48 



1. subtruncata. 



Mactra subtruncata, Mont. — M. stultorum, 

 Pen7i. — M. deltoides, Lam. 

 Douglas ; Ramsay Bay. 



2. elliptica. 



Mactra elliptica, Brown. 



As I am not acquainted with any published de- 

 scription of this very distinct species, I give the cha- 

 racters — (a figure may be found in Captain Brown's 

 illustrations.) Shell transversely ovate, sub-triangular, 

 nearly equilateral, obsoletely striated transversely ; 

 margin prominent between the beaks and the angles ; 

 lateral teeth striated. Colour yellowish-white. 



Br. li ; L. f ; Thickness, f . 



In the collection of the Jardin des Plantes, are 

 specimens of a shell very near to, if not identical with 

 this species, labelled " Mactra semistriata." 



In deep water on the north coast ; not frequent. 



LXXI. Goodallia, Twr^.* 



1. triangularis. 



Mactra triangularis, Mont. — Goodallia trian- 

 gularis, Turt. — Mactroidea triangularis. 

 Brown. 

 Entangled in the byssi of Modioli, from deep water 

 off Douglas, but rare. 



2. minutissima. 



* The shells of this genus have been supposed by some British 

 conchologists to be the young of Astarte. I have in my collec- 

 tion the young of Astarte scotica, no larger than Goodallia trian- 

 gularis, yet presenting all the characters of the adult shell. 



