346 GEOLOGICAL SURVEY OF THE TERRITORIES. 
2-jointed, 2d joint about two-thirds longer than the 1st, tapering towards 
the end; basal joint curved a little at the base. 2d antenne or clasp- 
ers large and tortuous; the basal joint extends outward and downward ; 
the 2d joint extends backward parallel to the body, and is bent at ri ioht 
angles to itself, and the 2: is directed forwards and inwards, the ends 
nearly meeting over the median line of the body; 3d joint short, swol- 
len, and subdividing into three branches, the longest of which reaches 
in its natural position to the 8th segment behind the Ist antennary seg- 
ment. An antenniform appendage springs from the end of the basal 
joint and reaches to the end of the 5th ring behind the eyes; it is slen- 
der, flattened, and much as described in S. similis Baird. At the end 
on the outside of the 2:1 joint is an acute, short, flat, conical appendage. 
Of the two terminal large appendages, the longer and slenderer one is 
sinuate and sends off a slender spur from the base, reaching nearly to 
the bend in the appendage, where there is a slight projection, beyond 
which it is long and slender, flattened, cylindrical. The other append- 
age is irregularly flattened, very sinuate, and about two-thirds as long 
as the other. Near the base on the outer edge are two flat lamellate 
teeth, the inner much the smaller and slenderer; the outer broad and 
suddenly ending in a finger-like point, the appendage ending abruptly 
in an acute point. For want of material it is difficult to draw up a good 
comparative description of the appendages of this species as compared 
with A. floridanus and A. sealii. 
By reference to the figures on Plate XII a good idea of the form of 
the appendages and their endites and exites can be obtained; but which 
characters are generic and which specific would be difficult to say. The 
1st endite is broad and large. with long, fine, hair-like sete; in the 8th 
pair the base of the edge of the 5th endite has six stout, truncated, short 
* spines (see Pl. XII, fig. 51°). The gills are oval, lanceolate in form; 
the flabellum rather broad and well rounded on the outer edge, which 
is serrate, the teeth giving rise to small, fine sete. 
The male reproductive. organs arise ‘from the Sth segment counting 
forward from the telson, or the 15th from the head, and are slender, 
simple, unarmed, cy lindtical, of the same thickness ‘throughout, with 
the end blunt, and are curved around so as to touch at their origin. 
Telson very short; caudal appendages but slightly separated at base, 
Jong and rather stout, gradually tapering to the end and well fringed 
on both edges. 
Length of the whole animal, 16.2"; length of longer appendage of 
2d antenne, 4.2"; length of caudal ‘sty lets, 3.2"; length of penis, 
bo ae 
Female. —Differs from the malein the 2d antennex, which scarcely reach 
beyond the 1st antennze, and which are flat, conical, ending in a finger- 
shaped point. Ovisae attached to the 13th and 14th segments behind 
the head; it reaches backwards to the segment in front of the telson, 
forming a long cylindrical sac ending in two valves, the upper one tri- 
angular, hollowed beneath, the under one short, forming the end of the 
ovisac. The external opening of the oviducts are situated on the basal 
segment of the abdomen. The eggs are a little the larger at the end of 
the ovisae. The caudal appendages are rather shorter and considerably 
stouter than in the male. 
Total length, 14"; of caudal appendages, 3"; of ovisac, 5™. 
This description is mainly based on the few examples received from 
Waco, Tex., through Mr. G. W. Belfrage, who found it in 1871, and again 
February li, 1872, with Limnetis and Estheria. Afterwards a lar ge num- 
ber, mostly immature, were eure from Dr. Watson, at Ellis, Kans., and 
