BRACHIOPODA. 97 



Genus IPIIIDEA, Billings. 1872. 



PLATE IV, FIGS. G-9. 



1872. Ipkidea, Billings. Canadian Naturalist, New Series, voL vi, p. 477. 



" 1874. Iphidea, Billings. Palseozoic Fossils, vol. ii, pt. i, p. 76. 



1876. Iphidea, Linnaes.wn. Brachiopoda of the Paradoxide.s Bed.s of Sweden, p. 25. 



1886. Iphidea, Walcott. Bulletin No. 30, U. S. Geolo-^ical Survey, p. 100. 



Diagnosis. " Of this genus we have no specimens showing the internal 

 structure, but the external characters seem sufficient to separtite it from any 

 described generic group. The ventral ? valve of /. bella is conical, strongly 

 elevated at the beak, hinge-line nearly straight, posterior angles narrowly 

 rounded, sides and front nearly unilbrmly rounded, forming rather more than 

 a semicircle. Posterior side with a large false area anda convex pseudo-delt- 

 idium, the Avidth of which at the hinge-line is nearly one-third tiie whole 

 width of the shell. The dorsal valve is semicircular, moderately convex, most 

 elevated at the beak The hinge-line appears to be straight. * * * 

 The surface is covered with fine concentric striae, which in the ventral valve 

 are continued around on the area."* 



Type, Iphidea bella. 



The foregoing diagnosis is derived from the original description of the type- 

 species, Iphidea bella.' After the lapse of eighteen years since the date of its 

 publication little has been contributed to our knowledge and no facts of 

 es.sential importance bearing upon the external characters ofthe.se shells; 

 of the interior we still know nothing. In 1873, Mr. Meek described the species 

 Iphidea (J?) scidptilis,f from the Gallatin River, Montana, but as the hinge-line 

 and subapical area of the shell have not been observed, and on account of its 

 apparent specific identity with the Kutorgina minutissima, Hall and Whitfield, it 

 has been referred provisionally to the genus Kutorgina by Mr. Walcott, and 

 the latter species reduced to a synonym. i Dr. Lin.varssox described the species 

 I. ornatella, from the Paradoxides beds,§ giving good figures of the exterior of 



* Billings. Canadian Naturalist, 1872, loe. cit. 



i Pieliminary Pal^ontol. Kept. : Sixth Ann. Rept. U. S. Geolo-fieal Survey T.m r., [p. 479. 

 t Palaeontolog-y Eureka District, p. 20. 



§ Brachiopoda of the Paradoxides Beds of Sweden : Bilian^' till K. Svenska V.-t Akad. handlingar, Bn.l. 

 3, No. 12, p. 25, pi. iii, figs. 42, 43. 



