremely common on most of our chalky 
coasts, and is equally so in Scotland, where it is found in bitu- 
minous slate and hard clay. Length three inches and a half ; 
height one inch and three quarters. 
Genus 3. ANCHOMASA. 
The shells oblong, with a rounded notch anteriorly below, 
gaping behind; the reflected part of each valve hollow beneath 
and simple: there is but one accessory shell, which covers the 
anterior adductor muscle entirely : between the umbones is an 
abrupt obtuse process in each valve. 
ANCHOMASA PENNANTIANA. 
Shells smooth posteriorly ; behind the middle slightly, before 
the middle strongly cancellated; the angles of the cancelli 
pointed ; the epidermis white or pale testaceous. 
Pholas parva, Penn. Brit. Zool. iv. 77. t. xl. f. 13; Mont. 
Test. Brit. 22. t.i.f. 7,8; Flem. Edinb. Encycl. vii. 100 ; 
Dill. Desc. Cat. 38; M. & R. Trans. Linn. Soc. vii. 33 ; 
Turt. Conch. Dict. 142 ; Wood, Gen. Conch. 1. 82; Turt. 
Conch. Dict. 143. 
Pholas Dactyloides, Lam. Hist. Nat. des Anim. sans Vert. v. 
445. 
This species is very common in the Kingsbridge Estuary, 
where it perforates wood: it has been found at Torbay and in 
other parts of the western coasts ; but I have myself found it 
larger and more abundant in the clay-slate rocks on the coast 
of Sussex near Hastings. Length two inches ; height three- 
quarters of an inch. 
The abdomen is pale bluish-black ; the tracheal tubes fuscous, 
their extremities ciliated with pale violet. 
