Om 
VOI 
it may be readily distinguished from the young of the fol- 
lowing species by the specific characters, which are the result 
of the examination of a vast number of individuals of each 
species. 
Sp. 2. MODIOLA PAPUANA. 
M. testa fusca (sub epidermide albida) ; latere postico ala 
rotundata ; latere antico distincte sinuato. 
Musculus papuanus. D'drgen. Conch. tab. 22, fi. c. 
Mytilus Modiolus. Linn. Syst. Nat. 1, 1158. 
Gmel. Syst. Nat. 1. 
Mont. Test. Brit. 1, 163—Supl. p.71. 
‘Modiola papuana. Lam. Syst. des Anim, sans. Fert. 113, 
TOL; 
Var. @. latere antico abrupte umbilicato. 
Mytilus umbilicatus. Penn. Brit. Zool. iv. 112, tab. 65. | 
Habitat in mari Mediterraneo et in oceano Europeo vul- 
garis. 
HORSE MODIOLE. 
Shell fuscous (beneath the epidermis whitish) ; hinder side 
with a rounded wing ; anterior side distinctly sinuated. 
This species is common in the European ocean and Me- 
diterranean sea. On our coast it is called the horse-muscle. 
It sometimes grows to the length of nine or ten inches, 
and is subject to great variation in colour, being found 
black, fuscous, and luteous, but beneath the epidermis the 
shell is invariably whitish. In the young state it has been 
considered as forming two species, which have been de- 
scribed by Pennant and Donovan under the names curtus 
and barbatus. The beard-like epidermis of the young shell 
ts simple, and not serrated, Pennant considered the umbi- 
