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MAZATLAN UNIVALVES 
Orper PECTINIBRANCHIATA. 
SuBorpER ROSTRIFERA. 
Famity VANICORIDA. 
GENUS VANICORO, Quoy FF Gain. 
Vanikoro, Quoy & Gaim., Voy.& primA manu; (postea Sigaretus 
seu Velutina,)—Gray, Proc. Zool. Soc. 1847, p. 156, no. 256.— 
Hf. & A. Ad. Gren. vol. i. p. 374. 
Narica, #écl. in Sagr. Cub. Moll. 1836, teste Phil. Handb. 
Conch. p.184.—** M. Récl. has the intention to form a genus,” 
D Orb. Cuba, vol. ii. p. 39: genus constituted, 1844: teste 
Gray. 
Merria, Gray, Zool. Beech. Voy. 1839, p. 137, (anim. descr.) 
Leucotis, Swains. 1840, Treatise, p. 346. 
330. VANICORO CRYPTOPHILA, 2. S. 
V. t. parva, Sigaretoided, tenui, albida; nucleo anfr. 1. 
quorum primus planatus, alteri subturriti, tenuissime striati, 
decliviter sito ; anfr.normalibus uu. rapide augentibus,subplana- 
tis, irregulariter striulis spiralibus creberrimis et striis tncre- 
menti, interdum his, interdum illis superantibus, tenuissime 
cancellatis ; aperturé valde expansé, vix peripheriam penul- 
timam attingente ; labro elongato, labio recto ; wnbilico maximo ; 
peripheria angustiore. . 
This little creature resembles the Calyptreide in its seden- 
tary habits, feequenting the burrows of worms, &c. in Spondylus 
and Chama valves, where its flattened form and advanced Sip 
(in this respect resembling Trochita) allow it to live ina very 
narrow space. Many specimens were found in situ, but there 
was no trace of operculum. A minute shell of one whirl (found 
inside the mouth of another,) is perfectly formed, like a tumid 
Planorbis. Another, which was adhering over the umbilicus of 
an adult, is just preparing tc commence the normal portion, 
and is shaped like a Bithinia. Ii then lays iis spire sideways, - 
but not always at the same angle, and begins a flattened 
Sigaretoid growth. The sculpture is extremely variable, 
sometimes nearly evanescent. Most of the 85 specimens found 
were very small; the nuclear shell measures ‘02 by ‘016; a 
remarkably large specimen measures long. 15, lat. ‘17 by 15. 
