288 The Natiiralist of Cumbrac. 



of Pecten $eptcmradiatus> that I would give him a 

 penny apiece for them. He asked how many I would 

 take. To give him a wide berth, I said I would take 

 one pound's worth. A few days after he wrote me 

 that he had procured eight hundred. He had found 

 out that in some places of the loch, when the herring- 

 nets got down to lie on the ground, they came up 

 with scores of this shell attached to them, and from 

 this he had learned how to secure a good haul. It is 

 probable the explanation is that the shells lie with 

 the valves gaping, and when the cords of the net get 

 between them the valves close upon the meshes and 

 hold fast. It is not unlikely that Echinus neglectus 

 may not be as scarce as it seems to be. As Echinus 

 sphaera is so variable, both in colour and form and 

 in the character of its spines, Echinus neglectus would 

 readily be passed over for Echinus sphaera, except 

 by those who are specially engaged in that particular 

 branch." 



To Robertson's experience with his rare Pecten 

 there is an amusing parallel in an anecdote which 

 Norman relates in the fourth volume of Bowerbank's 

 " British Spongiadse " : 



" When Dr. Bowerbank first commenced the study 

 of British sponges, the Tcthya, etc., were considered 

 extremely rare. Desirous of possessing these fine 

 species, he wrote to the fishermen's agent at the 

 Out Skerries, and said he would give sixpence each 

 for all that he could procure. No doubt our old 

 friend thought the offer an uncommonly safe one ; 

 but in a short time a huge keg of sponges came 

 (300 Tethyciy see ii. p. 84, among them !) and a nice 



