PROCEEDINGS OF THE NATIONAL MUSEUM. 



TOL. 65 



KEY TO KNOWN ZOBAS. 



a^ Exopodite of antenna a well-formed segment with several hairs. 



b.* Basipodites of both first and second maxillipeds with pigment 



spots Sesarma cinerea. 



1).^ Basipodite of second maxilliped only with pigment spot, 



Sesarma reticulata, 

 a} Expodite of antenna reduced to a tubercle with a single hair. 



6.* Eyes large Planes minutus. 



&.' Elj-es small Pachygrapsus marmoratus. 



PIGMENTATION. 



The color of the pigment in each case is bhick in the contracted 

 condition and varies from black to reddish-brown to yellow in 

 expansion. 



p. minutus. 



S. cinerea. 



S. reticulata. 



Anterior rostral 



Interorbital 



Supracardiac 



Subcardiac 



Lateral to stomach 



Lateral to first abdominal segment 



Postero-ventral lobe 



Labriim 



Mandible 



Antenna 



Maxillule 



Basipodite first maxilliped 



Basipodite second maxilliped 



Dorso-lateral first abdominal segment 



Ventral first abdominal segment 



Ventro-lateral second abdominal segment. 

 Ventro-lateral third abdominal segment. . 

 Ventro-lateral fourth abdominal segment- 



Ventro-lateral fifth abdominal segment 



Telson 



+ 

 + 



+ 

 + 

 + 

 + 

 + 

 + 



+ 

 + 

 + 

 + 

 + 

 + 

 + 

 + 

 + 



+ 

 + 



+ 

 + 

 + 

 -f 

 -f 

 + 



4- 

 + 

 + 



+ 

 + 



+ 

 + 



1IETA5I0RPH0SIS. 



The metamorphosis of the family seems to follow the usual brach- 

 yuran formula. There are at least three zoeal stages and there are 

 probably five. Two megalops stages are described. Cano has de- 

 scribed the development of Pachygrapsus marmoratus up to the early 

 crab stage. 



PACHYGRAPSUS MARMORATUS (Fabricius). 



The development of this form has been described by Cano (1891). 

 He gives a series of figures that show more details than the descrip- 

 tion. Cano did not secure his stages by observed molting of known 

 stages and seems to have missed some of the zoeal stages entirely. 

 The zoea seems to resemble tliat of Planes very closely indeed and it 

 is difficult to distinguish them certainly from the description pub- 

 lished. Cano did not describe the pigmentation and thus one useful 



