434 GEOLOGICAL SURVEY OF THE TERRITORIES. 



The eyes. — Tlie eyes are mounted upon a stalk, and thus Nehalia may 

 be said to be essentially stalk-eyed. In this respect it is similar to the 

 eye of the Branchipodidce on the one hand, or to the eye of the Becapoda 

 on the other. They are inserted just above and slightly in front of the 

 1st pair of antennte. The cornea is considerably less in extent than the 

 end of the eyestalk itself, and in this respect differs from the eye of 

 Decapods. 



The antennce. — The two pairs of antennge are large, well developed, 

 and of nearly equal size in the female, but in the male the second pair 

 extend backward beyond the bases of the caudal ai^pendages. In the 

 1st pair the stem (scape or protopodite) is seen to be composed of fine 

 joints, the 1st, 2d, and 4th the longest, the 3d and 5th short. From 

 the scape arises the flagellum or endopodite, which has 16 well-marked 

 joints, each joint provided externally with numerous set£e; and besides, 

 there arises from the 5th joint of the scape or stem a scale-like unjointed 

 appendage, which may be regarded as an exopodite; if so, then the 1st 

 instead of the 2d antenn£e in the Phyllocarida bear a scale-like exopo- 

 dite ; the 2d antennse in Becapoda bearing the exopodite. The outer 

 edge of this exopodite is thickly fringed with numerous long, delicate 

 setse. It thus appears that what corresponds to the setse or protopo- 

 dite of the 1st antennae of Decapods consists of 5 instead of 3 joints. 



The 1st antenna of Nehalia may be compared with that of the first 

 stage of the larval lobster (Smith, PI. XV, fig. 8) at the period when 

 the exopodite is short, scale-like, and single-jointed. 



The 2d antennae have a 2-jointed stem or scape (protopodite), and a 

 single long many-jointed flagellum orendopodite, the basal joint a large 

 one; no exopodite being present, even in a rudimentary form. 



The 1 st and 2d autennse are thus seen to be quite unlike those of the 

 Malacostraca, and _tQ resemble the Copepods, in that the anterior pair 

 ^are rather the stouter of the two; but in those Copepods with very long 

 antennae it should be remembered that they are the 1st and not the 2d 

 pair, as in the male Nebalia. It will thus be seen that while the anten- 

 nae of the Phyllocarida are entirely unlike those of the Phyllopoda, they 

 are neither closely homologous with those of the Becapoda (Mysis or 

 Cuma) or the Copepoda. 



The 2d antennae of the male is said by Claus to be very long, and to 

 resemble those of male Cumacece, but upon a comparison the stem of the 

 antenna is in Cuma quite different in the relative length of the three 

 joints. So also, while, as Claus observes, they are like the antennae of 

 the Awpliipoda^ this resemblance is qmt6 general; on the whole, how- 

 ever, the antennae of both pair bear a general resemblance to the Mala- 

 costracous type; also, on the other hand, they may also be compared 

 with the more primitive Copepodous type. 



The mandibles (PI. XXXVI, fig. 4; fig. 2, md). — These are remarkable 

 from the small size and weak development of the biting edge or mandi- 

 ble itself compared with the palpus. The oval or biting end of the 

 protopodite is small, and armed with comparatively few and weak setae, 

 which shows that the Phyllocarida probably feed on decaying animal 

 and vegetable food, which is easily brushed into the mouth by their 

 slight stiff bristles. The palpus, however, is enormously developed, 

 extending out quite to, if not a little beyond, the edge of the carapace 

 (Fig. 1). It is 3-jointed; the 2d a little longer than tbe basal, and 

 swollen at the base, while the 3d is somewhat longer but slenderer, and 

 edged with a fringe of close-set, rather stiff setae. Though so immensely 

 developed as to the palpus, and entirely unlike the mandible of the 

 PhyllojDoda, in which only the protopodite is developed, it may be com- 



