45 



» as a remarkable variety of the Unio Margaritifera, 



^"q- {Lin. 4^c.) and exhibited it as such three years ago to 



8Hi?3j the Royal Physical Society of Edinburgh. The col- 



•37?'-; lection and observations of Mr. Nicol have confirmed 



me in that opinion, he having in his cabinet all the 



gradations of form, from Unio elongata, Lamarck^ to 



the Unio Roissyi of Michaud, collected by him in 



the rivers of Scotland. Mr. Lea of Philadelphia, in 



his lately published synopsis of the Naiides, also 



places Unio Roissyi as a variety of U. Margaritifera. 



Michaud's specific characters are these : — 



" Unio testa oblonga, atra, rugosa, crassa, tumida, 

 undique hiante, anterius obtuse-angulata, posterius 

 latiore, superne arcuata ; intus carneo-coerulaso-mar- 

 garitaceti, viridi maculata ; natibus depressis, decor- 

 ticatis ; dente cardinali crasso, parvo, subacuto, laterali 

 subnullo."— (Mich. Comp. p. 112, pi. 16, f. 28.) 



In the Black river ; common near Kirk Braddan 

 Church. It was formerly much sought after by the 

 inhabitants for the sake of the pearls, which it not 

 unfrequently contains. 



Fam. Conchacea. 



LXIY. Cardium, Lin. 

 1. aculeatum, Lin. 



Test. jun. C. ciliare, Lin. 

 The animal is described by Risso. 

 Dead valves of this species are sometimes cast on 

 shore at the Point of Ayre ; but I have never taken 

 it alive on the Manx coast. 



