CRUSTACEA. 51 
relations which may exist between the marine and fresh water representatives of this inter- 
esting genus. 
To facilitate their researches, I subjoin the references I have gathered touching the history of 
the two species described by different authors. 
AGLEA LAVIS, Leach. 
Syv. Galathea levis, Latr. Encycl. Méth. Crust. Pl. cceviii, fig. 2. 
Aiglea levis, Leacn, Dict. Sc. Nat. XVIII, 1820, 49. 
Desm. Consid, Gén. Crust. 1825, 186, Pl. xxxiii, fig. 2. 
Latr. in Cuv. Régn. Anim. IV, (2d edit.) 1829, 84. 
GrirF. Cuv. Anim. Kingd. XIII, 1833, 184, Pl. vii, fig. 2. 
Mi. Epw. Hist. Nat. Cr. II, 1837, 258; Atlas du Régn. Anim. de Cuvier, Pl. 
xlvii, fig. 3. 
Epw. et Luc. in D’Orb. Voy. Amér. Mérid. VI, I. Crust. 1843, 34. 
Nic. in Gay, Hist. de Chile, Zool. III, 1849, 199. 
Dana, U.S. Expl. Exped. Crust. XIII, I, 1852, 476, Pl. xxx, fig. 6. 
AGLEA DENTICULATA, Nic. 
Syy. Aglea denticulata, Nic. in Gay, Hist. de Chile, Zool. III, 1849, 200, Lam. ii, fig 1. 
ZGLEA INTERMEDIA, Girard. 
Sprc. cHAR. Carapax finely punctate; rostrum moderate, acute, depressed (incurved) upon its 
middle, with its" point slightly turned upwards. Edges of carapax subdenticulated; denticula- 
tions more conspicuous on the stomacal region than on the branchial region. Anterior legs 
larger in the male than in the female; in both sexes the arm has a prismatic shape, and is 
denticulated upon its upper and its lower and inner edges; the external lower edge being nearly 
smooth. Carpus provided with two rows of subconical tubercles (teeth) upon its upper and 
inner portion. Hand exhibiting internally a flattened processus, often denticulated. Inner 
edge of claws tuberculous or subtuberculous. Abdominal segments divided into three lobes, by 
an undulating line forming a subaneate triangle upon each segment. * 
Desc. The body is very much depressed, longer than broad; anteriorly about half the width 
of the posterior margin. The depth upon the middle region is about equal to the width of the 
anterior region immediately behind the orbits. The margin of the carapax is sharp and slightly 
indentated; the outline is slightly incurvated upon the suture which separates the thoracic from 
the cephalic region. The latter, convex upon its middle, is terminated anteriorly by a subtri- 
angular, acerated, and carinated rostrum, slightly raised upwards upon its tip. On each side 
of the rostrum a semi-elliptical notch, at the external angle of which a small spine exists, con- 
stitutes the orbit. The suture, between the cephalic and thoracic regions, is very convex pos- 
teriorly upon the middle region, then slightly concave laterally and anteriorly, then again 
oblique towards the edge of the carapax. 
The thoracic region is divided by two longitudinally shallow and smooth furrows into three 
regions—a medial or cardial, and two lateral or branchial regions. Again, it divides trans- 
versally into three regions also—an anterior, a medial, and a posterior; the last embracing a 
very narrow space upon the posterior extremity of the carapax, and extending but very slightly 
upon the branchial regions. The central portion of the cardial region is slightly convex, and 
limited by a sinuating depression or groove. The last segment of the thoracic region is move- 
