CRUSTACEA OF NORTHUMBERLAND AND DURHAM 335 



The specific distinction between the two is certainly very 

 slight, but apparently constant. 



My discovery and re-discovery of this species I look upon 

 as one of the most curious and remarkable experiences in my 

 life as a naturalist. One afternoon, June 22nd, 1864, I 

 brought home a gathering made in a pond at Lambton 

 Park. Examination proved it in the main to consist of 

 Daphnia pulex ; but there floated across the field of the 

 microscope the post-abdomen of a Lynceid which I at once 

 recognised from its peculiar spination as something new to 

 me; but it flashed across me that I had seen somewhere a 

 figure like it. Taking down a MS. book from my library I 

 found in it a tracing made at the Brit. Museum Library of 

 Fischer's 'figure oi Lynceus acanthocercoides. That this species 

 described from Moscow should be here before me in that frag- 

 ment of a post-abdomen was of course of the highest interest. 

 The whole gathering was therefore passed drop by drop under 

 review in the microscope, and the remainder of the slough or 

 cast skin of the specimen to which the post-abdomen belonged 

 was met with, but no other specimen; and Moscow was its 

 only known home. 



Twenty years passed by. I had three or four times brought 

 home gatherings from the Lambton Pond, but the phantom 

 Leydigia had not shown itself again either to myself or, as far 

 as Lam aware, to any other British naturalist. Some young 

 friends were coming to me in the evening, and I required 

 living material to show them under the microscope. At the 

 breakfast table I told a nephew who was staying with me the 

 foregoing story, and said we would in the afternoon go to the 

 said pond to get what I required, and perhaps Leydigia might 

 be found. I went into my library and began to examine a 

 gathering I made ten days before at Seaton Carew, and there 

 was Leydigia \ I called up my nephew and remarked how 

 curious it was that it should thus have turned up just after I 

 had been talking about it. In the afternoon we went to the 

 old habitat in Lambton Park, and there again was Leydigia. 

 From two different localities in the same day ! 



H 



