16 Mr. W. H. Dall on certain 
Proader than in C. Rathbuni, and collectively about one half 
onger. 
Hab. Station 871, U.S. Fish Commission, lat. 40° 02! 
d4" N., long. 70° 23’ 40" W., in 115 fathoms muddy sand ; 
station 894, U.S. Fish Commission, lat. 39° 53’ N., long. 
70° 58’ 30" W., 365 fathoms mud and gravel, both in 1880; 
station 947, 312 fathoms, sandy mud, bottom-temperature 
44° F.; station 949, 794 miles south of Martha’s Vineyard, 
in 100 fathoms, yellow mud, bottom-temperature 52°, surface 
66° F.; station 997, 335 fathoms, yellow mud, bottom- 
temperature 40° I’.; these last in 1881 (Verrill) ; and from 
the same localities as C. Rathbuni in the West Indies (Agassiz), 
with the additional locality of station 264, 416 fathoms, grey 
ooze, off Grenada, bottom-temperature 42°°5 F.* It is named 
in honour of Dr. T. H. Bean, of the United-States Fish 
Commission. 
Family Addisoniide, Dall. 
Shell asymmetrical, porcellaneous, somewhat like Capulac- 
meea, Sars. 
Soft parts much as in the last family, but strongly asym- 
metrical, with an enormously developed lateral series of 
separately inserted gill-lamine, like those of Patellide, and 
without filamentary appendages of any kind. Radula with a 
large simple rhachidian tooth with, on each side, two large 
simple transverse laterals, followed by two minute ones, and 
a large outer lateral with a strong tridentate cusp, outside of 
which is a single scale-like flat uncinus, bearing an elongated 
thickened ridge, but no cusp. 
Formula: 
1 
1 G+242242+5 1 
This family might be incorporated with the last, were it not 
for the differences in the branchie and in its dentition. These — 
latter are of great weight. The dentition of Addzsonia is like 
nothing known in the whole group of Rhiphidoglossa, but, 
while it recalls the dentition of the Chitonide in some features, 
has a decidedly Docoglossate aspect. Perhaps the most 
rational hypothesis is that this group bears to the preceding 
family much such a relation as in Pulmonata is borne by the 
Cyclotacea of Troschel towards the Cyclostomacea. Indeed 
the resemblance of the radula of Cocculina Rathbun to that 
* This is, perhaps, the shell referred to under the name of “ demea 
rubella ?, Fabr.,” Verrill, Proc. U.S. Nat. Mus. iii. p. 891, dredged (dead) 
at station 894, United-States Fish Commission, 1880, off the S.E. coast 
of New England, in 39° 53' N., 70°58’ 30" W., in 365 fathoms, 
