176 DR. J. G, DE MAN ON THE PODOPHTHALMOFS 



I was inclined at first to regard this species as a mere local variety 

 of de Haan's Sesarma bidens, but after a more careful examina- 

 tion I consider it to be a distinct species. Sesarma Saswelli, 

 however, is most closely allied to Sesarma hidens, de Haan. As 

 regards tbe form and structure of the cepbalothorax, both species 

 closely resemble one another, not only with respect to the 

 upper surface and the form of the front, but also with respect 

 to the form ot" tbe joints of the male abdomen. The ambulatory 

 legs also completely resemble those of Sesarma bidens, as regards 

 the comparative lepigth and breadth of the joints ; and tbeir 

 coloration is the same in both species. S. HaswelU only differs 

 from S. bidens by the number and by the form of the tubercles 

 of the upper margin of the mobile finger. 



The mobile finger is a little less arcuate at its base than that 

 of Sesarma bidens, being more straight, and it is covered in the 

 right hand, which in our larger specimen is a little larger than 

 the left, with a longitudinal row of 18-19 tubercles, whereas in 

 the left there are only 16 tubercles. In Sesarma bidens only 

 13 tubercles are constantly found on the upper margin of the 

 mobile finger. These tubercles have a different; appearance in 

 the two species, extremely difficult to describe. 



In Sesarma guttata from the shores of Zanzibar, the mobile 

 finger is covered above with 12-13 tubercles; in this species 

 these tubercles are ovoid, rather prominent, and their longer 

 axis is transverse, making a right angle with the longitudinal 

 axis of the finger. These symmetrical tubercles completely 

 resemble some species of Cliiton, for they present a smooth 

 ridge in the middle, which runs in the longer axis of the tubercle 

 and which is transversely sulcate. 



In Sesarma bidens the tubercles are similar to those of /S', gut- 

 tata, but they are lower and much less prominent. In Sesarma 

 Saswelli, however, the tubercles are less distinctly Chiton-like ; 

 they are more depressed above and are scalariform, each tubercle 

 being nearly vertically deflexed at its distal margin towards 

 the vent ; they are transverse, as in all species of this section 

 of tlie genus, the longer axis being perpendicular to the axis of 

 the finger. 



In all other characters the hands are similar to those 

 of S. bidens. The outer surface of the immobile finger is 

 somewhat flattened, or slightly concave, presenting a slight 

 longi^.udinal, ridge-like elevation below, parallel to the under 



