280 



NEOBELISCUS. 



Genus NEOBELISCUS Pilsbry, 1896. 



Neobeliscus PILS., Nautilus, x, p. 46 (August, 1896). PILS- 

 BRY and VANATTA, Proc. A. N. S. Phila., 1899, p. 366 (ana1> 

 omy) . Obeliscus, Columna and Bulimus sp. of authors. 



Shell imperforate, large and solid, turrite, slowly tapering 

 to a large conic summit. Aperture irregularly ovate, the 

 outer lip acute and simple, columella vertical, its edge nar- 

 rowly reflexed and adnate. Viviparous, the embryonic shell 

 very large at birth, about one-fourth the length of the adult 

 shell and exceeding one-third its diameter, with half the adult 

 number of whorls, being composed of 5y 2 , the first 1% whorls 

 smooth, forming a convexly-conic, obtuse summit, the rest 

 densely and very finely striate; columella slightly concave, 

 not in the least truncate. Type N. calcarius. 



Distribution: Southeastern Brazil. 



Neobeliscus was no doubt derived from Obeliscus, from 

 which it differs in the great size of the embryos, which have a 

 bluntly conic instead of hemispherical summit. Only two are 

 contained in the uterus at one time, while in Obeliscus they 

 are numerous and small. The columella of the embryonic 

 shell is not truncate, resembling typical Obeliscus in this re- 

 spect, and unlike Protobeliscus, Rhodea and Stenogyra, which 

 retain the earlier feature of a truncate columella. The foot 

 is very short and broad, squarely truncated behind ; with no 

 appearance of grooves or specialized granulation above the 

 margins; sole undivided. 



Genitalia (pi. 45, fig. 5) without accessory organs, the 

 atrium short. Male system with a long, club-shaped penis 

 with strongly folded internal walls, and terminal retractor 

 muscle and vas deferens. Talon (fig. 4, t.) large, consisting 

 of a swollen distal portion on a narrow, devious duct of sim- 

 ilar length. The attached portion of the sperm-duct is com- 

 posed of a dense mass of radiating tubules or caeca. Female 

 system with the vagina rather short, spermatheca oblong, 

 borne on a duct of about double its own length, and remote 

 from the heart. Free oviduct as long as the spermatheca 

 duct. Uterus with thin walls, enormously distended when 



