408 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 5 



2. The orbital horns of both species are divergent, although less 

 strongly so in T. lamellifrons, and in both they extend beyond the rostral 

 horns. Lines drawn through their long axes would cross at the gastric 

 level in emarginata and at the cardiac level in lamellifrons because of the 

 more divergent angle taken by them in the former species. 



3. The posterior margin of the carapace of lamellifrons is faintly 

 trilobate, that of emarginata strongly bilobate and lamellate. 



4. Because of these posterior lobes and the greater length of the 

 rostral and orbital horns, the proportion of length to breadth of carapace 

 appears greater in emarginata than in lamellifrons, particularly in adult 

 male specimens. 



5. The ambulatory legs of lamellifrons are shorter and stouter than 

 those of emarginata. 



6. The exopodite of the third maxilliped of emarginata has a basal 

 protuberance which recurves to cover the base of the ischium. The merus 

 inserts deeply into the outer distal portion of the ischium by a similar, 

 but less developed tongue or flange. The inner margin of the ischium is 

 strongly dentate. (See text fig. 1.) 



In lamellifrons the basal projection of the exopodite does not recurve 

 to cover the base of the ischium, the merus does not insert so deeply into 

 the ischium, the inner margin of which is nondentate. 



7. The first free antennal segment in lamellifrons is flattened, in 

 emarginata it is cylindrical. 



8. The sternal plastron of emarginata is deeply indented and there 

 are 2 strong tubercles, one on either side of the base of the last abdominal 

 segment in the male. The sternum of lamellifrons is flat with but a slight 

 tubercle opposite the last abdominal segment. 



T. lamellifrons is now recorded from the Galapagos Islands. 



