152 BULLETIN 97, UNITED STATES NATIONAL MUSEUM. 



Diagnosis. Carapace uneven. Two short ridges on cardiac region. 

 Fingers of male widely gaping. Dactyli of first two legs slightly 

 curved, of last two straight. 



Description of male. Surface densely pubescent and hairy, espe- 

 cially on chelipeds and margins of carapace and legs. Regions and 

 their subdivisions well limited; subbranchial re- 

 gi n advanced, forming a prominent shoulder 

 with granulated edge ; lateral angle a right angle ; 

 a submarginal groove parallel to posterior and 

 postero-lateral margins; on each side of cardiac 

 FIG. 93. I'IXXIXA region a short sharp ridge arched upward; a few 

 cHAEToi-TEKAXA, g ranu l e s on antero-lateral margin; front little 



BUZZAUDS BAY. a, .. 



CHELA or ADULT advanced, truncate. 



FEMALE, x G; b, Chelipeds strong, smooth ; palm very wide, con- 



CHELA OF ADUI.T ' L J ' 



MALE, x 4. (AFTEE vex on margins except near base of fixed finger, 



FAXOX -> which is very short, much deflexed, with a strong, 



triangular, prehensile tooth near its base and an obliquely truncate, 

 notched tip; dactylus strongly curved, almost vertical and forming 

 an oval gape when closed. 



Dactyli of first two legs slender and slightly curved, of last two, 

 stout and nearly straight; first and second legs slender and of nearly 

 same size, second reaching to end of propodus of third; third stout, 

 merus about twice as 

 long as wide, nearly 

 straight above, dis- 

 tally narrowed, pos- 

 terior margin, as 

 well as that of pro- 

 p o d u s, spinulous ; 

 fourth leg of similar 

 build, reaching to 

 middle of carpus of 

 third. 



Sixth segment of (\~S\ f 



abdomen constricted a b 



at middle, seventh FIG. 94. PINNIXA CHAETOPTERAXA (5043). a, OUTER MAXIL- 

 <;pmirirrMil'ir LIFED OF FEMALE, X 17 ; 6, ABDOMEN OF MALE, X C|. 



Sexual variation. Carapace more swollen in female, fingers mod- 

 erately deflexed, not gaping, thumb longer and stouter, a small 

 tooth at each end of truncate extremity, no subbasal tooth, a small 

 tooth on dactylus behind middle. 



Measurements. Male (5043), length of carapace 6.3, width of same 

 14mm. Female (18289), length of carapace 6.3, width of same 14 mm. 



Habitat. Commensal in tubes of annelids, Amphitrite ornata and 

 Chaetopterus pergamentaceus "whose parchment-like sheath, ex- 



