52 NOTES ON TASMANIAN CEUSTACEA, ETC. 



tails may be added here, but I propose elsewhere to describe 

 the animal more fully, and. to discuss its affinities. 



The cephalon is hardly larger than any of the body segments, 

 and is produced in a very short acute rostrum between the 

 bases of the antennae ; its sides are sub-equal in depth to the 

 succeeding segments. The first thoracic segment alone has 

 its sides divided bv a very distinct and somewhat oblique 

 line into a broad epimeron ; none of the other segments bear 

 any traces of epimera. The lateral margins of all the thoracic 

 segments but the last are more or less covered by the plate- 

 like branchiae of their respective segments, which are all ex- 

 ternal to the body and projoct forwards. The abdominal 

 segments are somewhat longer than the thoracic; their mar- 

 gins are smooth, except the two last, which are slightly fringed 

 with short tooth-like spines or setae. 



The cephalic segment carries the ophthalmites, two pairs of 

 antennae, the mandibles, and two pairs of maxillae. The first 

 thoracic segment carries the first pair of walking legs, which, 

 are the modified maxillipeds. Each of the succeeding seg- 

 ments bears a pair of appendages, those of the thorax acting 

 partly as walking legs and partly as natatory organs, 

 and those of the abdomen as natatory organs. The 

 telson is bluntly triangular in form, slightly ridged down the 

 median line and thickened along its outer margins ; the pos- 

 terior rounded margin is fuimished with a comb-like row of 

 short spines. 



The eye-peduncles are short, one-jointed, and directed 

 obliquely outwards. The antennae of the first pair have a three- 

 jointed peduncle, the joints of which are broad and rather 

 flattened. The last joint bears two flagella, the outer of which, 

 is composed of a great number of articulations — usually 

 from 75 to 100 — and is from two-thirds to three-fourths the 

 length of the whole animal ; the inner is less than one-fourth 

 the length of the animal, and is divided into from 20 to 25 

 articulations only. The second antennai have a four- jointed 

 peduncle, with a long multi-articulate (50-60 joints) flagel- 

 lum, the first joint of which is probably, however, to be 

 reckoned as the fifth of the peduncle. The moveable plate 

 at the end of the second joint is oval, and has a smooth mar- 

 gin fringed with long j)lumose setae. The flagellum is about 

 two-thirds as long as the body of the animal. 



The mandibles are strongly developed and are placed so as 

 to close the mouth opening with their exposed part. The 

 cutting edge is furnished with a double row of strongly in- 

 durated teeth, and at right angles to it stands the large oval 

 grinding tubercle. The first maxillas slyb two-branched ouly, 

 the outer branch ending in a double row of strong spines 

 which are pectinately toothed on the inner side, and the inner 



