THE NAUTILUS. 77 



sharply curved than in the adult. A few of the forms figured 

 by Tryon suggest the second deciduous stage of other species. 



In the foregoing attributions I am indebted to the two plates 

 of Caecidae given in Tryon' s Manual of Conchology, Vol. 8. I 

 may remark that all the species referred to are Atlantic coast 

 forms, the west coast of Europe, the east coast of the United 

 States south of Cape Cod, Teneriffe, Florida, West Indies and 

 Brazil. 



EXPLANATION OF PLATE V. 



1. Caecum annulatum, Brown. 5. Caecum clarkii. Carpenter. 



2. Caecum cooperii, Smith. 6. Caecum nitidum, Stimpson. 



3. Caecum johnsoni, Winkley. 7. Meioceras sp. , Carpenter. 



4. Caecum auriculatum, de Folin. 



A EUROPEAN MOLLUSK, HELCION PELLUCIDUM, NEVER BEFORE 

 RECORDED IN AMERICA. 



BY EDWARD S. MORSE. 



In looking over the sand from Easton's Beach, Newport, con- 

 taining Caecum, I discovered a minute specimen of the beauti- 

 ful limpet Helcion pellucidum of Great Britain. It was not over 

 a millimeter in length. I first detected it by the opalescent 

 markings like iridescent glass. These markings appeared as 

 four irregular-shaped areas near the anterior margin. In my 

 paper on An Early Stage of Acmaea (Proc. B. S. N. H., Vol. 

 34, pp. 313-323), I became familiar with the protoconchs of 

 Acmaea testudinalis and A. alveus and they do not even remotely 

 resemble the young pellucidum. The shell is corneous, narrow- 

 ing slightly behind. Without the metallic markings it would 

 have suggested Helcion pellucidum, but with these iridescent 

 spots it was unmistakable. So far as I know this species has 

 never been found on this side of the Atlantic. Miss M. W. 

 Brooks discovered another European species, Homalogyra atomus 

 at Newport and Narragansett Pier. 



In the American Journal of Science, Vol. 20, 1880, Verrill in 

 a brief note records finding in the docks at Newport a European 

 species never before recorded as American, Truncatella truncatula. 



