134 AMERICAN JOURNAL 



angle of the latter two broad, roundly-recurved processes are 

 extended posteriorly. The anterior apical angle of the septum 

 is extended a short distance in front of them and is somewhat 

 before the anterior point of its base. The muscles are stout and 

 well developed ; the neural insertion of the cardinals is about 

 the middle of the valve. The margin is sometimes slightly 

 flexuous. The measurements of three specimens are '44, '48 

 and -24 in. long ; -5, -52 and -32 wide ; by '16, '21 and '09 in. 

 in diameter. The apex of the neural valve is '09 in. above the 

 apex of the haemal valve in the largest specimen, and the width 

 of the foramen is '05 inches. 



This is the first described recent species, belonging to the true 

 type of Magas, with the reflected processes disunited, and does 

 not appear to have been noticed by European authors* under any 

 name. Since the opinion might be advanced that the reflected 

 processes had been broken apart, I would state that I have ex- 

 amined specimens still containing the brachia, and the complete 

 disunited ends of the processes might be readily seen with a 

 glass through the translucent animal matter. The brachia ap- 

 peared to be a simple loop without lateral lobes or central spiral 

 lobe. It is still possible, however, that in older specimens the 

 loop may be completed, bringing the species into the next sec- 

 tion. 



Subgenus Magasella, Dall. 



Shell with the reflected portions of the apophyses united, 

 forming a loop. 



This comprises most of the recent species of Magas. 



Fig. 16. 



Fig. 16 a, b. Magasella Evansii, Dav., haemal valve and profile; *, septum. 



Type. Magasella Evansii, Dav., fig. 16 a, b. 



Terehratella Evansii, Dav., Proc. Zool. Soc. 1852, p. 77, pi. 



xiv, fig. 7—9. An. Nat. Hist. 1852, p. 368, n. 26. 



Woodw., Rec. and Foss. sh. p. 217, fig. 116. 

 Magas Uvansii, Gray, B. M. Cat. p. 99, fig. 11 and 12. 

 Magas Valenciennesii, Rve., Conch. Icon. pi. viii, fig. 31, a, 



b, c. Journ. de Conchyl. 1861, p. 130. 



* Except Suess, 1. c. 



