1 882.] Representing tlie order Phyllocarida. 863 



senting the carapace removed from the body and flattened out, 

 there are no signs of a median hinge-joint. 



The nature of the rostrum is one of the diagnostic features of 

 this order. In Nebalia the rostrum is long and narrow, oval, seen 

 from above, terminating in an obtuse point quite far in advance 

 of the head. It is loosely attached to the sinus in the front of 

 the carapace, and thus forms a long, narrow, tongue-like flap, 

 with a free movement up and down. It is thus seen to be rather 

 a movable appendage of the carapace than a solid, immovable 

 continuation of it, as in the Decapoda. Upon removing the cara- 

 pace and flattening it out, it is seen to be readily comparable with 

 the carapace of Ceratiocaris. 



The eyes. — The eyes are mounted upon a stalk, and thus Ne- 

 balia may be said to be essentially stalk-eyed. In this respect it 

 is similar to the eye of the Branchipodidae on the one hand, or to 

 the eye of the Decapoda on the other. 



The antenna. — The two pairs of antennae are large, well devel- 

 oped, and of nearly equal size in the female, but in the male the 

 second pair extend backward beyond the bases of the caudal 

 appendages. In the 1st pair the stem (scape or protopodite) is 

 seen to be composed of five joints, the 1st, 2d and 4th the longest, 

 the 3d and 5th short. From the scape arises the flagellum or en- 

 dopodite, which has sixteen well-marked joints, each joint pro- 

 vided externally with numerous setae ; 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 antennae in the Phyllocarida bear a 

 scale-like exopodite; the 2d antennae in Decapoda bearing the 

 exopodite. 



The 2d antennae have a two-jointed stem or scape (protopo- 

 d 'te), and a single, long, many-jointed flagellum or endopodite, 

 the basal joint a large one; no exopodite being present even in a 

 rudimentary form. 



The 1st and 2d antennae are thus seen to be quite unlike those 

 of the Malacostraca, and to resemble those of 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 remem- 

 bered that they are the 1st and not the 2d pair, as in the male 

 N ebalia. It will thus be seen that while the antennae of the Phyl- 

 locarida are entirely unlike those of the Phyllopoda, they are 



