24 Descriptio7i of Genera and Species. 



Tkalliocaris robusta sp. nov. PI. III., figs. 5-8. 



Specific Characters. — Strong robust form. Length, 30-40 nnn. Integuments firm 

 and ornamanted with pits, and granulated. The seven keels of the carapace crenulated. 

 No ocular spine, but a blunt one at the anterior angle of carapace. A slight peak 

 backwards in the mid-line of the posterior margin of the carapace suggestive of a 

 median spine. Longitudinal ridges of tlie tail very marked and sharp and crenulated 

 on the hindermost segment and telson. 



General Description. — This species strongly resembles T. wood war cii,es\)eclall\ in the 

 distribution of its longitudinal keels on the carapace and the longitudinal ridges on the 

 tail, but differs from it in its much greater size and more robust proportions. It is 

 altogether more strongly built and its integuments are more embossed and its longitudinal 

 keels and transverse bands deeper and broader, and the keels are distinctly crenulated 

 alono- their crests. A cast of the interior of the carapace is illustrated by fig. 5, M. 2752"^, 

 which, though it has been torn in two before being embedded, shows its characters well, 

 viz., its great width compared with the length, the seven crenulated longitudinal keels 

 behind the well-marked cervical fold, the blunt inwardly-directed spines at the antero- 

 lateral angles, the absence of an ocular spine, the rostrum, relatively wider at base than in 

 the already described species, but surmounted by the sharp crest of the ridge keel, and the 

 backward peak in the mid-line of the posterior margin. All these features are also shown 

 in fi"'. 6, which is a drawing of the inside of the carapace, the peak in the mid-line of the 

 posterior margin being even more suggestive of a blunt spine than in the former one. 

 The tail segments and part of the telson flanked by the uropods are shown in fig. 8 

 enlarged about 3 diameters. The details are much like those of T. iroodwardi, but 

 with every structure exaggerated. The strong transverse bands, rising abrupt!}' from the 

 rollino- facets to ensure locking of the tail joints when that organ was extended, the strong 

 and backvrardly-set epimera, and the median and lateral keels, as well as the embossed 

 panel-like compartments confined within these structures, are all suggestive of great 

 muscular power. A view of the underside of part of the trunk and tail is afforded by 

 the specimen shown in fig. 7. At the anterior end two joints of the peduncle of the 

 ri^'ht antennule are seen partly covered by portions of the antennal scale, as well as the 

 peduncle and part of the massive antennal lash. The broad sternum, narrowing in front 

 and showing parts of at least seven segments, is well displayed with the bases of four of the 

 limbs still articulated with it on the right side of the animal, and one on the left. The 

 terminal joints of two of the exopodites and the'basal joint and lash of one of the exopo- 



