CurLron.—Some New Zealand Amphipoda. 633 
body, the mouth-parts, and other appendages to — gibbosa, but 
in that species the fourth and fifth peraeopoda are not covered by the 
nie side-plate, and the fifth peraeopod, though ы than the fourth, 
"m the joints perfect. 
is evident that the genus Tetradeion must be placed in - family 
Stapotephalidea coming close to Phippsia Stebbing (= Aspidopleurus Sars). 
It represents a further development along the same line, but has rie fourth 
side-plate stil more largely developed and concealing the sixth and seventh, 
and in consequence peraepod 5 is very greatly reduce 
Detailed Description. io мй ooth, broad, and greatly swollen, side- 
plates of the first four а much deeper than their respective 
ents and мылын convex, so that the appendages of the head and 
peraeon and the whole of the pleon can be concealed from view when 
the animal is coiled up—the outline of the whole body then being ellipsoid. 
(Fig. 1.) 
/ 
Tetradeion crassum Chilton. 
Fic. 2.—First antenna. | Fic. 5.—Lower lip, with extremity 
magnified. 
Fie. 3.—Second antenna. - more highly ma: 
Fie. 4.—Mandible 
First side-plate subtriangular in outline, its posterior margin very 
convex; second strongly curved, narrow, only about one-fifth as wide 
as deep; t similar but less curved ; fourth enormously expanded, 
forming a quads convex serie E anterior margin nearly straight an 
the rounded posterior margin extending as far as the hinder end of third 
pleon stgmenk ; p side- аны. small, forming a small plate fitting into 
an emargination on upper margin of fourth; sixth and seventh not 
8 
of peraeon subequal in len h; first segment of pleon longer than 
second, third much shorter than second, lower margins of all three convex 
