THE NAUTILUS. 49 



A KADIODISCUS FROM BOGOTA, COLOMBIA. 



BY H. A. PILSBRY. 



Among a few shell received by Dr. Bryant Walker from Sefior 

 H no - Apolinor Maria there is a species of Radiodiscus which may 

 be defines as follows. 



RADIODISCUS MARIJS n. sp. 



The shell is closely similar to R. millecostatus, from which it 

 differs by the narrower umbilicus and by the perceptibly greater 

 height of the last whorl. The sculpture is essentially similar 

 except that the riblets are noticeably lower as seen where they 

 pass over the periphery, and the interstitial sculpture of delicate 

 striae parallel to the riblets and fine spiral lines, is also less dis- 

 tinct, though present. 



Alt, 1, diam. 1.85 mm.; width of umbilicus nearly 0.5 mm. 

 Riblets about 21 to one mm. at the periphery. 



R. herrmanni (Pfr.), R. orizabensis (Pils.) and R. pata- 

 gonica (Suter) differ in sculpture. I have not seen the fol- 

 lowing species, which from the descriptions appear to belong 

 to Radiodiscus: Helix coppingeri and H. magellanicus E. A. 

 Smith, Patagonia; Helix corticaria, H. muscicola, H. ~bryo- 

 phila, H. exigua, H. hypophlcca, all of Philippi, Malak. Bl., 

 1856, Chile. 



NOMENCLATORIAL NOTES. 



BY W. H. DALL. 



In 1838 Sowerby figured in the Conchological Illustrations 

 and described in his Malacologies 1 Magazine an Arctic shell under 

 the name of Margarita acuminata. In 1842 Mighels and Adams 

 in the Boston Journal of Natural History identified and figured 

 a Margarita from the Gulf of St. Lawrence under Sowerby 's 

 name, at the same time pointing out (as has every subsequent 

 author) certain discrepancies between the two. Owing perhaps 

 to the rarity of the shell, which has been well figured by Morse 



