of the Pacific Shores of North America. 503 
PALEMON HETEROCHIRUS. Wiegmann. 
Palemon heterochirus, WiEGMANN ; Archiv für Naturgeschichte, 1836, i. 149. 
This is another of the large fresh-water shrimps of 
Mexico. They frequently attain a length of two feet, in- 
cluding that of the chelopoda, which are at least as long as 
the body. 
Mus. Berlin. 
STOMAPODA. 
SQUILLA DESAUSSUREI. Stimpson. 
Squilla scabricauda, Desaussure, (non Larr.) Rev. et Mag. de Zodl. v. 367. 
Hab. Mazatlan, ( Verreaux.) 
Mus. of M. Verreaux, Paris. 
ISOPODA. 
IDOTEA CONSOLIDATA. Stimpson. 
Idotza consolidata, STIMPSON ; Proc. Col. Acad. Nat. Sci. i. 89. 
Body convex, broadest at the fourth thoracic segment. 
First. four segments of thorax larger in every dimension 
than the last three, each bearing an umbo near the lateral 
gin, which is turned up a little. A sharp, slightly 
elevated transverse ridge across the thorax on each segment 
near its Posterior margin. No distinct epimeral sutures. 
Abdomen convex, formed of a single piece, with a slight 
transverse impressed line, indicating the partial separation 
of an anterior segment; it is narrowed toward the posterior 
extremity : Which is terminated by a slight concavity. Head 
"marginate at the middle in front; cephalic suture distinct, 
p Parating a small segment from the posterior part of the 
' €yes strongly convex, laterally projecting ; a promi- 
aont minute tubercle just in front of each eye. External 
Menne half as long as the body; flagellum with ten 
