300 GEOLOGICAL SURVEY OF THE TEERITOEIES. 



tliey appear to be very hardy compared with the Branchipodidte. The 

 auiinals are pale flesh-colored, with black eyes, and are tolerably rapid iu 

 their movements, swimming often on their backs and rapidly gathering 

 the vegetation at the surface with their antennae and either their coxal 

 lobes or jaws. The eggs are carried upon the back under the shell, and 

 are found in the spring. 



We have received numbers of the cast shells of the larva or naui)lius 

 from a correspondent at Hanover, IST. H. The carapace bears a close 

 resemblance to that of the nauplius of the European L. hrachyura, hav- 

 ing the lateral front spines and two small caudal spines. 



LiMNETis MUCRONATUS Packard. 



Plate I, figs. 1-6. (In fig. 1 the Ist antennae are not represented by tlie artist.) 



lAmnetis mucronatus Pack., American Naturalist, ix, 312, 1875. 



Bulletin Hayden's U. S. Geological and Geog. Sarvey, iii, No. 1, 172, 1877. 



Male. — Carapace much flattened, oval-triangular, the dorsal edge of 

 the valve but slightly curved, the posterior end well rounded, while 

 the front end is but slightly curved. Head in front truncate, much as 

 in tlie males of L. gouldii and gracilicomis, the end being broad and 

 square. Hand large, a little longer than broad, wdth the claw large, 

 and as long as the hand is broad; the lower edge of the hand (or 4th 

 endite) armed much as in L. gouldii. There are twelve jiairs of limbs, 

 the twelfth ending in a pair of large, strong, recurved hooks. The 

 end of the terminal segment on its ventral side is rather more pro- 

 duced, and with a more conspicuous spine than in the female. Two 

 males occurred among forty -four females. 



The length of carapace, 4>""; breadth, 3.2"^™. 



Female. — Carapace scarcely distinguishable from that of iy.^rac^7^cor%^s 

 in outline, though it varies slightly in form, some being quite round 

 and regular, others slightly ovate, and some quite flat and triangular. 

 Muscular impression as in L. gracilicomis, but the muscular impression 

 is much broader and j)roportionately shorter than in L. gracilicornis, 

 where the front of the head is suddenly truncate, and w-ider at the 

 extremity than behind in gouldii; while iu gracilicornis it is also trun- 

 cate, but does not contract so much in 

 front of the eyes, the narrowest point be 

 ing between the eyes and the end of the 

 front. In the present species, however, 

 the front is very much produced into a 

 long, acute, mucronate point, with two 

 teeth on each side, the middle tooth vary- 

 ing much iu length. The carina is very 

 high and sharp (see a in Fig. 3 in text). 



Fig. 2. — T.ymnetis mucrovatiis, male; a,.-.-, , •\.i\li j • • x t_ ij? 



claw; both enlarged, isc anteonas aot 2d autenuse With the sccoud joiut half as 

 drawn. Emeiton del. long as the basal; the four succeeding 



joints very close, and together not as long as the succeeding seventh 

 joint, from which arises the flagellum, the upjDcr branch of which is 

 14-15-jointed, the lower one 17-jointed, with ciliated hairs about as long 

 as in L. mucronatus, the longest ones as long as the entire antenna. 

 Twelve pairs of feet. 



The feet have a very long and slender flabellum, the gill being either 

 in the first pair short and rounded at the end, or in the second and suc- 

 ceeding ones long and pyriform, being about the same shape and size 



