PTERYGOTUS BILOBUS. 65 
Head (1—7) = 2 inches long by 3 inches broad. 
Segment (8) = 4 lines yO) ben) 2 limes) broad: 
3 ” (9) = 8, ” 3. 35 3 ” 
3 re Oe saae Sa Me ae ates 
§ meat) == O'S, PRP OM oe asen Bee 55 
ES 4 Cray -==' Oe Sin Or ee 2 s 
tt qs) = 09... 3 Si N'33 2 55 
ee (IE) ities ee? $5 Dee 6 33) 
3 Glo = oB es, a5 De a 55 2 o 
= elo) 0" 3 A? 62 ae 0 5 
Ss 5 (072 jae — ae! Ds Hs ss 10 35 
5 pe weray S104 oan) gf” piltons 
= oy (19) =) Linteh ga Shea ‘a 
Telson, (20), = 1 jpidilines .,) daa eine 5 
The head is nearly one third broader than long, semicircular in front, the large com- 
pound eyes forming prominent projections on the latero-anterior border about 10 lines in 
length. The facetted corneee of the eyes in Pl. XIII, and of the detached head 
figured on Pl. XIV, 1 4, 1 ¢, can be distinctly seen with a good pocket-glass. 
The larval eye-spots, or ocelli, are also clearly seen in the centre of the carapace of 
all the specimens figured. 
The surface of the carapace is destitute of squamate markings or any other kind of 
ornamentation whatsoever; but the surfaces of the coxal joints of the ectognath (Pl. 
XIV, fig. 1c) and the cordiform metastoma, or post-oral plate, are both highly orna- 
mented with squamate markings (Pl. XV, fig. 3). 
The chelate antenne belonging to the specimen figured in Pl. XIII are 43 inches 
in length, and the chele are 5 lines broad. The length of the movable ramus of the 
chela is 1 inch; the inner border of both rami are closely planted with large and small 
sharply pointed teeth. They closely resemble in form the antennz of var. a already 
noticed. 
The endognaths agree in form with the previously described organs of var. 2, The 
woodcut figure of a detached endognath given at page 59 (fig. 11) probably belongs 
to this variety, with which its size well agrees. 
The metastoma or post-oral plate (Pl. XIII, figs. 1 a, m, and 1; Pl. XIV, fig. 2 ;? 
and Pl. XV, fig. 3) is oblong oval, deeply bilobed in front, and slightly truncated along 
its posterior border. It is closely covered, especially upon its anterior and bilobed portion, 
with minute squamate markings. The detached lip-plate (fig. 3, Pl. XV) is 2 inches 
4 lines long and 14 inch in breadth near the centre, representing an individual not less 
than 18 inches long. 
Although the thoracic plate or operculum is discernible in the specimen figured in 
1 This lip-plate belongs to the specimen figured in Pl, XIII, which was thus figured twice by 
mistake. 
