i66 Records of the Indian Museum. [Vor,. XXIV, 



(iv) The merus of the second leg is equal to or slightly longer 

 than the ischium and does not bear a spine at the distal end of 

 its lower border. 



( v) The fingers of the second leg are only one-third the length of 

 the palm. 



(vi) The lower border of the merus of the last three legs does 

 not end in a tooth. 



(vii) The dactylus of the last three legs is provided with a 

 small accessory spine and is only one-ninth the length of the 

 propodite. 



P. soror was described from Djibouti in the Red Sea. 



Periclimpnes (Periclimenes) commensaiis Borradaile. 



1915. Perclimenes (Cristiger) commensaiis, Borradaile, Ann. Mag. 

 Nat. Hist. (8) XV, p. 21 r. 



1915. Periclimenes commensaiis, Potts, Publ. Carnegie Inst. Washing- 

 ton, no. 212, p. 82. 



191 7. Periclimenes (Cristiger) commensaiis, Borradaile, Trans. Linn. 

 Soc. (2) Zool. XVII, p. 364. 



I have examined the type of this species and think that 

 Borradaile is mistaken in stating that there are two spines at the 

 distal end of the basal antennular segment. The margin between 

 the outer spine and the articulation of the second segment is some- 

 what more produced than usual, but is rounded and does not end 

 in a spine. P. frater, Borradaile, which I refer to the subgenus 

 Ancylocaris, appears to be the only species of the genus in which 

 two spines occur in this position. 



The accessory tooth on the dactyli of the last three peraeo- 

 pods is small and inconspicuous in this species. 



P. commensaiis was found by Mr. Potts on Comanthus annu- 

 laris at the Murray Is., Torres Straits. 



Subgenus Periclimenaeus Borradaile. 



1915. Periclimenaeus, Borradaile, Ann. Mag. Nat. Hist. (8) XV, p. 



207. 



1916. Periclimenes subgen. Hamiger, Borradaile, Brit. Antarct. Exped. 



1910, Zool. Ill, p. 87. 



1917. Periclimenaeus, Borradaile, Trans, Linn. Soc. (2) Zool. XVII. 



P- 377- 



The species of this subgenus resemble those of Periclimenes 

 s.s. in having the dactyli of the last three peraeopods biunguiculate, 

 but differ in the absence of the hepatic spine of the carapace. The 

 second peraeopods are unequal and dissimilar and the chela of the 

 larger limb is always very massive. 



The status of the subgenus is precarious. The three species 

 referred to it appear to form a natural group, but the only un- 

 equivocal point of distinction from Periclimenes s.s. is the absence 

 of the hepatic spine. If, as is not improbable, a species is dis- 

 covered which lacks this spine, but possesses affinities with Peri- 

 climenes s.s. rather than with Periclimenaeus , the latter subgenus 



