ORTMANN: CRUSTACEA OF SOUTHERN PATAGONIA. 657 



to resemble those of H. patagonica, although the description is very short 

 and incomplete. 



This species seems to be the most closely allied form among those 

 described by Wrzesniowsky ; it differs, however, distinctly in the shape 

 of the eyes and the length of antennulae and antennae. 



H. warm ingi Stebb. , from Lagoa Santa, Brazil. 



This species differs at once and strikingly in the shape of the propodite 

 of the second gnathopod of the d\ which is more oval, and in the shape 

 of the first gnathopod and the second gnathopod of the 9. Also the 

 antennas are much longer, so that we do not need to compare it further. 



H. meinerti Stebb., from " Laguna di Espino." 



This is entirely different in the third uropods, which resemble those of 

 H. longistilus (Fax.), and further, the shape of the first and second 

 gnathopods and the length of the antennas are quite unlike our species. 



Thus we see that the species most closely allied to H. patagonica is H. 

 inermis of the United States. According to Faxon, this species (or variety) 

 is also found in Peru, near Lake Titicaca, and in the region of the Straits 

 o Magellan. Yet Faxon regards differences in the shape of the first and 

 s -cond gnathopods not as specific characters, and thus it is quite possible 

 *nat his South American specimens represent good species, different from 

 H. inermis. I have said above that the differences of H. patagonica from 

 H. inermis, although seemingly unimportant, are constant among the 

 large number of oui^Sp^i'^ens, and consequently, I am forced to regard 

 this Patagonian form as fr^Mfc and good species. 



The fact that the type of fresh-water amphipods, represented in the 

 United States by Hyalella dentata and inermis extends, apparently, 

 throughout America, over Central and South America to the Straits of 

 Magellan, while this genus is found nowhere else, is very interesting from 

 a zoogeographical point of view. 



Order DEC APOD A. 



Family LITHODID^E Dana. 



LITHODES Latreille. 

 LITHODES ANTARCTICA (Jacquinot). 



1891 L. a., A. Milne-Edwards in : Miss. Cap Horn, v. 6, p. 24. 

 1896 L. a., Bouvier in : Ann. Sci. nat, ser. 8, v. i, p. 23. 

 Locality. Punta Arenas, 2 cT i 9 



