388 MRS. E. W. SEXTON ON A [Apr. 28, 



about 10 groujDS in each row; the remaining six joints taken 

 together are twice the length of thefli-st. T\\e accessory flag elhmi 

 is ti'i-articulate. 



In the young form (PL XVIII. fig. 5) the 2nd and 3rd joints 

 of the peduncle taken together are equal in length to the 1st. 

 The primary flagellum is very little longer than the peduncle, 

 and is composed of four joints, the 1st the longest ; the 2nd and 

 3rd are each armed with a stiff spine, similar to those of the 

 adult ; the apical joint is tipped with a long bristle, four simple 

 seta?, and one auditoiy. The accessory flagellum is biai-t.iculate, 

 and much longer than in the adult, equalling the first and 

 second joints of the primary flagellum taken together. There is 

 an auditory seta on each joint. 



Inferior Antenna. — Adult (PI. XYIII. fig. 6). About twice 

 the length of superior antenna. The 1st joint of \}aQ peduncle is 

 produced posteriorly in a thick lobe, a little hollowed behind ; 

 the 2nd joint is small, the antennal cone large in proportion ; 

 the 3rd is as wide as long, broadening distally ; the 4th exceeds 

 the 5th in length and is much broader. The first three carry no 

 seta? ; the 4th has twelve long auditoiy setae along the posterior 

 mai'gin, nine of which are inset on the inner surface and three on 

 the outer ; the anterior margin carries seven groups of long fine 

 sette pi'oximally, and seven clustei's of small setae arranged in 

 transvei'se rows across the margin ; six of these little groups are 

 continued down the 5th joint. At its distal posterior angle there 

 is one long auditoiy and one simple seta. 



Hh.e flagellum, which is about a third longer than the peduncle, 

 has 25 joints, the first the largest, decreasing gradvially to the 

 tip which carries one long stiff' bristle, two fine setae, and one 

 small one ; each joint has a row of small setae anteriorly, inset a 

 little above the distal angle. 



In the im7nature form the proportions of the peduncle joints 

 are the same. The 4th joint carries six of the auditory setae ; 

 the 5th has four setae at intervals on the anterior margin and 

 one auditory one distally, and one auditory and one fine seta 

 posteriorly as in adult. The flagellum has only 10 joints, the 

 first the largest ; all the joints are provided with the little rows 

 of setae as in adult. 



In the young (PL XYIII, fig. 7) the flagellum is shorter than 

 peduncle and consists of only four joints, the first of which much 

 exceeds the other three taken together in length, each furnished 

 distally with a cluster of leather long set*, the ajoical joint 

 carrying one long stiff bristle and four small setae. 



Oral Parts (PL XYIII. fig. 8). — Upper cond Lotcer Lips 

 (figs. 9, 10, & 11). The upper lip is elongate, apex emarginate ; 

 the lower lip is of a more delicate structure, bifid, with the lobes 

 lanceolate ; both lips so hollowed as to appear very nai'row, but 

 when flattened out, of considerable breadth. 



Mandibles (PL XYIII. fig. 12). — Strong basal portion carry- 

 ing the large palp, produced forward as a long narrow process ; 



