438 MACTRID^!. 



published at Copenhagen in 1798, has removed all doubt 

 from my mind. It contains a full description of the 

 species in question, which was communicated by Muller 

 to his friend Fabricius ; and I now give it with all faults. 

 " Mya nitida. Long. 6. Lat. 3 lin. Testa extus in- 

 tusque glaberrima, pellucida, Isevis, nitida, absque striis 

 Candida, unicolor, subelliptica. Dens depressus obscu- 

 rior, quasi antrorsum nexus in quovis cardine. Telli- 

 nam prima facie revocat, at testa hiat, nee dentes tres, 

 nee alterum latus flexa est. In sinubus inter Christian- 

 sand et Arendal raro." The true teeth appear to have 

 escaped Miiller's observation ; and no wonder, for they 

 are exceedingly minute : what he called the ' ' dens " 

 must be the cartilage-pit. The Mya nitida of Fabricius 

 is Lyonsia Norvegica ; and it was in order to show the 

 difference between his and Miiller's shells of the same 

 name that he introduced the description quoted above. 

 I examined authentic specimens of Mulleins Mya nitida 

 in the collection of Fabricius at Copenhagen, and they 

 are decidedly the present species. Loven described it 

 as Syndosmya nitida. It appears to be the Scrobicu- 

 laria tennis of Philippi, a Panormitan fossil. 



3. S. AL'BA*,(Wood) 



Mactra alba, Wood, in Linn. Trans, vi. p. 165, t. xvi. f. 9-12. Syndosmya 

 alba, F. & H. i. p. 316, pi. xvii. f. 12-14. 



BODY whitish, with a pale tint of sky-blue interspersed with 

 flake -white spots : mantle thickened at its edges and fringed 

 with very small whitish papillae (according to Bouchard- 

 Chantereaux these papillae are arranged in three rows) : tubes 

 cylindrical, elastic in respect of both length and width ; when 

 fully extended they are as long as the shell is broad, and 

 sometimes distended to three times their usual diameter ; each 

 is covered with a light-brown epidermis, and when half ex- 



* White. 



