1868.] MR. R. B. SHARPE ON THE GENUS CEYX. 587 



which have two spines on the anterior vim of the thorax, are marine, 

 while tliose of the genus Pa/cemoti, with the two spines of the thorax 

 placed one behind the other, are exclusively freshwater forms. This 

 is decidedly wrong, according to my own observations in the Philip- 

 pines. There are genuine species of Palceinon and Leander in the 

 sea as well as in rivers and lakes. Philippi's genus Bithijnis, with 

 only 07ie spine on the anterior rim, may therefore be considered 

 a third subgenus of Palcemon. The synonymy of this species is 

 therefore as follows : — 



Paleemon gaudichauilii, Olivier. 

 Palcemon cocmentarius, Poeppig. 

 Bithynis longimann, Philippi. 

 Macrobrachium africanum, Spence Bate. 



I am very glad that I need not change the latter name, which I 

 should be obliged to do if it really were a new species. Mr. Spence 

 Bate seems to be of opinion that the Tambo River is in Africa, 

 whereas it is really on the west coast of South America, near Islay in 

 Peru. The original specimens were collected there by Mr. Whitely. 



When Mr. Spence Bate expresses the ojiinion that all the four 

 species of his supposed new genus have descended from one single 

 primitive form, the reasons which he alleges in favour of this view 

 are not convincing. My own observations in the Philippines make 

 me rather doubtful of the alleged fact that only one particular and 

 no other Palsemonide inhabits each river and lake. 



The new genus of Mr. Spence Bate must therefore be suppressed, 

 and also three of his supposed new species. It is not a new fact that 

 these large species of Palcemon can be eaten, nor that they live in 

 fresh water. The older naturalists, as Sloane, Parra, Leach, Poeppig, 

 and Philippi, knew it long ago, as may be seen from their writings. 



7. On tlie Geuus Ceyx. 

 By R. B. Sharpe. 



It seems necessary to say a few words on this genus, as consider- 

 able confusion still exists with regard to the correct determination 

 of some of the species ; and I am further anxious to set right a point 

 in the synonymy of two of them, by which I myself, in my ' Mono- 

 graph of the Alcedinidce,' as well as other ornithologists, have been 

 led into error. 



The genus Ceyx was established in 1801, by Lacepede, and the 

 species uicluded in it have only three toes. The birds seem prin- 

 cipally insectivorous, in contrast to the members of the three-toed 

 genus Alcyone, the species of which are closely allied to true Alcedo, 

 and are almost wholly piscivorous. All the members of the genus 

 Ceyx seem occasionally to feed on fish, but are not generally found 

 in the neighbourhood of streams. In their general habits they are 

 allied to the African Isjudina. 



The genus Ceyx may be divided into two natural sections, viz. 



