88 



structure of this carapace presents the following appearance : the ribs 

 are strongly marked and are somewhat prominent, the lower edge 

 being beaded or ornamented with a line of raised romid dots of a 

 rather regular figure. The surface between the ribs is sHghtly con- 

 cave, and is marked very distinctly with numerous raised dots or 

 punctations of a rather irregular form and size. 



Hab. Strasbourg, Hermann. Toulouse, Joly. Oran, M. Bravais. 

 Algeria, Lucas. Regency of Tunis, Mr. Frazer. Brit. Mus. 



That this is the Daphnia yigas of Hermaim I think there is no 

 doubt, and quite different from the Limnadia Hermanni of Bron- 

 gniart. The body of the Limnadia is entirely enclosed within a cara- 

 pace, regularly oval, transparent, and of a whitish colour. That of 

 the Daphnia gigas, according to Hermann, is enclosed within a cara- 

 pace of the colour of amber, horny, transparent, oval, with the back 

 gibbous, keeled, and edged with brown. The carapace of the Lim- 

 nadia is smooth, or offering only two or three zones parallel to its 

 free edge. That of the Daphnia gigas has 7 rings or parallel zones 

 on the two lower thirds of its body, and to judge from the figure 

 given by Hermann, has several more on the upper portion. In struc- 

 ture and form it thus agrees with the characters of the genus Estheria, 

 and appears to me to be perfectly identical with the Isaura Cycla- 

 doides of Joly. 



Sp. 2. Estheria Melitensis, Nobis. (PI. XI. f. 2, 2a, 2b, 2c.) 

 Carapace-valves of an elongated oval form, considerably narrower 

 at the posterior than the anterior extremity ; of a light horny colour, 

 and semitransparent. Anterior extremity rounded ; the beaks si- 

 tuate near that extremity and prominent, causing that part of the 

 shell to be much more convex than any other portion. Ribs some- 

 what prominent, the surface between them slightly concave and com- 

 pletely covered with numerous very small dots or raised punctations 

 of rather a regular figure. The lower edge of each rib is beaded like 

 the last, but the dots are smaller. The shell is considerably more 

 elongated than in preceding species, and the beaks are more pro- 

 minent and rather nearer the anterior extremity. The colour is 

 much lighter ; the ribs rather less prominent, and the punctations 

 on the intermediate spaces much smaller and a great deal more nu- 

 merous. 



Hab. Pool of rain-water at Malta, Rev. Mr. Hennah. Brit. Mus. 



Sp. 3. Estheria polita, Nobis. (PI. XI. f. 3, 3a, 3b, 3c.) 

 Carapace-valves obovate, resembling in form the shell of a Pisidium. 

 Anterior extremity somewhat broader than posterior, much more 

 convex and gaping. Beaks prominently elevated, and situated near 

 the anterior extremity. The shell is of a light yellowish horny co- 

 lour internally and externally, and of a fine glossy polished appear- 

 ance and finely pellucid. The ribs are numerous, about 27 in num- 

 ber, elevated, and smooth. The spaces between are slightly concave, 

 and are beautifully dotted with numerous small impressed punctations. 

 Hab. India, Captain Bogs. Brit. Mus. 



