1922.] W. M. Tattersall : Indian Mysidacea. 475 



developed than in Prionomysis, being present on the second, third 

 and fourth joints and very much larger. 



In addition to the form of the second maxilla, Prionomysis 

 also differs from Afromysis in the less specialized form of the fourth 

 pleopod of the male. 



Prionomysis stenolepis, sp. nov. 

 Text-figs. i6a-j. 



Locality. — Port Blair, Andaman Isles, Station 3. Eight 

 females, two males, 8-9 mm. (Types.) 



Description. — Carapace produced in front in the form of a 

 triangular plate with acutely pointed somewhat depressed apex 

 which reaches forward almost to the middle of the first joint of 

 the antennular peduncle ; antero-lateral corners rounded ; last 

 two thoracic somites exposed dorsally. 



Eyes large, somewhat flattened , cornea wider than the remain- 

 der of the eye, occupying more than one half of the eye in dorsal 

 view, the anterior margin of the eye stalk longer than the pos- 

 terior; eye at least as long as the first joint of the antennular 

 peduncle. 



Antennular peduncle with the first joint longer than the 

 remaining two combined ; the last joint in the male with a well- 

 developed hirsute lobe of normal form. 



Antennal scale exceedingly long and narrow and curiously 

 twisted, about thirteen times as long as broad, twice as long as 

 the antennular peduncle and four times as long as the antennal 

 peduncle, setose all round, terminal joint distinct though small. 

 Antennal peduncle much shorter than the antennular, second joint 

 'onger than the third; mouth-parts agreeing on the whole with 

 those of Afromysis hansoni Zimmer, except that the terminal 

 joint of the palp of the second maxilla is not expanded and produ- 

 ced into a narrow process but is normal in shape. 



First thoracic limbs robust, masticatory lobe present only on 

 the second joint and not nearly so well developed as in Afromysis 

 or Doxomysis, nail robust; second thoracic limbs having the nail 

 long and stout ; tarsus of the remaining thoracic limbs three-jointed 

 and terminated by a long stout nail ; all the posterior thoracic 

 limbs appear to be similar in size and form. 



Fourth pleopod of the male with both endopod and exopod 

 six-jointed, but the exopod one quarter longer than the endopod ; 

 each of the last three joints bears a stout plumose spine ; the 

 fourth pleopod of the male is very like that in the genus Lepto- 

 tnysis and not nearly so specialized as in the genus Afromysis. 



Telson slightly shorter than the last somite of the abdomen 

 and not reaching very much beyond the statocyst of the uropod ; 

 lateral parts of the last abdominal somite produced rather acutely 

 at each side of the base of the telson ; telson much narrower than 

 the last abdominal somite, not quite twice as long as broad at the 

 base, narrowing gradually for almost three quarters of its length 



