AMPLINUS. 149 
Solomon Islands [Ann. & Mag. Nat. Hist. (6) xx. p. 445, 1897], which is probably 
identical generically with P. granosus, the type of Polylepis, from the Moluccas. 
Afterwards came Attems, who, in spite of its preoccupation, resuscitated Pachyurus 
and divided it into two subgenera, Amplinus for the American species and Angustinus 
for the Oriental species. Giving these names generic rank, we get the following 
result :— 
Polylepis (= Paradesmorhachis= Angustinus) for the Oriental species with narrow 
first tergal plate. Type, P. granusus, Humb. & Saussure. 
Amplinus, Attems, for the Central and South American species with broad first 
tergal plate. Type (by selection), A. kalonotus, Attems. 
Key to the Central-American Species *. 
a. Sculpturing of segments tessellated, consisting of three rows of low, smooth, 
polygonal areas. 
6. A median yellow band extending from the first to the last segment; keels 
wholly yellow. © 2. 2 2. we eee ee ee ee ww. pttlicaudatus. 
b'. No median yellow dorsal band ; keels at most with external half yellow. 
c. Median area of terga of segments 1 to 6 smooth and inconspicuously 
sculptured 2. 1 ke ee ee convetus. 
. Median area of terga of at least segments 2 to 6 conspicuously sculptured, 
7 Antenne and legs yellow, as yellow as the margins of the keels . . . flavicornis. 
d‘. Antenne and legs brown, much darker than the margins of the keels. 
e. Posterior angle of all the keels less produced, those of second to fourth 
segments nearly rectangular ; the anterior tooth on these segments 
small ; phallopod with auxiliary branch bigeniculate . . . . nitidus. 
. Posterior angle of all keels more produced, those of second to fourth 
segments acute; the anterior tooth on these segments stronger ; 
phallopod with auxiliary branch simply curved . . . . . . . areatus. 
a’. Sculpturivg consisting of round, oval, or fusiform smooth tubercles, which on 
the posterior segments, at least, consist of about five irregular transverse rows. 
f. Lateral edges of the keels distinctly toothed . . . . . «© «© « «© | armatus. 
f’. Lateral edges of the keels not distinctly toothed. 
g. Phallopod 3-pronged; keels smaller, more depressed, with edges not so 
strongly thickened . . . . : triramus. 
g'. Phallopod 2-pronged ; keels larger, more horizontal, with edges strongly 
thickened . 2. 2. ww eee eee ee we Klug. 
1. Amplinus nitidus. (Tab. XI. fig. 3.) 
Platyrrhachus nitidus, Brdlemann, Mém. Soc. Zool. France, xii. p. 97, t. 6. figg. 18-20 (1900) '. 
Pachyurus nitidus, Carl, Rev. Suisse Zool. x. p. 638 (1902) ?. 
A jet-black, shining species, with black antenn and dark brown legs, and with the external half of the keels 
clear yellow and sharply contrasted with the black of the rest of the dorsal surface. The sculpturing 
* A. erichsoni, of which the distinctive features are unknown, has been omitted from this Table. 
