162 NEW-YORK FAUNA — MOLLUSCA. 



GENUS PATELLOIDA. Quoy and Gaymard. 



Animal with gills composed of subtriangular lamella?, which arise from the bottom of a cavity 

 on the back of the neck, and project out on the right side of the neck. Shell shaped like 

 the preceding, but usually smaller, more thin, depressed and diaphanous. 



Patelloida testudinalis. 



PLATE IX. FIG. 196. 



Patella testudinalis. Mullek, Zooligia Danica Prod. p. 237. 



Patella amcena. Say, Journ. Acad. Nat. Sc. Vol. 2. p. 223. 



Patelloida amwna. Couthouy, Bost. Journ. Nat. Hist. Vol. 2, p. 171. 



P. testudinalis. Lea, Tr. Am. PhiL Soo. Vol. 7, p. 73. 



Lottia id. Gould, Invertebrate, of Mass. p. 153, fig. 12. 



Description. Shell oblong-oval, frequently with a calcareous deposit, under which we 

 observe numerous radiating lines, which are crossed by minute concentric wrinkles. Margin 

 entire, acute : apex behind the middle, and turning towards the short end. 



Color. Whitish or greenish white, with brownish radiating stripes crossed by lines of the 

 same ; occasionally uniform greenish or brownish. Within a large piceous brown spot under 

 the apex, with an outer concentric line, from which proceed short radiations to the margin. 



Length, 0-8- 1'5. Width, 0-5- 0" 8. 



This shell, which is found along our northern coast, is now determined to be identical 

 with the P. testudinalis of Europe. I follow Couthouy rather than Gould in adopting Patel- 

 loida, although it is not unobjectionable on the score of its derivation. I can scarcely under- 

 stand by what right of priority the name of Lottia should be retained, when the very ground- 

 work of the group was first displayed by Messrs. Quoy and Gaymard, and the characters of 

 Lottia were by its author confined to the shell alone. 



Patelloida alveus. 



PLATE IX. FIG. 19*. 



Patella alveus. Conrad, Jour. Acad. Nat. Sciences, Vol. 6, p. 267, pi, 2, fig. 20. 

 Patelloidea id. Couthouy, Bost. Journ. Nat. Hist. Vol. 2, p. 177. 



Lottia id. Gould, Invertebrata of Mass. p. 154, fig. 13. 



Description. Shell oblong, sublinear, elevated, thin, pellucid, with fine radiating striae, and 

 fine concentric lines : sides nearly straight ; apex not central, pointing to the short end. 



Color. Whitish, with reddish brown spots and lines, which are visible within : a pitchy 

 brown central spot within. 



Length, 0-3-0-5. Width, 0-2 - 0-3. 



