376 Mr. L. A. Borradaile — A Revision 



Estlteria gihoni seen in a glass of clear water is a beautiful 

 object ; it swims upright, with the finely-sculptured valves 

 of its carapace slightly open, so as to allow part of its bright 

 red body to be seen. The branchial feet are in constant 

 motion except when the animal, after a lengthened swim, 

 goes to the lottom and either burrows in the mud or falls 

 over on its side on the surface, when the branchiae move very 

 feebly. When fully grown the male (which is somewhat 

 larger than the female) measures 5 lines in its longest diameter. 

 For the fust month of life they seem to be continually active, 

 but w hen adult are often in repose, sometimes for many hours 

 together. When copulating the female is seized by the pre- 

 hensile feet and held firmly by the strong hooks with which 

 they are armed, and in this attitude, which looks as if she 

 were carried in the male's mouth (almost like a dog with a 

 rat), she is hurried along round and round the jar, the male 

 retaining his hold for hours, and occasionally expanding the 

 valves of the carapace in his flight. 



The same evolution as above described in the case of 

 Branchipus, of throwing up nnul and sweeping it with the 

 branchiae towards the month, while turned on its back, is 

 equally true of Estheria. I have kept the Esther ice, 

 J hnihnice, and Cypridce for four months, but Branchipus, 

 DiaptomuSj and Cyclops are more short-lived. 



XLIII. — A Revision of the Pontoniidse. By L. A. BORRA- 

 daile, M.A., Lecturer in Natural Sciences at Selwyn 

 College, Cambridge. 



The first of the species of the Pontoniida? was described by 

 Foiskal in the year 1775, when he gave the name of Cancer 

 custus to a small prawn found living in the mantle-chamber 

 of a bivalve mollusk. In 18^0, after certain wanderings, 

 this species, under the name of P. tyrrhena (Risso), found a 

 home in the genus Pontonia, established for it by Latreille ; 

 and by 1837, the date of publication of H. Milne-Edwards's 

 ' Crustaee'es,' the number of species of Pontonia had risen 

 to four. A closely allied genus, Conchodytes, was described 

 by Peters in 1851. 



After the appearance of ]\iilne-Edwards's work no step of 

 great importance in the history of the family was taken till 

 Dana, in 1852, reporting on the Crustacea of the United 

 {States Exploring Expedition, separated from Pontonia groups 



