﻿PTERYGOTUS BILOBUS. 



65 





, Head 



(1-7) 



=z 



2 



inches 



long bj 



3 



nches broac 



. 





Segment 



(8) 



= 



4 lines 





>) 



3 



33 



2 lines broad 





33 



(9) 



= 



8 



33 





>) 



3 



33 



3 



99 



g 1 



o \ 



33 



(10) 



= 



9 



33 





j> 



3 



33 



4 



33 



33 



(11) 



= 



9 



3 » 





> 



3 



33 



2 



33 



E-i 



31 



(12; 



= 



9 



S3 





» 



3 



33 



2 



33 





>3 



(13) 



= 



9 



33 





3 



3 



33 



2 



33 





V 



(14) 



= 



8 



33 





J 



2 



33 



6 



13 





f 



(15) 



= 



8 



33 





3 



2 



33 



2 



33 



cC 



93 



(16) 



= 



9 



33 







2 



S3 







33 



G 

 "c / 



33 



(17) 



= 



9 



3 3 





9 



1 



3) 



10 



33 



-3 



39 



(18) 



= 



10 



33 







1 



33 



6 



33 



<J 



33 



(19) 



= 



1 inch 







1 



33 



5 



39 





Telson 



(20) 



= 



1 



» 9H 



nes. 



9 



1 



>> 



5 



99 



TJie 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 cornea? of the eyes in PI. XIII, and of the detached head 

 figured on PI. XIV, 1 b, 1 c, 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 (PI. 

 XIV, fig. 1 c) and the cordiform metastoma, or post-oral plate, are both highly orna- 

 mented with squamate markings (PI. XV, fig. 3). 



The chelate antenna belonging to the specimen figured in PL XIII are 4^ inches 

 in length, and the chelae 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 antennae of var. a already 

 noticed. 



The endognaths agree in form with the previously described organs of var. a. 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 (PI. XIII, figs. 1 a, m, and 1 c ; PL XIV, fig. 2 -, 1 

 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 1| 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 PI. XIII, which was thus figured twice by 

 mistake. 



