No. 399.] WORTH-AMERICAN INVERTEBRATES. 209 
1898. CALMAN, W. T. On a Collection of Crustacea from Puget Sound. 
Ann. New York Acad. Sci. Vol. xi, No. 13, pp. 274-282. 
1899. RICHARDSON, HARRIET. Key to the Isopods of the Pacific Coast 
of North America, with Descriptions of Twenty-two New Species. 
Proc. U. S. Nat. Mus. Vol. xxi, pp. 815-8 
1900. RICHARDSON, HARRIET. Key to the Isopoda of the Atlantic Coast 
of North America, with Descriptions of New Species. (In manu- 
script, to be published later.) 
In addition to those mentioned, the works of G. O. Sars, 
H. J. Hansen, Schicedte and Meinert, Stebbing and Budde- 
Lund, have been of much assistance in the compilation of this 
key. 
SYNOPSIS OF THE ISOPODA. 
a. Legs of the first pair cheliform. Uropoda terminal. Pleopoda, when 
distinctly developed, exclusively natatory. . . . . I. CHELIFERA 
4'. Legs of the first pair not cheliform. 
4, Uropoda lateral. 
c. Uropoda forming together with the terminal segment of the 
Decr a caudal fan. Pleopoda for the most part 
natatory. . II. FLABELLIFERA 
e whats valvedikc, deflated: Michi over the pleopoda, 
which, to a great extent, are branchial. III. VALVIFERA 
&. Uropoda terminal. 
c. Free forms. 
d. Pleopoda exclusively branchial, generally covered by a 
thin opercular plate (the modified first pair). 
IV. ASELLOTA 
dŒ. Pleopoda fitted for air-breathing. . V. ONISCOIDEA 
c. Parasitic forms. Pleopoda, when present, exclusively bran- 
chial in the adult form, and not covered by any operculum. 
VI. EPICARIDEA 
I. CHELIFERA. 
a. Body scarcely attenuated behind. Mandibles without palp. Anterior 
maxillae with only a single masticatory lobe and a one-jointed palp ; 
posterior ones quite rudimentary. Epignath of maxillipeds narrow 
Second pair of legs ambulatory in character. . Family I. Tanaide 
a’. Body narrow, produced, depressed. Mandibles with a three-jointed 
palp. Anterior maxilla with two masticatory lobes and a two-jointed 
palp ; posterior ones well developed and setose. Epignath of max- 
illipeds large, laminar, branchial in character. Superior antenna 
with two multi-articulate flagella. Second pair of legs with a large, 
broad, flat hand, for burrowing purposes. . Family II. Apséudide 
