596 CRUSTACEA. 



Anterior feet nearly naked, hand hirsute below. Six posterior 

 pairs nearly naked, penult joint somewhat armed below, tarsi un- 

 guiculate. 



Plate 39, fig. 4 a, animal (female), natural size, with antennae in 

 part mutilated, and part of the carapax removed, so as to show the 

 eye and base of inner antennae ; b, under view, showing mandibles in 

 natural position and base of outer antennae, magnified two and a half 

 diameters; c, second pair of maxillipeds, enlarged five diameters 

 (palpus, £>, and branchiae, h, mutilated); d, outer or third pair, ibid.; 

 e, base of first pair of legs ; /, extremity of moveable finger of second 

 pair of legs ; g, part of third flagellum of inner antennae, enlarged ; h, 

 profile of beak, natural size. 



Fresh-water streams, Chili, fifty to one hundred miles from the sea. 



Length of body, three and three-fourths inches. Colour, olive- 

 green. Carapax smooth and naked ; a spine on front margin, half 

 way between beak and outer angle. Fingers of hand of second pair 

 subcylindrical. Hand of first pair nearly half shorter than carpus. 

 Penult abdominal segment half longer than the preceding, and below 

 triangulate and acute behind at middle, the extremity of the triangle 

 being prolonged into a slender and hardly acute spine. Abdominal 

 appendages calcareous, outer lobe of base nearly rounded or subacute, 

 and minute hirsute at margin, outer scale with the transverse suture 

 triangulate, and having a small D-shape areolet in the bottom of the 

 triangle, which the suture includes. 



Subfamily OPLOPHORINJE. 



The species of this family observed by us constitute the new genus 

 Regulus, and are brilliantly phosphorescent. They have the second 

 pair of feet stoutly chelate, as in Palaemon, also a serrated beak ; and 

 the mandibles bipartite above and palpigerous. They, therefore, 

 appeared to be of that family. But, as in Oplophorus, the basal scale 

 of the outer antennae is long and narrows to a sharp point, a character 

 not found among other Macroura, and the outer margin of this scale 

 is dentate or spini-dentate ; moreover, a segment of the abdomen is 



