AMPLINUS. lol 
Hab. Costa Rica! (Biolley). 
This species is known to me only from Carl’s figure and description. From the 
other species with polygonal sculpturing it differs in having the median area of 
segments | to 6 smooth and the posterior angle of the keels rectangular. It is also 
characterized by its large size, a feature in which it most resembles A. areatus, but has 
the terminal branches of the phallopod much more widely separated and the auxiliary 
branch more strongly arcuate. 
4. Amplinus areatus, sp.n. (Tab. XI. figg. 4-4 f) 
Colour dark brown with posterior row of polygonal areas paler; external half of keels yellow; antenne 
brown, much darker than yellow area of keels; legs with two basal segments yellow, the rest brown 
like the antenne. Closely allied to A. flavicornis, but larger and with the legs and antenne much 
darker tinted ; the keels a little better developed, with the posterior angle a little more produced ; the 
median area of the Ist tergal plate sculptured, though the sculpturing is weaker than at the sides and 
the antero-lateral notch on the keels of the 2nd and 3rd marked in front by a distinct but small tooth. 
Phallopods rather like those of A. flavicornis, but the terminal portion which carries the two branches 
narrower, with its flattened internal face less well-defined above and below and with its lower rim not 
produced into a definite crest; the terminal branches shorter and less curved distally. 
Length, 9, 70 millim., width 11. 
fab. N.W. Guatemata, La Tortuga, Retalhuleu (Séol/). 
5. Amplinus flavicornis, sp. n. (Tab. XI. figg. 2-2 f.) 
Colour brown with the margins of the keels yellow; antenne and legs rather paler yellow than the keels. 
dé. 
Summit of head smooth. Sculpturing of dorsal area consisting of three rows of smooth polygonal areas 
which at most show laterally a tubercle now and again on some of the segments. First tergal plate 
with sculpturing obsolete in the middle, laterally with four rows of areas which decrease in number 
and increase in distinctness on the keel, which is well developed, with very obtuse anterior angle and 
subacute but blunt posterior angle. The 2nd, 3rd, and 4th with convex anterior and lightly concave 
posterior border; the anterior angle obtuse, marked by a notch; the posterior subacute. In the 
succeeding segments the anterior margin of the keel is lightly convex and runs into the somewhat widely- 
rounded anterior angle, not serrulate; posterior border straight or lightly concave, finely serrulate from 
about the 5th; the posterior angles slightly produced but never sharp or spiniform, those of the 17th, 
18th, and 19th more produced than the others; lateral border of the poreless keels nearly straight and 
moderately thickened ; other pore-bearing keels considerably thickened and more sinuous in outline. 
Upper surface of the 19th with two rows of subtuberculiform areas. Caudal process smooth, mesially 
depressed, its posterior border lobulate. -Anal sternal plate emarginate between the thickened tubercles. 
Lateral surface of segments granular. Underside of outer half of keels smooth. 
Similar to the 2, but with the keels better developed. Phallopods rather slender, ending in two slender 
pointed terminal branches which are rather narrowly separated, both being curved distally towards the 
middle line ; the superior border of the slightly hollowed area at the base of the fingers with a distinct 
upstanding crest ; the hollowed area wide and well-defined. 
Length, 2, 58 millim., width &. 
” 3 9 53 99 a” 7. 
Hab. Centra America (Mus. Brit.). 
Related to A. nitidus, Brol., but differing from it in having the legs and antenne 
pale, instead of black or dark brown, and in the structure of the phallopod, in which 
