EEPOET OX THE ISOPODA. 73 



known to me, while the epimera are all short and abruptly truncated, reaching in no case 

 beyond the lateral margins of the caudal shield. 



The cephalic shield terminates in front in a comparatively long rostrum ; liehiud, the 

 suture which separates it from the thoracic segment is incomplete in the middle line, and 

 for a space on either side of it extending to nearly as far as the level of the eyes ; the 

 cephalic shield as well as the rest of the body is quite smooth, and free from tubercles. 



Tliora.e. — The epimera of the first thoracic segment are entire and devoid of any trace 

 of a transverse suture ; the epimera of the remaining thoracic appendages are \evj short, 

 and have the appearance of being truncated at their free extremity; the anterior mai-gin 

 of the epimeron, instead of passing insensibly into the outer lateral margins, meets it almost 

 at right angles, and the outer margins run liackwards in a direction almost parallel to the 

 long axis of tlie body ; the epimera of the three anterior free thoracic segments are 

 separated by a distinct suture from their terga. The epimera are extremely short, as may 

 be seen in PI. VIII. figs. 1, 2, where this species is figured. The two last thoracic 

 segments have the same characters that are peculiar to the other Australian species 

 of the genus ; the tergum of the fifth is extremely narrow, not more than one-fourth 

 the breadth of the segment in front ; the tergum of the sixth segment is entirelv absent. 

 The sutures which separate both segments from the succeeding and preceding ones 

 entirely disappear close to the middle line of the body. 



The outer margins of all the thoracic epimera are faintly serrated. Veutrally the middle 

 portion of the segments is elevated into a broad ridge which becomes higher towards the 

 middle line, and slopes off gradually in the direction of the epimera ; in the sixth 

 segment this ridge is still more marked, and lieing develojied upon its posterior border 

 overlaps the terminal thoracic segment. The terminal segment of the thorax bears on 

 either side, close to and just above the attachment of the first abdominal limb, a circular 

 aperture which may l)e the outlet of some gland. I observed a similar pair of orifices 

 in Serolis i'>cdlida, and in several other species. 



Abdomen. — The epimera of the second and third alidominal segments extend as for 

 as the edge of the caudal shield ; the outer margin of the second is concave, that of the 

 third nearly straight. The ventral portion of the first three segments is furnished with 

 a central triangular keel which projects some way back as a stout conical spine ; the 

 spine is largest upon the first segment, and its cavity communicates with the exterior by 

 several large fenestras upon the lower surface (PI. VII. fig. 8). 



The caudal shield has a somewhat pentagonal outline, and terminates in an abrujitly 

 truncated extremity; the dorsal surface has a middle and two lateral carina); the portion 

 which lies beyond the latter is strongly bent down ; the posterolateral margins ai'e 

 slightly denticulate. 



Appendages. — The anteniue are displayed in figs. 9 and 10 of PL VII. The anterior 

 pair (fig. 9) are rather shorter than the second pair ; their terminal filament has thii'teen 



(ZOOL. CUALL. EXP. — PART XXXHI. — 1884.) I'^k 10 



