215 



byssal sinus is deeper and much more acute, making a trapezoidal 

 auricle. The cauda is much shorter in A. Tarentina and the wing 

 much more oblique. It most nearly resembles a Florida species, but 

 in that the byssal angle is obtuse, the auricle triangular, the cauda 

 shorter. 



D^=- Vol. v. 126, (February, 1855.) 



Pedioularia decussata. T. solida, variabilis, plerumque ovalis, 

 striis radiantibus et volventibus concinne decussata ; apice laterali, 

 obtuso: apertura crescentica ; labro incrassato admodum revoluto ; 

 columella recta, acuta, sulcata. 



Long, i ; lat. -| poll. Inhabits coast of Georgia, where it was 

 dredged in the Coast Survey at a depth of 400 fathoms. 



This genus was established by Swainson on a single species from 

 Sicily, P. Sicula, which Mr. Gray says had been described by 

 Philippi as Thyreus paradoxus. Its well-marked apex is on the left 

 side, as in Concholepas, which, in miniature, it greatly resembles, and 

 to which Mr. Gray thought it to be allied. I should rather approxi- 

 mate it, for its structure and habits, to Leptoconchus madreporarum, 

 Gould (Purpura monodonta, Quoy^). The shelf on the left is not 

 simply a partition, but a true columella, which, if broken across, 

 shows an entire volution within. There is always found a small 

 notch or canal at both extremities of this columella. 



Helix j^ruginosa [arrosa]. T. globoso-conica, solidula, umbili- 

 cata, indentata et minutissime granulata, coloribus rufo-olivaceis et 

 flavis variegata et fascia fusca cincta ; anfractibus 7 convexis : apertura 

 rotundato-ovata ; labro reflexo, incarnato ; fauce livida. 



Diam. If poll. ; axis, -| a ^ poll. Brought from San Francisco by 

 Dr. Bigelow. 



Has the general form and coloring ofi7. Townsendiana, Lea, and 

 the aperture of H. tudiculata, Binney. The former has a different 

 aperture, revolving strije, and is destitute of a band ; the latter is not 

 umbilicated ; and neither have a granulated surface. [The name first 

 given was preoccupied by Pfeiffer.] 



Helix infumata. T. magna, discoidea, biconvexa, ad periphe- 

 riam obtuse carinata, late umbilicata, supra infumata et rugis minutis 

 obliquis asperata, infra nigerrima, nitida et minutissime granu- 

 lata ; anfr. 6£ convexiusculis : apertura rhombnidea ; labro rufo, basi 

 reflexiusculo ; fauce serieea, lilacina, prope labrum fuscescente. 



Diam. li ; axis, -| poll. Brought from San Francisco by Dr. 

 Biyelow. 



Has about the form and color of H. plicata, Born, without its com- 

 plicated aperture. It might at first be mistaken for //. Nuttallii Lea, 

 but is distinguished by its lenticular form, smoky black color, and its 

 peculiar rasp-like and granulated surface. 



