ww 
two Species of Patelloidea. 113 
luminous, disposed around the sides of the back, and ter- 
minate in a long canal or tübe, which, crossing the back 
of the neck from the left side, opens into the branchial 
sac, on the right side, at the base of the branchie. The 
liver is of a brownish color, and occupies nearly the 
whole of the central portion of the back. : The position 
of cm heart. was not pied ad 
Shell, as described by Mr. Say. Jour. rem e 
Sciences, vol. H. 223. 
OssrEnvATIONS. After the numerous genera, which, 
up to 1825, had been dismembered from the Linnean 
Pavélles; they were mppted to remain. so clearly de- 
n alts Mr. lisi had isiin "ue 
phonária, now fully admitted by all Zoblogists 
peared to be so thoroughly sifted, so uniform, and if i 
term may be used, homogeneous in their structure and 
appearance, that any farther dismemberment seemed 
absolutely impracticable. Messrs. Quoy and Gaimard, 
the able naturalists who accompanied the Astrolabe in - 
her scientific voyage, prosecuted under the auspices of 
the French government, have proved the contrary, by 
ascertaining that a number of Patelliform shells, the only 
external peculiarity of which, was that of being more 
symmetrical than the generality of Patelle, protected 
animals which, in all other respects closely resembling 
those of that genus, differed from them in the important 
character of having the respiratory organs composed of 
“a single branchia on the right side, formed by numerous 
— lamelle arranged above each other on each 
