154 



DISCOVERY REPORTS 



segments gradually increasing in length. First 4 side-plates deeper than their segments ; 

 1st largest, triangularly produced forwards, 2 a trifle deeper than 1, 3 narrow like the 

 2nd but a little shallower, 4 shallower than 3, inferior margin oblique, almost straight, 

 posterior margin shallowly concave; side-plates 5-7 shallow, feebly bilobed. Pleon 

 segments 1-3 longer than any of the peraeon segments, dorsally rounded, postero- 

 inferior angle of 2 quadrate, of 3 somewhat produced backwards, but the actual angle 

 quadrate, not acute. Pleon segment 4 dorsally with basal notch, followed by a medio- 

 dorsal keel which ends abruptly. Telson longer than broad, narrowing slightly distally, 

 apex emarginate between the subacute postero-lateral angles. 



Fig. 90. Cacao lacteus, Brnrd. a. Head and peraeon segments 1-5 with side-plates and bases of antennae 1 

 and 2. b. Lower lip. c. Left mandible, d. Maxilla 1. e. Maxilla 2. /. Maxilliped. g. Gnathopod 1. /;. 

 Gnathopod 2. i. Peraeopod 2. j. Peraeopod 5, with anterior margin of 6th joint further enlarged, k. Telson. 



Antenna 1 reaching back to about end of peraeon, 1st joint moderately stout, flagellum 

 about 48-jointed, no accessory flagellum, lower margin of peduncle and basal joints of 

 flagellum rather densely setose, especially in <$ . Antenna 2 a little longer than antenna 1, 

 flagellum about 58-jointed, upper margins of 3rd~5th peduncular joints setose, the 

 setae shorter than in antenna 1, and in the <$ arranged in numerous fascicles. 



Upper lip asymmetrically bilobed. Mandible broad, thin, cutting edge smooth, 

 secondary cutting plate in left mandible only, large, transversely elongate, its margin 

 dentate, palp with 3rd joint shorter than 2nd, no spine row or molar. Lower lip, inner 

 lobes obsolete or quite rudimentary, outer lobes acuminate. Maxilla 1, both lobes pro- 

 jecting inwards, inner lobe much smaller than outer, which has a series of 15 evenly 

 spaced spines on its inner margin and a dense brush of short spine-setae at the inner 

 proximal corner, palp with 1st joint small, and joint enormously expanded into a sub- 



