796 THE VOYAGE OF H.M.S. CHALLENGER. 



pectinate, the upper half fringed with small spines; the palm and finger as in the first 

 pair, but smaller, the palmar spine not having the tooth at right angles to its inner 

 margin. 



First Perseopods. — The side-plates narrow above, the oblique front margin forming 

 an acute angle with the long almost straight lower margin, the plate deeply excavate 

 behind, so as to receive in the hollow nearly the whole of the following side-plate. 

 The branchial vesicles like the preceding pair or rather longer, much longer than the 

 first joint of the limb. The first joint slender, reaching much beyond the side-plate, 

 with spinules or setules along the front margin, and a long feathered spine at the hinder 

 apex ; the second joint short, with a very small distal lobe in front, such as there is also 

 on the first joint ; the third joint shorter than the fourth, with three very slender genicu- 

 late spines standing out from the hind margin, the lowest much the longest ; the fourth 

 joint about as long as the fifth, narrowing distally, with slender spines at two or three 

 points of the front margin, and five or six of the hinder, the lowest here being of great 

 length ; the fifth joint with very slender spines at three points of the front margin, 

 and spines at ten points of the hind margin, the lowest much stronger than the rest 

 and apieally hooked ; the finger with a small dorsal cilium near the base, a short 

 nail, and a small decurrent tooth -spine at the base of it on the inner margin. 



Second Perseopods. — Side-plates small, excavate behind, the hind margin below 

 the excavation straight, the continuous curve of the front and lower margins scarcely 

 extending bej^ond the preceding side-plate. The branchial vesicles like the preceding 

 pair. The limb very little difi"erent from that of the preceding pair, with two or 

 three long slender spines on the margins of the first joint, perhaps only accidentally 

 missing in the first perseopods ; the fourth joint with spines of various sizes at eight 

 points of the hind margin, the front margin of this and the following joint pectinately 

 furred. 



Tliird Perseopods. — Side-plates very much broader than deep, bilobed. The 

 branchial vesicles as in the preceding pairs, but smaller. The first joint longer than 

 broad, the front margin descending lower than the hinder, which rises higher than the 

 front, the lower part of the front margin carrying five short stout spines, the central 

 part of the hind margin having five rather deep incisions, each with the usual cilium ; 

 the second joint is very short, with one spine at the front apex ; the third joint is much 

 shorter than the fourth, with nine long plumose setae on the hind margin, and at its 

 slightly decurrent apex a short spine and a long one with a very long accessory thread ; 

 it has short spines at six points in front ; the fourth joint is long, the margins serrate, 

 the front with spines at nine points, the hinder with eleven plumose setse interspersed 

 with long spines at five points, the spines stiff" at first, but where the accessory thread 

 arises becoming setae-like and very finel)^ pectinate ; the fifth joint a little shorter than 

 the fourth, spined at seven points in front and nine behind ; the finger slender, a little 



