ORTMANN: CRUSTACEA OF SOUTHERN PATAGONIA. 641 



front, diverging behind. First cervical furrow almost straight, second one 

 strongly curved backward in the middle, and slightly shallower in the 

 middle, but distinct. Median keel indistinct anteriorly, very distinct pos- 

 teriorly. Lateral margins smooth, only near the posterior corners, for a 

 short distance, very finely crenulated. Posterior emargination with small, 

 somewhat irregular spinules, the median one (end of median keel) the 

 largest. Supra-antennal keel slightly sinuate, apparently smooth, but 

 under the lens there are fine and minute granulations. 



Flagella of first pair of feet short, unequal, slightly depressing the margins 

 of the scutum. Free abdominal segments spinulose, about 6-8 spinules 

 on upper side ; these are larger, straight, and arranged somewhat irregu- 

 larly ; those of the ventral side are smaller, numerous. 



Telson (fig. ib] on upper side, near base of cercopoda, on either side 

 with a small, spinulose tubercle. Caudal flap elongate, over twice as long 

 as wide at the base, with parallel margins, sublanceolate at the end and 

 rounded ; distal half of margin spinulose, with the strongest spinule at 

 the end. Upper surface with a median, longitudinal keel bearing four 

 strong spinules. 



Cercopoda almost as long as the rest of the body, thickly covered with 

 bristles. 



Color deep green, lower parts pale greenish, mandibles brownish. 



Size : Length of body 40 and 46 mm. Total length of larger indi- 

 vidual (including cercopoda), 77 mm. 



Remarks. At first there seemed to be no doubt to me that our speci- 

 mens ought to be referred to L. patagonicus Berg (1900), which comes 

 from near the same region (Territ. of Chubut), but a careful comparison 

 of our specimens with Berg's description reveals the following dis- 

 crepancies : 



1. Of the abdomen, only 10 segments are exposed in our species, while 

 in L. patagonicus 15-16 are seen. Thus the abdomen of the latter appears 

 to be longer. 



2. In L. patagonicus the eyes are said to be suboval, and not to approach 

 one another anteriorly, while in our species they are elliptic and distinctly 

 convergent in front. 



3. The lamina caudalis, in L. patagonicus, is one third longer than 

 broad ; in our species it is distinctly more than twice as long as broad. 

 This is the most striking difference. Through the kindness of Mr. A. J. 



