312 GEOLOGICAL SURVEY OF THE TERRITORIES. 
under side are much shorter and stouter than in ZH. texana; the stem 
is shorter and stouter than that of H. texana. 
Eighteen pairs of feet. 
Telson rather broad; along the dorsal edge are twelve pairs of acute 
spinules with the ustial lon g forked filament between the first and second 
pair of spines; the large terminal spines of the telson fringed with long 
hair-like set instead of spines, as in the Kuropean Limnadia gigas, but 
the tip is armed with minute short spines. A stout conspicuous spine on 
the lower angle of the telson under the terminal spines. A pair of long 
abdominal cirri. The eggs are yellowish and roughly granulated. 
Length of shell, 6.2™™; breadth, 3.8™™. 
About one hundred females, mostly with eggs, occurred in a small 
pool of fresh water on Penikese Island, Buzzard’s Bay, August 27, 1873, 
collected by Mr. Walter Faxon. Upon examining the pool the following 
July or August (1874), the young, about a line in length were found, 
but the pond subsequently dried up. ‘The eggs are yellowish and with 
‘the chorion roughly granulated. 
The species was dedicated to Prof. L. Agassiz. 
Compared with L. americana Morse, which closely secouttlies DT. gigas 
(received from Sweden through the kindness of Prof. W. Lilljeborg), it 
differs very decidedly in the “much narrower shell and fewer lines of 
growth. It belongs toa different genus from the two above-named spe- 
cies, agreeing in the structure of the animal and the bivalved carapace 
with L. antillarum Baird, Proc. Zool. Soc., 1852, 30, from St. Demingo 
(ig. 15), and L. texana Pack. From LZ. antiilarwm it differs in being 
more regularly oval and much more prominent behind the umbones. 
It also agrees with Baird’s description of ZL. antillarum in its two large 
terminal caudal spines being hairy, it having eighteen feet and nine- 
jointed flagella. It differs from L. texana in the stouter haft-organ, be- 
ing less triangular i in outline; in the broader telson, on the upper edge 
of “which the teeth are less numerous : in the smalier first antennee, and 
the less spiny second pair; the shell differs in being more broadly ovate 
than in 7. texana, which is oblong, less concave along the dorsal edge, 
and it differs from that of H. texana in having four instead of five lines 
of growth, as in L. texana. 
EULIMNADIA TEXANA Packard. 
Plates VI, VII, figs. 1-4. 
Hulimnadia terana Packard, Amer. Jour. Sc., vol. ii, Aug. 1871. 
Carapace valves rounded, oval, whitish, with 5 concentric lines of 
growth; shell very minutely punctured; these markings being coarser at 
the posterior end of the shell, where they are arranged in lines parallel 
to the edge of the shell ; eyesdouble, but with the inner edges contiguous. 
Twenty body-segments behind the head, including the telson; 18 pairs 
of feet ; first antenne extending to the first joint of the flagella of sec- 
ond pair; the latter each 9-jointed, each joint above with 4 or 5 stout 
sete, and beneath with long spinulose sete. First pair of legs of male 
with a slender hand; the claw moderately large, the fifth endite very 
long and slender. 
Telson with sixteen fine teeth above, not including the terminal acute 
spine; caudal appendages long and slender, knife-shaped, the under 
edge fringed with long hairs; the upper edge straight. the end blunt, 
with the lower ed ge slightly curved. The eggs are yellowish and pen 
tagonal in outline. 
Length of shell, 7™™; breadth, 4™™. 
08 Quite common in many places i in Western Texas in the early spring” 
