298 On the Classification of the Crustacea Choristopeda. 
mediate forms and are naturally arranged in a separate group. ‘These 
constitute the tribe here named 
The Anisopopa. 
1. Like Amphipoda, the three posterior gairs of thorwese Jegs are in 
one series, and the four anterior in a diffe rent series or usually in 
sets of two pairs each ;—4(or 2 
2, Like®Tsopoda, the three posterior pairs of abdominal members a 
stylifurm, only the last pair being of this character; the eich 
organs are abdominal and not thoracic, with a rare exception. 
These are constant characteristics of the whole group. Although 
dienety Aushigoden, the aera have in general more external oa 
semblance to the Isopods; yet the intermediate character of so 
genera is so obvious thai they have been be since. in the former poor 
by one author and in the latier by anot 
The genera that pertain to this tribe, nikcyadey are the following: 
Arcturus and the allied Anthura, Tanais, Apseudes, Rhea, Praniza, 
Anceus, Serolis Pre esc age allied. Each of the larger subdivisions of 
the [sopoda, as laid y Edwards, affords one or more genera, and 
they are genera whieh it in rd system are in some instances marked off 
as anomalous in charact “ee 
In Arcturus and Anthura, the thoracic members have the Amphipod 
character, the series being 4 (or 24+2) : 8, and not 2: 4.as in the Isopods. 
e abdominal appendages are like those of [dota 
In Tanais, there is the same arrangement. The nebdouinl ae 
ages are Isopodan in being characierized by the series 5:1, eo 
The ah 
and di fore from the Amphipodan abdom mainly in having but one 
pair of stylets with 5 pairs of sabitarstageid ‘instead of three of stylets 
Praniza and Anceus have the thoracic legs Amphipodan ia their ar- 
rangement. The abdomen in Praniza is considerably elongated and 
flexible, speromening the Amphipodan; but the arrangement of its ap- 
pepe s 1s lsopoda 
In Serolis, ziaagh the general aspect of the £yeme is strikingly 
Isopodan, the arrangement of the thoracic legs is Amphipodan. re 
ther than this, the abdomen is partly Amphipodan, for instead of ” 
series 5: 1, it has the series'3:3; yet while the 3 anterior pairs are 
natatory as in the Amphipuda, the next two, instead of being styliform, 
like the last, are —— (one opercular to the other), and in this pat 
ticular they are Isopodan. 
In the Bopyri, the thoracic legs are so arranged ina oo continu- 
ous series, that it is difficult to make out the series 4:98 or 
some figures, the former (ihe Amphipodan) arrangement, is s indicated. 
The males are closely like Tanais-in some instances, = bork 16 n the length : 
* Seo Krsyer in Voy. Scand, pl 9fig VA, Dae Mei aaa oe 
