CONCHIFERA. 
439 
regular series, and somewhat hollowed for the reception of the 
ligament. 
Crenatula mytiloides .— The Muscle-Shaped Crenatula. 
Plate LXXXVIII. fig. 14. 
Ohlong-ovate, oblique ; the base acute; violet coloured, with 
obscure radiations. Inhabits the Red sea. 
TRIBE II.-MYTILACEA. 
Hinge with a subinterior marginal ligament, which is linear, 
very entire, and occupies a considerable portion of the anterior 
margin ; shell rarely foliaceous. 
Genus 27.—PINNA.— Linnaus. 
Generic Character. —Longitudinal, wedge-shaped, equivalve, 
gaping at the base, and pointed at the summit, with the beaks 
straight and acute; hinge lateral and without teeth ; ligament 
marginal, linear, very long, and half interior. 
Pinna inyens. — The Huge Pinna. 
Plate LXXXVIII. fig. 15. 
Nearly triangular, horn-coloured, smooth, with distant folia¬ 
tions ; striated on one side, with rough scaly wrinkles on the 
broader end. Twelve inches long. Inhabits the coast of 
Britain. 
Genus 28.—M YTIL US. — IAnnccus. 
Generic Character. —Longitudinal, equivalve ; apex acute, 
affixed by a byssus ; beaks acute, nearly straight and terminal ; 
hinge lateral, generally without teeth; ligament marginal, and 
partly internal; muscular impressions elongated, clavate, and 
sublateral. 
Section * Longitudinally furrowed. ** Without furrows. 
Mytilus edulis .— The Edible Mytilus, or Muscle. 
Plate LXXXVIII. fig. 16. 
Oblong-oval, nearly smooth, pointed and slightly carinated at 
the beak, truncated on one side, and dilated on the other ; cov¬ 
ered with an olivaceous epidermis; beneath which it is radiated 
