PLEUROTOMID^E. 1 5 9 



narrow, terminating in a rather short, truncated canal ; lip-sinus 

 near the suture. No opercultim. 



Foot dilated in front, and attenuated behind ; eyes placed on 

 peduncles connate with the tentacles, and at about the middle of 

 the latter, and exterior. Teeth hastiform (1-0-1). 



The animal of Mangilia is slow in its movements. It can 

 sustain itself at the surface of the water, shell downwards. The 

 oviposit consists of membranous hemispherical capsules, having 

 a central opening, ordinarily attached to the interior of old 

 bivalve shells. Each capsule contains from 200 to 300 eggs 

 (Jeffreys, Brit. Conch., iv). 



The great number of small species, inhabiting all portions of 

 the globe, which have been referred to Mangilia, may be conve- 

 niently divided into the following sections : 



Section MANGILIA (restricted). Shell longitudinall} 7 costulate ; 

 aperture narrow ; lip varicose ; sinus well marked ; canal short. 



Section CYTHARA, Schum., 1817 (not Klein, 1753 = Harpa. 

 Otocheilus, Gonr. ; Cytharella, Monteros ; Eucithara, Fischer, 

 1883). Shell Columbelliform, longitudinally costellated ; spire 

 short ; aperture narrow ; outer lip denticulated within ; colu- 

 mellar lip striated. 



Section CYTHAROPSIS, A. Adams, 1865 (not Citharopsis, Pease 

 = Columbellidse). Whorls of the spire cancellated ; colurnella 

 sillonated ; canal curved, elongated. 



Section GLYPHOSTOMA, Gabb, 1872. Shell fusiform ; columellar 

 lip plicated throughout ; outer lip thickened, plicate within ; sinus 

 profound ; canal long, somewhat bent. 



Founded on a West Indian tertiary fossil, but some living 

 species are referred to the group. 



Genus CLATHURELLA, Carpenter, 1857 (Defrancia, Millet, 



1826.) 



Apex mammillary ; sinus varicose, sutural ; columella tubercu- 

 lated posterior^, rugose in front ; canal slightly curved. Den- 

 tition, PI. 33, figs. 56, 57. Defrancia was preoccupied by Bronn 

 for a genus of Polyzoa ; but that is said to be a synonym of 

 Pelagia, Lamouroux ; so that perhaps it ought to be restored for 

 the mollusks. Clathurella appears to differ from Mangilia prin- 

 cipally in its more rounded whorls, and cancellated sculpture. 



