and Shells of Massachusetts Bay. 87 
convex, semi-transparent, exterior of an uniform pure 
white, having numerous, minute, radiating ribs, traversed 
by equally fine concentric striations, which render them 
slightly scabrous, and give the whole surface, when 
viewed under a lens, a reticulated or clathrate appear- 
ance, similar to that of certain Fissurelle ; summit sub- 
central, margin feebly crenulated by the termination of 
the coste ; internal color a brilliant white. 
OssERvaTiONs. This beautiful little shell, which, by 
its coloration and the curious reticulation it exhibits 
when examined with a microscope, is very distinct from 
any known Patella, was procured from a cod caught 
abreast of Barnstable, last July. Only a single speci- 
men was met with, which has the appearance of being 
yetimmature. There can be no question, however, that 
the characters exhibited by it, would be still more con- 
spicuous in the adult stage. 
Riwvuna Noacuriwa, Lin. 
Synonyms and References. 
Patélla Noachina, Lan. Lin. Mant. p. 551. 
apertura, Mont. Test. Brit. pl. 13, fig. 10. 
fissurélla, GMEL. p. 3728, no. 193. 
Fissurélla Noachina, LxEnr, Des Hayes contin. of 
Lamarck—ed. 1836, no. 30. 
Sipho radiata, Brown, Illus. Conch. British Islands, 
pl. 36, fig. 20. - 
This singular little shell, upon which hardly any two 
authors appear to agree, as to genus and species, was 
