50 carcinological studies. 



1. Car pilodes tristis Daua. 



Carpilüdes tristis, Dana, United States Exploring Expedition, 

 Crustacea, T. I, p. 193, PI. IX, fig. 7. 



One male from Tahiti. 



The nearest ally of this species is Carpilodes laevis A. 

 Milne Edwards. Of this latter form I have before me a 

 male specimen from Amboina, which I have described 

 two years ago (Archiv f. Naturgeschichte , Jahrg. LIII , 

 p. 236), and so I am able to indicate the differences. 

 Unfortunately the cephalothorax of the specimen of tristis 

 is somewhat asymmetric posteriorly, which is probably caused 

 by a parasite in the left postero-lateral region of the carapace. 



The cephalothorax of Carpil. tristis is a little more 

 enlarged than that of the other species. The interregional 

 grooves are somewhat more distinct; therefore the urogastric 

 areola 4 M is already visible to the naked eye, which is 

 not the case in Carpil. laevis. The posterior of the two 

 grooves which border the third lobe of the antero-lateral 

 margins , is considerably longer in Carpil. tristis , 

 so that an imaginary line, which unites the extremities 

 of these grooves, coincides with the posterior border of 

 the areola urogastrica. The whole upper surface of the 

 cephalothorax of tristis proves to be very minutely granulated 

 when examined under a strong magnify ing-glass, but when 

 Carpil. laevis is observed under the same lens, this minute 

 granulation is only seen on the front and close to the 

 antero-lateral margins. 



The legs of Carpil. tristis are shorter in propor- 

 tion to the width of the cephalothorax, and the 

 ambulatory legs especially have a less slender 

 form. Thus e. g. the last pair of legs of Carpil. laevis 

 are about as long as the breadth of the cephalothorax , 

 measured at the incisions between the second and the third 

 lobe of the antero-lateral margins ; the posterior legs of 

 Carpil. tristis are, however, much shorter than that distance. 



X^otes from the Leydon IMuseiiixi, ^''ol. XII 



