28 S. J. Smith on lirazllian, Crustacea. 



This genus has much tlie aspect of Peneus, and is closely allied to 

 it in the antennas, maxillipeds, anterior tlioracic legs and abdomen, 

 but differs from it remarkably in the carapax, antennute and posterior 

 thoracic legs. 



Xiphopeneus Harttii, sp. nov. 



Plate I, figure 1. 



The carapax is not at all swollen ; a very slight, rounded dorsal 

 carina extends from tlie base of the rostrum to the posterior border ; 

 the cervical and branchio-cardiac sulci are very distinct, and together 

 form a nearly straight groove from near the base of the antennas al- 

 most to the posterior border; the inferior margin of the carapax is 

 nearly straight, jjrojecting slightly along the branchial region ; the 

 antennal spine is prominent and rather stout, and the hepatic spine 

 slender and acute. The rostrum is very long and slender, in length 

 nearly equalling or considerably exceeding the carapax, wholly un- 

 armed below, but the basal portion armed above with a thin and liigli 

 carina, w^hich extends back upon the carapax a short distance, and for- 

 ward as far as the eyes, and is armed with five sharp and prominent 

 teeth, and at its posterior extremity with another tooth which is 

 smaller, much below the level of the others, and separated from them 

 by a considerable space ; tlie j^ortion in front of the eyes is nearly 

 straight or a little upturned, sub-cylindrical, slightly flattened laterally, 

 unarmed, perfectly smooth and tapers to a very slender point far in 

 front of the antennal scales. 



The eyes are of moderate size, and the peduncles much shorter than 

 in most species of Peneus. 



The appendages upon the inside of the peduncle of the antennulae 

 are siirmounted by a tuft of hairs which fills a little depression in the 

 ocular peduncle. The first antennulary segment in advance of the eye 

 is sub-cylindrical, flattened on the under side, and nearly as long as 

 the peduncle of the eye ; the next anterior segment is cylindrical and 

 one-half as long as the last. The upper flagellum of the antennula is 

 slender, about three times as long as the carapax, and has a short 

 portion at the base slightly thicker than the rest ; the lower flagellum 

 is very slender and about half as long as the upper. 



The basis of the antenna is armed with a small, sharp spine just be- 

 low the articulation of the antennal scale. The antennal scale reaches 

 to the base of the flagella of the antennula, is much narrowed toward 

 the tip, the outer margin is straight and armed with a sharp tooth at 

 the anterior extremity, and the inner margin is nearly straight and 



