76 The Molluscau Family Plauorbidae 



1929. Armiger Odhxer, Die Mollusk. Fauna Takern, p. 22. Type Armiger crista 



(Linn.). As genus on anatomical grounds. 

 1931. Artniger, Germ.^in, Moll. terr. fluv. de France, II, j). 540. Type Plonorbis crista 



(Linn.). As subgenus of Planorbis. 

 1931. Armiger Thiele, Handbuch, IV, Teil 2, p. 481. Type Anisus (Armiger) crista 



(Linn.). As subgenus under Anisus. 

 1935. Armiger A. Soos, Allat. Kozleni., XXXII, p. 30. As subgenus of Gyraulus. No 



type indicated. 



Shell (i)late 76, fig. 6). Ultradextral, small, with few rapidly increasing, 

 costate whorls, the costae usually projecting at the periphery. The general 

 form is like that of Gyraulus. 



Animal. External form like that of Gyraulus. 



ANATOMICAL CHARACTERISTICS 

 PLATE 18 



GENITALIA. Male Organs (plate 18, fig. 7) . Seminal vesicle (SV) with 

 very few large glands or diverticula. Sperm duct 1.5 mm. long, bent upon 

 itself in a loop posterior to the prostate. Prostate 0.5 mm. long, consisting 

 of thirteen long, cylindrical diverticula placed on a separate prostate duct. 

 The free portion of the prostate duct is very short. Vas deferens a long 

 (1 mm.), small duct. 



Penial complex (fig. 7) with a vergic sac one and one-half times as long 

 as the preputium. The vergic sac is enlarged at the end w^here the vas 

 deferens enters it as an enlarged tube. There is one retractor muscle (RM). 

 The preputium is of larger diameter than the greater part of the length of 

 the vergic sac. 



Internally (fig. 9) the j^enial complex is formed like that of Gyraulus. 

 There are two }ulasters, a dependent papilla (D), and also a muscular ring 

 or diaphragm (not shown in figure). The verge (V) is elongated, cylin- 

 drical, tapering gradually to the end, which does not bear a horny stylet, 

 as in Gyraulus, but a small, pointed fleshy papilla (fig. 10, PA, fig. il, PA). 

 The opening of the sperm canal is just above this papilla at the end of 

 the verge, in the center and not at the side as in Gyraulus (figs. 10, 11, SC). 



Female Organs, The spermatheca (S) is long and pyriform in shape, 

 taj^ering gradually to the short, wide vagina (VG) , the duct being very 

 short. The uterus (U) and nidamental gland are wide, the uterus short and 

 the gland rather long. The oviduct (OD) is short and greatly swollen below 

 the junction with the sperm duct to form the ovisperm duct. The albumen 

 gland (fig. 8) is large (1 mm.), elongated and composed of large gland 

 cells. It is joined to the large, bulbous carrefour (CF) by a long, very fine 

 duct (DA). The carrefour connects with the oviduct. The intestine ex- 

 tends the whole length of the albumen gland which covers the greater jmrt 

 of the intestine. The space occupied by this organ is shown in the 

 figure (AL). 



Hermaphrodite Organs. The ovotestis (OT) consists of many club- 

 shaped diverticula placed in a double row. The ovisperm duct (SO) is 

 twice as long between the oviduct and the seminal vesicle as between that 

 organ and the ovotestis. 



No figure of the whole genitalia of Armiger was available before the 

 publication of A. Soos's paper in 1935. His figure (1935, p. 28) differs in 

 several respects from the ones here presented. The prostate has nine 



