264 GINGLYMACONCHA. AZORIDZ. 
FAMILY IV. AZORIDA. 
Solen, ductorum. 
Shell rather elongate, compressed, equivalve, gaping ante- 
riorly and posteriorly. Umbones situated a very little be- 
fore the middle of the shell; ligament large, exterior and 
hinge-shaped ; hinge toothed. Respiratory tubes annulated, 
included in one common tube. Foot oval and very large. 
Branchiz produced almost to the distant extremity of the lower 
respiratory tube. 
The animals of this Family inhabit the sea, in deep water, 
especially on a sandy bottom. 
Synopsis Generum. 
Testz sublineares, anticé et posticé valdé 
hiantes. Cardo in utraque valva bidentatus 13. Azor. 
Teste ovales, antict et posticé paulim hian- 
tes. Cardo in valva sinistra unidentatus ; 
dente bifido ; in dextra bidentatus, dente 
postico emarginato ........ 14. GoBRzvs. 
Testze pablieaearee. anticé et poutia valde bi 
antes. Cardo in utraque valva bidentatus 15. ADAsrus. 
Genus 13. Azor. 
Shells somewhat linear, gaping much anteriorly and poste- 
riorly. Hinge with two teeth in each valve. 
AZOR ANTIQUATUS. 
Shells striated roughly concentrically, rounded before and 
behind, the under margin broadly excavated or sinuate, with 
an impression extending obliquely from the umbones to the 
lower margin. Epidermis white or luteous-brown, elevated 
into irregular striee, especially before and behind. Length two 
inches and a quarter; height one inch. 
Solen Cultellus, Penn. Brit. Zool. iv. 85. t. Ixvi. f. 25; Dzll. 
Desc. Cat. 61. 
