128 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.47. 



follows: The upper margin of the orbit is much less obHque. The 

 hiteral angle of the carapace, marking its greatest width, is farther 

 back. The gi*anules of the palm are of more uniform size. The 

 palm is scarcely depressed near the immovable finger. The dac- 

 tylus is more strongly arched. The transverse ridge across the inner 

 surface of the palm is very prominent, is bent at an obtuse and 

 rounded angle and is armed for nearly its whole length Avith a row 

 of large tubercles. Near the proximal lower corner of the inner sur- 

 face there is a longitudinally oblique stridulating ridge extending 

 from the articulation mth the carpus to the lower marginal line of 

 the palm almost below the angle of the transverse ridge. The strid- 

 ulating ridge is made up of closely placed parallel lines obUque to 

 the axis of the ridge and subparallel to the lower margin of the 

 palm. Wlien the cheliped is flexed the ridge plays against a line of 

 granules on the lower or anterior surface of the first ambulatory leg; 

 this line extends nearly the whole length of the carpal segment and 

 part way along the merus. The third to sixth abdominal segments 

 of the male are more completely fused. 



EXPLANATION OF PLATES. 



Plate 1. 



Trizocarcinus dentatus, male type, X 2.. 



Fig. 1. Antero- ventral 'View. 



2. Dorsal view. 



3. Posterior view. 



Plate 2. 



Cyrtoplax spinidentata, male type, X 1^. 



Fig. 1. Antero-veutral view. 



2. Dorsal view. 



3. Posterior view. 



Plate 3. 



Planes manniis, male type, X 2. 



Fig. 1. Antero- ventral "view. 



2. Dorsal view. _y 



3. Ventral view. 



Plate 4. 



Cyrtograpsus altimanus, X 2. 



Fig. 1. Ventral view of male type. 



2. Dorsal view of male type. 



3. Antero- ventral view of male paratype. 



Plate 5. 

 Platychirograpsus typicus, dorsal view of male type, nat. size. 



