South African Crustacea. 85 



EURYSTHEUS HOLMESI, n. Sp. 



Plate XL.A. 



Fourth pleon segment dorsally tridentate, the median tooth smaller 

 than the others, fifth segment with a dorso-lateral tooth on each 

 side. Head with lateral lobes not strongly produced, the apex acute. 

 First side-plate produced a little forwards, second to fourth with 

 lower angles rounded, fifth as deep as fourth in front, its hind lobe 

 shallow, sixth also bilobed with smooth lower margins. First to 

 third pleon segments with postero-lateral angles produced to a small 

 point. 



Eyes red (in spirit), placed close to apex of the lateral lobes of the 

 head. First antenna with stout first joint, shorter than second, 

 equal in length to the third ; accessory flagellum 6-jointed, rather 

 longer than third joint of peduncle, principal flagellum imperfect. 

 Second antenna with fourth and fifth joints subequal, each shorter 

 than the 10-jointed flagellum. 



Mouth-organs characteristic of the genus. Epistome pointed. 

 Mandibular palp with 3rd joint widened, setose. Inner plate of 

 first maxilla apparently with few setae. Fourth joint of palp in the 

 maxillipeds narrow. 



First gnathopod slight in structure, 5th joint a little longer than 

 the somewhat fusiform 6th. Finger in the specimen examined 

 apparently dwarfed and malformed on one gnathopod, both hand 

 and finger missing on the other by mutilation. 



Second gnathopod large and powerful. The second joint not very 

 elongate, channeled in front, fourth short, oblong, fifth cup-shaped, 

 on the outer side very short, and not very long on the inner, sixth 

 muscular, much longer than broad, front margin smooth, hind 

 short, carrying slender spines at five points and ending in a tooth, 

 which is slightly overlapped by the apex of the elongate finger. 

 The long palm from a smooth curve near the finger-hinge develops a 

 tooth followed after a short interval by one less large, and after a 

 longer interval by a third more prominent, whence a long slope 

 leads to the small palm-defining tooth. The finger on the proximal 

 half of its inner margin has four or five minute teeth or serrations. 



The first and second peraeopods are of the usual form, with cement 

 glands well developed. The third and fifth pairs are much shorter 

 than the fourth, all three being distinguished in the second joint by 

 the irregular denticulation of the hind margin, which is slightly 

 sinuous in the fourth and fifth pairs, but forms a strongly produced 

 lobe proximally in the third pair. 



