REPOllT ON THE AMPHIPODA. 687 



edges of the first four pairs of side-plates and of the first joints of the last three pairs of 

 perseopods brought so closely into contiguity from either side of the body as to form a 

 straight ridge scarcely less sharp than the carina of the almost semicircular dorsal line. 

 From the very narrow front the body bulges greatly to the fourth or fifth peraeon- 

 segment, and then again narrows to end as sharply as it begins. Of the perseon-segments 

 the fourth, fifth, and sixth are the longest and deepest. The third segment of the pleon 

 has the postero-lateral angles sharp, in the slightest degree upturned. The fourth 

 segment has a deep dorsal depression, the part behind the dorsal depression strongly tip- 

 tilted, the sixth ridged on the back on either side of the telson. 



Eyes not discovered. 



Ul^per Antenna?. — In the male, first joint large and broad, the upper ridge continued 

 into a process overhanging the second joint ; the second and third joints short, very much 

 narrower than the first ; the flagellum of six joints, the first broad at the base, tapering, 

 as long as the other five united, with four rows of cylinders near the distal end ; cylinders 

 also on the next three joints ; the secondary flagellum very slender, of three joints, 

 together not equal in length to the first of the primary; of the three, the first longer than 

 the second, the third minute. In the female these antennae are slightly more slender, 

 the flagellum of five joints, with the first not quite so long as the other four united, the 

 secondary flagellum two-jointed. 



Lower Antennae. — Gland-cone prominent, third, fourth, and fifth joints subequal in 

 length in the male, the fifth slightly the longest, the flagellum in one of the pair of 

 antennae attaining the number of thirty-six joints, the first longer than the next two 

 together, the joints all gradually tapering, not bulging distally. In the female the third 

 joint is as long as the fourth, and each of these much longer than the fifth, while the 

 flagellum consists of four or five slender joints. In both sexes the fourth and fifth joints 

 of the peduncle are more or less ciliated above. 



Epistome. — The front of the animal is formed by the dorsal ridge of the first perason- 

 segment, the head and the upper antennae, so that it would be inaccurate to speak of the 

 epistome as prominent, but when the head and mouth-organs are detached and viewed 

 without the antennae, the expression would become appropriate. 



Mandibles. — The cuttins; edg-e convex, with a small downward directed tooth at the 

 top, and a very small forward directed tooth behind the rounded lower angle ; secondary 

 plate strap-shaped, bent, the apex cut seemingly into three denticles ; spine-row of three 

 slightly curved spines ; the molar tubercle well forward near the spine-row, its oval crown 

 set with rows of denticles, and a central row of four or five more prominent and isolated 

 than the rest ; the slender palp, set far back, has on the long second joint near the apex 

 a row of six or seven spines, increasing successively in length as they approach the apex ; 

 on the upper half of the third joint eleven spines, the first six separated by a slight 

 interval from the apical five. 



