i88 Memoirs of the Indian Museum. [Voi,. IV, 



This species along with the four following is easily distinguished from the others 

 in the section (i.e. species 12-20) by the very wide median excavation in the distal 

 margin of the telson. 



The carapace is broader behind than in front and, at its narrowest, is about two- 

 thirds the median length. The posterior margin and the anterior margins on either side 

 of the rostral base are slightly concave ; the antero-lateral angles are produced and 

 subacute. The rostrum is sharply trispinous; the median spine reaches as far as the 

 corneal portion of the eyes ; those of the lateral pair are much shorter and rather 

 stouter. The basal part of the rostrum is extremely short, little if at all longer than 

 one quarter the length of the median spine. 



The dorsal processes of the ophthalmic somite have much the same form as in 

 G. glaber. The eyes reach to about the middle of the second segment of the antennular 

 peduncle ; they measure one-third the median length of the carapace in large specimens, 

 but are longer in small examples. They differ from those of the preceding species in 

 being distinctly flattened and the cornea, seen in dorso-lateral view, is set transversely 

 on the stalk. The mandibular palp is composed of two segments. 



The basal part of the dactylus of the raptorial claw is greatly inflated and its ex- 

 ternal margin is notched proximally, as in G . glaber. 



The margins of the sixth and seventh thoracic somites are truncate with rounded 

 anterior and posterior angles. The median portions of the first five abdominal somites 

 are entirely smooth, but each possesses laterally the L-shaped ridge noticed in the 

 preceding species ; the postero-lateral angles of the first three are rounded , those of 

 the fourth subacute, while those of the fifth are strongly produced and spinous. In 

 the fifth there is a rather deep furrow on either side which runs to the extreme distal 

 edge of the somite, external to a small rounded lobe on the posterior margin. The sixth 

 somite bears three pairs of smooth elevations ; the innermost are the shortest, those of 

 the intermediate pair are constricted in the middle, while the outermost, which are the 

 longest, meet the external margin in an obtuse postero-lateral angle. 



The telson is about as long as wide. The three mid-dorsal bosses are similar to 

 those of G. glaber, but the median one is longer and is entirely separated by grooves 

 from the two laterals. The outline of these prominences is not even : the edges of each 

 are furrowed and eroded. As in the preceding species there is a strong rounded keel run- 

 ning along the lateral margins. Distally there is a wide and deep triangular excavation, 

 which bears on its edges numerous (about twelve) small denticles. This excavation 

 forms a sharp contrast with the very narrow median fissure found in the preceding 

 species. On either side of this gap there are two small tooth-like lobes, the inner more 

 acute than the outer, and between each pair of lobes there are one or two small 

 denticles. 



The inner spine of the bifurcate process of the uropod is more than half the length 

 of the outer, and on the external margin of the basal segment of the exopod there is a 

 series of nine to eleven movable spines. 



A few of the specimens are, in spirit, densely mottled with dark pigment on the 

 carapace and first five abdominal segments ; the other examples are faintly speckled 

 or colourless. 



