

BY WILLIAM A. HASWELL, M.A., B.SC. 679 



The male (pi. XXXVI., fig. 2) differs greatly in appearance 

 from the female. It is extremely attenuated, the length being 

 half an inch and the breadth only ^th of an inch, the thoracic 

 segments being extremely elongated and slender. The limbs are 

 very small and feeble, but are similar in structure to tho.se of the 

 female. 



In the form of the body and of the pleonal appendages this 

 curious genus presents a very marked approximation to the 

 Anthuridce ; it is distinguished from these, however, not only by 

 the anterior pereiopoda being simple, but also, is would seem, by 

 ihe position of the embryo in the egg, the flexure in the present 

 form being towards the dorsal side, as in the " normal " Isopoda of 

 Spence Bate and YvVstwood, wheieas in the Anthuridit the 

 flexure of the embryo is towards the ventral side. I am inclined, 

 however, especially as the development of so few of the Anthuridce 

 lias been studied, to attribute less weight to the latter point, and 

 am disposed to think that the structure of the appendages and the 

 form of the body ally Eisothistos most nearly with the Anthurida , 

 though with some points of resemblance to the ^Egidce. 



EXPLANATION OF THE PLATES. 



Plate 36. 

 Fig. 1. — Female of Eisothistos rtrmijbnnis, xl2. 

 Fig. 2.— Male (?) of the same, xl2. 

 Fig. 3. — Posterior extremity of the same from above with the terminal 



appendages opened, p, ramus of posterior appendages ; t, telson. 

 Fig. 4. — Anterior antennae.. 

 Fig. 5. — Posterior antennas. 

 Fig. 6. — Second pair of pereiopoda. 

 Fig. 7. — Apex of one of the more highly magnified. 



Plate 37. 

 Fig. 1. — Posterior extremity from below, t, telson ; p, ramus of posterisr 



pleopoda ; p\ appendage ; a, anterior pleopoda. 

 Fig. 2. — Dursal plate of the first segment. 

 Fig. 3. — Ventral plate of one of the middle segments. 



