394 Mr. W. N. Lockington on the PorceUanidea 



The accompanying list of PorceUanidea (which includes de- 

 scriptions of nine species I believe to be new, since they are 

 certainly distinct from any of those described or mentioned by 

 Stimpson as found upon this coast) does not profess to be 

 complete, but merely to give facts of distribution and other 

 particulars respecting forms with which I am acquainted. 



Stimpson, in his '■ Prodr. des Anim. dvert.' 1858, divides 

 the old genus Porcellana into the following genera : — Petro- 

 listhesj Pisosoma, Raiyhidopus^ Pacliyclieles^ MegalohracMum^ 

 Porcellana^ Minyocerus, Porcellanella (White) , and Polyonyx. 



In the first two of these the first joint of the antennal base 

 is short, not reaching the margin of the carapax ; while in all 

 the others the first joint is more or less produced, and joined 

 to the margin of the carapax. 



The more convex carapax, stouter chelipeds, and less pro- 

 jecting front are the characters which separate Pisosoma from 

 Petrol Isthes] but as some of my species have some of the cha- 

 racters of the former genus, while they are Avithout others, I 

 find it exceedingly difiicult to discriminate. I have therefore 

 included Pisosoma in Petrol ist lies, placing the former name in 

 brackets before the specific names of such species as, in my 



