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MODIOLA. 
MyriLLus, auctorum. 
Moprota, Lamarck, Sowerby. 
CHARACTER GENERICUS. 
Testa bivalvis, subtransversa, inzquilatera; latere postico 
brevissimo umbo ad brevissimum latus incumbens. Cardo 
sepius edentulus. Fosswla ligamentalis linearis margi- 
nalis. Jmpressio muscularis unica. 
AMIMAL bissoferum. 
GENERIS DIVISIONES. 
* Cardo edentulus. 
a, Testa levis; latere postico aliformi. 
b. Testa longitudinaliter et oblique costato-striata; latere 
postico aliformi. 
c. Testa antice et postice costato-striata; latere postico 
rotundato. 
** Cardo dentatus. 
a. Testa levi; latere postico rotundato. 
b. Testa longitudinaliter aut oblique striata; latere postico 
aliformi. 
MODIOLE. 
GENERIC CHARACTER. 
Shell bivalve, nearly transverse, unequal-sided, the hinder 
side very short. Beak resting on the shortest side. 
Hinge generally edentulous. Ligamental excavation 
linear, marginal. Muscular impression one. 
ANIMAL furnished with a byssus. 
The above character, with little alteration, is extracted 
from a dissertation by Lamarck, who first separated this’ 
F 2 
