new Species of Marine Shells. 183 
picked up in July at the eastern end of Nahant Beach. 
I have named this shell :after our. associate, Dr. A. A. 
Gould, as a slight tribute of acknowledgment of my re- 
peated obligations to him, for his assistance and coópe- 
ration in determining the identity of such species as I 
have supposed to be new, and the beautiful and accu- 
rate manner in which most of them have been delineated 
by him. 
cu 
PLEUROTOMA DECUSSATA. 
Plate IV. fig. 8. 
PI: testa parvulA, ovali, fusiformi, albidà, anfractibus quinque ue 
vexis, longitudinaliter plicatis, transverse striis frequentibus tenui 
decussatis, aperturà titngétooyals: basi sub-canaliculata, labro ses 
levi, superné indentato, columella nitida, depressà, arcu Rite d d basim 
sinistrorsum 'divergens. — rudis. 
‘Description. Shell gill oval, buio, viie, 
covered with a thin, light-ólivaceous adherent epidermis ; 
composed of five or six convex volutions, having the 
sutures strongly marked, piódue longitudinally and 
obliquely and decussated by frumerous delicate, revol 
ving strie ; the body whorl is rather ventricose, and 
constitutes a little more than half the entire length of the 
shell ; the revolving strie are more distinctly marked on 
this part than any other, but the longitudinal plaits dis- 
appear about half way between the suture and the base ; 
the other whorls are plicate in their whole extent ; ihe 
spire is obtusely conical; aperture elongated oval, 
- Slightly channeléd at the base ; lip thin, sharp, smooth 
internally, with a sub-angular sinus or indenture at its 
junction with the lower whorl; columella white and 
