284 A. E. Verrill—Recent additions to the 
and separate in front, and raised from the back, leaving a 
cavity beneath for respiration. Blood vessels, commencing in 
the anterior part of the back, extend backward, forking and 
diverging, in the area enclosed by the lateral lobes. 
This genus differs from Placobrunchus and Elysia in having 
the lateral lobes united together posteriorly over the back, s0 
that the respiratory cavity partially enclosed by them is closed 
behind. 
Elysiella catulus V. Plate vit, figures 5, 5%, 
Placobranchus catulus Agassiz, MS3.; Gould, Invert. of Mass., 2nd ed., p. 256, 
pl. xvii, figs. 249, 250, 1870. 
and S$. I. Smith; New Haven, Conn., and Wood’s Hole, Mass, 
—S. L Smith. 
It often floats with the bottom of the foot at the surface of 
the water. 
Shell smooth, polished, diaphanous, almost glassy, long con! 
bi slightly curved toward the acute apex. 
Animal white; swimming organs obovate 
rounded, and bearing the slender tapering tentacles near the 
Length of shell -46; diameter -08 of an inch. : 
This species was taken among Salpe, off Gay Head, Marthas 
Vineyard, in the afternoon, Sept. 9th, 1871,—Dr. A. S. P. ack- 
ard and A. E. Verrill. 
Ensatella Americana (Gould sp.) 
Solen ensis of American authors, not of Linnzeus. 
In addition to the differences in the shells of the American 
and European species, noticed by Gould and others, there ate, 
apparently, still more marked differences in the soft es 
. . u 
with similar basal spots; alternating with the primary and sec 
