87 
Hab. Fontainebleau. British Museum ; sent to Dr. Leach by 
M. Brongniart. 
Sp. 2. Limnapia Mavritiana. 
L. Mauritiana, Guérin, Mag. de Zool. Class 7. t. 21. f. 1-11, 
1837; Iconogr. Régn. Anim. Cuv. t. 33. f. 2. M. Edwards, Hist. 
Nat. Crust. iti. 363. No. 2. t. 35. f. 7-8. Burmeister, Organiz. of 
Trilobites, Ray edit. t. 6. f. 15. 
Carapace-valves of an oval shape, slightly pointed at the extre- 
mities ; antennules club-shaped, not crenulated on the upper edge, 
and considerably shorter than in preceding species, and the branches 
composed of only 9 joints in each; feet 18 pairs in number ; caudal 
lamellee shorter than in preceding species and more spine-shaped. 
Not having seen this species I am unable to describe the structure 
of the carapace. 
Had. Island of Mauritius, M. Desjardins. 
Genus Estuerta, Riippell. 
Carapace smaller in proportion to the size of the animal than in 
preceding genus, the animal nearly filling the entire cavity ; head 
large and somewhat projecting beyond the margins of the valves ; no 
pyriform organ; caudal segment large and terminating in four la- 
melle in form of strong curved hooks; small antennz linear or 
slightly tapering towards the apex ; jaws fleshy ; carapace of a trans- 
lucent horny or yellowish colour, of moderate thickness, and showing 
numerous strong concentric ribs; the surface between the ribs is 
generally strongly punctate or striated, presenting considerable va- 
riety in their sculpture, which affords good specific characters; the 
animals swim on their belly, and many males are found among them. 
A. Valves of carapace dotted or punctate on the surface. 
Sp. 1. Esruerra Gres. 
Syn. Daphnia gigas, Hermann, Mém. Aptérol. 134. t. 5. f. 4-5; 
t. 9. f. a, 1804. 
Cyzicus Bravaisii, Audouin, Aun. de la Soc. Entomol. vi. Bulletin, 
- 9, 1837. 
e Isaura Cycladoides, J oly, Ann. des Scien. Nat. 2nd ser. xviii. t. 7, 
t. 8, t. 9, f. 1-44, 1843. 
Estheria Cycladoides, Lucas, Explor. Scient. de l Alger. Crus- 
tacés, 81, 1845. 
Limnadia Hermanni, Koch, Deutsch. Crust. H. xxxv. t. 10. 
Monoculus lenticularis? Linneeus, Faun. Suec. 2051. No. 8; Syst. 
Nat. ed. 12th, 1059, No. 8. 
Carapace-valves of a rounded oval form, resembling considerably 
the shell of a Cyclas ; of a horny amber colour and translucid ; an- 
terior extremity rather broader than posterior ; both finely rounded ; 
beaks prominent, situated nearer the anterior extremity of the cara- 
pace, which is much more convex at that part than elsewhere ; the 
-two valves are marked with concentric striz or ribs, varying from 
20 to 26 in number. When viewed under the microscope, the 
