15S PORPIIYROlSArilK. 



stome blunt, white or flesh-colored, expanded, becoming subreflexed 

 below ; columella vertical, straight or convex, white ; parietal callus 

 white. 



Alt. 73, diam. 39, longest axis of aperture 43 mill. 



Alt. 62, diam. 39, longest axis of aperture 39 mill. 



Colombia: La Ceja, Rio Negro (type locality) and mountains near 

 Fresno, between Salamina (tnd Sunta Ana (Bid.). 



/Mimas iris PFK., P. Z. S. 1852, p. 136; Conchyl. Cab. p. 244, 

 pi. 65, f. 4, 5 ; Monogr. iii, p. 313 ; iv, 376 ; vi, 22 Don UN, Jahrb. 

 d. D. Malak. Ges. ii, 1875, p. 298 BnHinug u-aUisiunits MOUSSON, 

 Malak. Blatter xxi, 1873, p. 9 __ PFK., Novit. Conch, iv, p. 135, pi. 

 130, f. 7, 8 ; Monogr. viii, pp. 15, 604. Kalinins (ftonts)fris H. & A. 

 AD., Gen. Kec. Moll, ii, p. 148. Porphyrobaphe iris Pfr., von MAR- 

 TKNS, Conchol. Mittheil., p. 174, pi. 35, f. 3 (apex). 



Similar to P. irrorafus and yrpri//ei in sculpture, but distinguished 

 by its Imsal keel. Dohrn has already discussed this species at some 

 length, the specimens I have seen supporting his opinion of the ex- 

 traordinarily wide swing of variation among individuals. 



Pl'eifl'er's original specimen was rather small, length 64 mill., with 

 the keel very near the columella, and the base, thcrelore, only slightly 

 distorted (tigs. 28,29). Mousson's ical/isiani/s (tigs. 31, 32) was 

 based upon a more strongly keeled shell, with very convex hody- 

 wliorl and brown-streaked coloring. The type measured t'-2 mill. 

 long ; one before me agrees exactly in color, form and size, see sec- 

 ond line of measurements above. A more aberrant, but in no way 

 pathologic individual, is shown in fig. 30. 



Dohrn gives the following extremes of size : 



Alt. <S7, diam. 41, length of aperture 48 mill.; thick and calcar- 



Alt. .".2-59, diam. 26-27, length of aperture 32-3-1 mill.; thin, 

 translucent. 



i- <>r P. DKNMM.NI. 



P. DENNISONI (Reeve). PI. 48, figs. I-", M, 15, H;. 

 Shell imperfi.ratc, ovate-acuminate, rather thin, subgranulated by 



liglit growtli stria- ami somewhat undulating close Spiral stria-, but 

 little shilling. Dull greenish but!', encircled with sonic pale hinds, 

 marked with sparse l>]acki-li streak.- and >tre\vn with purple-brown 

 Spire conic, the apex whitish, rather c,htu-i' ; suture impressed ; 



