264 



S. I. Smith — Tropical and Sub-tropical 



another specimen found at Woods' Holl. These two specimens are 

 very nearly of the same size, the last one being very slightly the 

 larger. 



These young specimens, though having most of the essential spe- 

 cific characters of the adult Calappa marmorata, yet differ so much 

 that they might readily be mistaken for a distinct species Avhen com- 

 pared with large specimens. The carapax is much narrower than in 

 the adult, the breadth, including the lateral teeth, being only about 

 a fourth greater than the length. The dorsal surface is more convex 

 and more tuberculose, the tubercles being proportionally much larger 

 and more prominent, giving the carapax a much rougher appearance. 

 In fact the carapax resembles that of C. convexa of the west coast 

 of America more than it does the adult marmorata, except that it 

 has not the crenulated transverse carinae above the posterior margin 

 and the similar carinae upon the teeth of the postero-lateral margin. 



The C, convexa is sufficiently distinguished from the marmorata 

 by these crenulated carinae, though the proportions of the carapax, 

 which are given by Stimpson as distinctive, are wholly inadequate to 

 distinguish it, as the following table of measurements will show. 

 Stimpson evidently compared small specimens of convexa with large 

 ones of marmorata without making sufficient allowance for the 

 changes in the proportions of the carapax with increasing size. 



In the last division of the following table, the breadth of the 

 carapax is given just in front of the three most posterior teeth of 

 the lateral margin, and the breadth given in each of the last two 

 divisions of the table is given first in millimeters and then in the 

 length of the carapax as a unit. 



Locality. 



C marmorata 

 Vineyard Sd.,... 



Bermuda, 



Key West, 



Egmont Key, — 



u 



Key West, 



Brazil, - 



C. convexa. 

 La Paz, L. C.,... 



Length of 

 Carapax. 



2 2-0" 



22-5 



34-3 



47-1 



540 



58-0 



69-0 



73-5 



Breadth of carapax : 



Including teeth. 



27-0° 

 28-4 

 46-5 

 66-0 

 78-0 

 84-9 

 10G3 

 111-0 



1-23 Igth. 



1-26 



1-35 



1-40 



1-44 



1-46 



1-54 



1-59 



In front of teeth. 



-15 

 •16 

 -22 

 -31 

 -30 

 -33 

 -30 



70-0 1-30 



101-2 1-31 



119-0 1-38 



1400 1-40 



Igth. 



