MoLLUSCA.j 
NATURAL HISTORY. 
477 
15. Pectunculus radians ? Lam. Hist. vi. 54. 
16. Arca Scapha, Lam. Hist. vi. 42. 
Icon. Chemn. vii. 201. t. 55. f. 54S. Ency, Mctli. pi. 306. 
f. 1, a, b. 
17. Mytilus erosus, Lam. Hist. vi. pt. i. 120. 
This shell was described by Lamarck from some New Holland 
specimens, that were probably collected by Peron in Baudin’s 
voyag-e. It is remarkable for being- very thick and solid, and of a 
fine dark colour, with only a narrow white band on the anterior 
basal edg-e. The edg;e is crenated, and the muscular impressions 
are very distinct, and raised above the surface, particularly that on 
the anterior valve, which is both pellucid and tubercular. 
IS. Modiola (Tulipa?) Australis, Nob. 
Modiola tulipa, var. 1. Lam. Hist. vi. pt. i. 111. 
This Australian species will most probably prove to be distinct from 
the American kind ; but the specimen before me does not afford 
sufficient materials to separate it, since there is only one water- 
worn valve in the collection. It is not so distinctly rayed as 
M. tulipa, and the inside is entirely of a brilliant pearly purple, 
except near the anterior basal edge. 
19. Lithophagus caudatus, nob. 
Modiola caudigera, Lam. Hist. vi. pt. i. 116. 
Icon. Ency. Mcth. pi. 221. f. 8. a, b. 
20. Meleagrina albida, var. a. La7n. Hist. vi. pt. i. 152. 
This appears to be a distinct species from those found in the Gulf 
of Mexico and the West Indies, but the difference is not easy to 
describe. The specimens before me, which are small, differ mate- 
rially from some of the same size among the American species. 
The outside is of a dull greenish-purple colour, with a few distant 
membranaceous laminae which are only slightly lobed, and not ex- 
tended into long processes like those of Avicula radiata (Zool. 
Misc. 1. t. 43.) which is the young of the American kind. The 
internal pearly coat has a bright yellow tinge. 
