260 CAEL BOVALLIUS, AMPHIPODA HYPERIIDEA. I. 2. HYPERIIDJE. 



Parathemisto japonica. 



The first pair of maxillce (PI. XII, fig. 28) have the same form as in the genus 

 Hyperia. The basal joint is very short and almost globular; the principal lamina is long, 

 with the basal portion nearly rectangular; the apical portion forms a feebly curved and 

 concave process, densely covered with long bristles, and provided at the apex with two 

 long, and four somewhat shorter, stout spines. The secondary lamina is tolerably narrow, 

 and fully as long as the stem of the principal lamina; the inner margin is serrated, and 

 at the apex there is a row of short bristles and a single, curved, strong spine. 



The second pair of maxilla} (PI. XII, fig. 29). The principal lamina has the basal 

 portion broad; the apical projecting portion is nearly cylindrical, with the apex rounded, 

 and provided with a single stout spine and some tufts of long bristles. The secondary 

 lamina is broader, with the apex rounded, and covered with long hair-like bristles. 



The maxillipeds (Pi. XII, fig. 30) have the basal portion broad, with feebly concave 

 margins; the lateral laminae are bean-shaped, the outer side being convex and the inner 

 concave; the outer margin is strongly convex, and smooth, the inner is feebly concave 

 or nearly straight, notched, and armed with long bristles. The median lobe is strongly 

 projecting inwards, much longer than in the genus Hyperia; the broad apex is armed 

 with two short spines, and is thickly covered with bristles. 



The peraion. The median keel on the dorsal side is neatly defined, but does not 

 project at the hind corners of the segments into processes. The first segment is longer 

 than the second, and almost as long as the sixth or seventh. 



The epimerals are somewhat longer than the under margins of the corresponding 

 segments, longer than deep, and have the corners rounded. 



The branchial sacks are ovate, and a little shorter than the femora of the cor- 

 responding pairs of perseopoda. 



The first pair of peraiopoda (PI. XII, fig. 31 and 32) are considerably shorter than 

 the second pair. The femur is about as long as the four following joints together, 

 broader above than below, and has an unusually broad groove on the front margin for 

 the reception of the next joints. The genu is broader than long, and is fringed on the 

 hind part of the under margin with long bristles. The tibia is a little longer than the 

 genu, with the under margin fringed with long bristles at the hind corner. The carpus 

 is tolerably broad, scarcely more than one-third longer than broad; the front margin is 

 feebly convex, and fringed with five or six long bristles; the hind margin is notched, and 

 densely set with longer and shorter stout bristles; the free part of the under margin is 

 obliquely truncated, and armed with bristles. The metacarpus is as long as the carpus, 

 broad at the base, tapering towards the apex, with bulging sides; the strongly convex 

 front margin is fringed with eight or ten long bristles; the hind margin is serrated with 

 long, simple, spine-like teeth, and a few equidistant, short bristles. The dactyl us is 

 curved, quite half as long as the metacarpus, and somewhat rugose, but not serrated, on 

 the hind margin (PI. XII, fig. 32). 



The second pair (PI. XII, fig. 33 and 34) reach nearly to the apex of the carpus 

 of the third pair. The femur is considerably longer than that in the first pair, and 

 about as long as the four following joints together; the front margin is almost straight, 

 the hind is feebly convex. The genu is broader than long, with half a dozen long bristles 



