EEPOET ON THE ISOPODA. 53 



Munnopsis australis, F. E. Beddard (PL XIII. figs. 1-11). 



Munnopsis australis, F. E. Beddard, Proc. Zool. Soc. Loitd., 1885, pt. iv. p. 917. 



This species, of which I have been able to study a single example mounted on a slide 

 in Canada balsam, agrees with Munnopsis typica in that the three posterior segments of 

 the thorax are considerably narrower than those which precede them ; Munnopsis 

 australis is in other respects not very dissimilar from Munnopsis typica. The present 

 specimen is a female, and was dredged from 1600 fathoms between Prince Edward's 

 Island and the Crozets. 



It measures 8 mm. in length, exclusive of course of the enormously elongated 

 antennae, which measure themselves at least 36 mm. 



The head is comparatively narrow in proportion to its length ; its general outline is 

 in fact oval, though the anterior margin is straight and abruptly truncated ; the region 

 between the insertion of the antennas is very wide, quite as much so as in Munnopsis 

 latifrons and Munnopsis typica; a semicircular process extending a little over the 

 articulation of the antennules on each side is shown on fig. 1. 



The first segment of the thorax is extremely narrow especially dorsally ; it widens out 

 laterally to nearly the width of the succeeding segments of the thorax ; the segment 

 closely embraces the head, and is in consequence almost V-shaped, the concavity being of 

 course anterior ; the second segment of the thorax is five or six times as long as the first 

 and subequal to the two next ; at the second segment the body of this species is broadest, 

 gradually decreasing in breadth both before and after this segment ; the shape of the 

 thoracic segments gradually alters from the first to the fourth ; the V-shaped form so 

 conspicuous in the first becomes less and less marked in the remaining segments, the 

 fourth being almost straight, with sub-parallel anterior and posterior margins. 



All the segments of the thorax are furnished with epimera which, although visible on 

 a dorsal view of the animal, are not large ; their margins are not prolonged into spiny 

 processes as they so often are in the species of this family. The remaining segments of the 

 thorax, together with the caudal shield, form a narrow cylindrical section of the body which 

 contrasts very much in this respect with the anterior region, being not more than perhaps 

 one-half its width ; the three segments of the thorax, although about equal in width, differ 

 very much from each other in length, that is to say, the anterior segment differs very much 

 from the sixth and seventh ; it measures at least three times the length of either of these, 

 which are both short and subequal ; I am not certain as to the lines of demarcation between 

 these latter segments, which I could not detect in the specimen. 



The abdominal shield is long and narrow and has very much the form of the abdominal 

 shield in Idothea. It terminates posteriorly in a somewhat conical process which is 

 upturned ; the upper surface appears to be regularly convex. 



It has been already stated that the present specimen is a female ; the identification of 



