VOL. XVI, -j PROCEEDINGS OF TPIE NATIONAL MUSEUM. 319 



1893. 



Three specimens, valves. Asceiisiou Island (Mus. jS^o. 125403). 

 The dentiferus of Kvauss is probably a variety of the Linnean species; 

 it has a somewhat aviculoid shape. 



7. Perna Chemnitziana Orbigny. 



Several specimens, Porto Grande (Mus. No. 125355). 



Variable in form, and perhaps connecting with the previous si^ecies. 



Family MYTILID^. 



Genu8 MYTILUS Liiin6. 



8. Mytilus edulis Linu^. 



One specimen, Cape Town; (Mus, No. 125370). 



A solitary example of small size, only 18 millimeters in length, of this 

 common and widely distributed form. 



9. Mytilus magellanicus Chemnitz. 



Several sp'jcimens. Cape Town (Mus. No. 125368). 



The shells collected at this place by the expedition that I have labeled 

 as above, upon comparison with examples of the same size from New 

 Zealand and Kerguelen Island, prove to be identical. The larger in- 

 dividuals measure 39 to 40 millimeters, from that to 9 millimeters or 

 less in length. 



10. Mytilus atropurpureus Dunker. 



Many fresh specimens, Fayal (Mus, No. 125300). 



These fine living exain])les show a rich purple seminacreous irides- 

 cence on the interior surface of the valves, unusually brilliant for ma- 

 rine mussels. 



* 11. Mytilus ovalis Lamarck. 



Several examples. Porto Grande (Mus. No. 125330). 



Genus LITHOPHAGUS Muhlfeldt. 

 12. Lithophagus aristatus Solander. 

 = L. caudir/era Lamarck. 



Two specimens. Porto Grande (Mus. No. 125,400). 



Genus DREISSENSIA Van Beneden. 



13. Dreissensia africana Van Ben. 



Numerous examples, living. Ashantee (Mus. No. 125334), 

 Many specimens of the ab(»ve, separate, and a large colony attached 

 to a twig, numbering probably as many as a hundred individuals. 



