LYONSIA. 31 



from the newer tertiaries of Sicily. Its foreign range 

 in a living state comprises the Sea of Ochotsk, and the 

 coasts of Iceland, Scandinavia, France, Italy, Algeria, 

 Greece, and Madeira, at depths varying from 10 to 70 f. 

 in northern, and from 4 to 70 f. in southern latitudes. 



Miss Hutchins is the reputed discoverer of this re- 

 markable and interesting shell. According to Clark 

 the gills consist of a single leaf on each side ; the tubes 

 appear to be enclosed in one sheath, which has the 

 margin finely dentated; and each orifice is garnished 

 with about eight white simple cirri, and as many black 

 equidistant points at their external edges. He has not 

 mentioned the filaments at the base of each tube. Such 

 discrepancies are extremely perplexing ; and if the iden- 

 tification of any species depended solely on characters 

 afforded by the soft parts, the study of conchology would 

 be almost impracticable. The faculty and means of 

 observation, as well as the good faith possessed by Mr. 

 Clark, were certainly not inferior to those which I have 

 exercised ; and yet how different is the result ! The 

 microscopic pustules covering the surface of the shell 

 appear to be the ends of the tubes which compose the 

 outer layer ; these are open in the young, and closed in 

 the adult. The inner layer is entirely nacreous. The 

 shells are occasionally found in the stomach of the red 

 gurnard. Dr. Lukis supposed that the young disguise 

 themselves in their sandy coating more completely than 

 the adult; but this is not always the case. The epi- 

 dermis is of a gelatinous or viscous nature, and thus 

 grains of sand as well as organic particles become 

 attached to it. 



It is the My a nitida of Fabricius (but not of Muller), 

 M. striata of Montagu, Amphidesma corbuloides of La- 

 marck, My a pellucida and Myatella Montagui of Brown, 



