208 Mr. Lubbock on two new Subgenera of Calaaidae. 



Labidocera (Ivella) Patagoniensis. 



There being only one species as yet in the subgenus, no spe- 

 cific description need be given. 



Colour ? 



Length, from the rostrum to the end of the abdomen, in both 

 male and female, J- inch. 



Taken by Mr. Darwin with Labidocera Darwinii in the open 

 sea, lat. 38° south, off the coast of Patagonia. 



This species appears rare ; at least there were only a few spe- 

 cimens, amongst a great number of L. Darwinii and other small 

 Crustaceans, caught in the towing-net. 



Labidocera [Iva) magna. 



Rostrum short (PL X. fig. 8). 

 flp^ pair of antennce. Male. 



The left is about -^-^ inch in length, simple, 24-jointed, and 

 clothed with hair, which is all on the external side, except some 

 fine down on the basal joints, and one simple hair at the apex of 

 the penultimate and antepenultimate segments. On the apex of 

 the eleventh segment is a strong spine. 



The right antenna (fig. 9) is very difiierent ; it consists of a 

 basal portion composed of many almost coalesced segments; 

 then a part very much swollen, and bearing a very large pre- 

 hensile spine, which is transversely ringed; the two segments 

 which succeed this swollen part are longer, and each bears a plate, 

 one with about twenty, the other about sixty teeth ; the following 

 segment (which probably consists normally of three) has two 

 plates, each with about forty teeth. These two plates rise one 

 on each side of the flat external surface of the segment, the one 

 occupying two-thirds at the middle, the other two-thirds at the 

 apex of the segment. There are in the three last plates two un- 

 equal rows, each provided with the above-mentioned number of 

 teeth, and the smaller row situated at the base of the larger. 



Second pair of antennce. Have been described above. 



Eyes. What has been said of the eyes of L. Patagoniensis 

 applies equally well to those of the present species. 



Mandibles gV of an inch in length ; bearing, like L. Pata- 

 goniensis, seven teeth, and a spine serrated externally. The first 

 six teeth are strong, large and subequal, decreasing in size from 

 the outside; the first is ^i^ inch in length, the seventh is 

 smaller. There are rows of hairs as in the preceding species. 



First pair of maxillipeds Jj inch. 



Second pair of maxillipeds. Length ^-^ inch ; of the palpus ^'jf. 



Third pair of maxillipeds. Length ^L inch. The bail's of this 

 organ have been described above. 



