A HISTOEY OF EECENT CEUSTACEA 



Nannoniscus, Sars, 1869, has the head produced into a 

 frontal process, the pleon consisting of a single piece, sub- 

 triangular, apically rounded or truncate. There are no eyes. 

 The mandibles have ten spines in the spine-row, the molar 

 short and narrow, the ' palp ' short, three-jointed. The 

 -operculum of the pleon is short, armed with a tooth ; the 

 uropods are very short, two-branched, with the inner branch 

 the longer, or they are single-branched. The type, Nann- 

 oniscus oUongus, Sars, a twelfth of an inch long, was 

 taken at depths between 120 and 250 fathoms. It is de- 

 scribed as having on the short three-jointed first antennas 

 ' a single ovoid olfactory papilla of portentous size.' A 

 second species, Nannoniscus bicuspis, Sars, has the first 

 antennas seven-jointed, the second pair forming on the 

 outer side a large triangular process. This species has the 

 uropods simple, biarticulate. 



Eugerda, Meinert, 1890, has the last three segments of 

 the perason longer than the anterior segments, the pleon- 

 segments fused into one. The mandibles are without 

 molar and ' palp.' The maxillipeds have the first three 

 joints of the ' palp ' broad, the last two narrow and small. 

 All the limbs of the peraeon are long, the first pair more 

 slender and smooth than the rest. The opercular plate of 

 the pleon is orbicular; the uropods are moderately long, the 

 branches single-jointed, the inner the longer. Eugerda 

 globiceps is the type. 



Dendrotion, Sars, 1871, has the head divided into two 

 ear-like branches, to which the two pairs of antennas are 

 attached. The first four segments of the perason have each 

 a long spine on either side ; the three following segments 

 are abruptly much narrower. The pleon has all the seg- 

 ments fused into one. There are no eyes. The mandibles 

 have a conical molar, the ' palp ' three-jointed, The first 

 limbs of the peraeon are shorter than the others, which are 

 long and slender. There are no uropods. 



Macrostylis, Sars, 1864, has the first three segments of 

 the perason so closely united as to give an appearance of 

 fusion, the four following segments being very distinct, 

 with acute postero-lateral angles. The pleon forms a long 



