1880.J NATURAL SCIENCKS OF PHILADELPHIA. 55 



part of the sucking-crop of 5.5 mm.), and a breadth of 4.75 mm. ; 

 the sheath of the radula projecting about 1.3 mm. backwards and 

 downwards. The lip-disk large, clothed with a thick yellow cuticula ; 

 the true mouth forming a narrow vertical slit. The cap-shaped suck- 

 ing-crop almost exactly as in Ac. pilosa, but more conical and with- 

 out external signs of duplication : on the inside clothed with a yellow- 

 ish cuticula, opening into the buccal cavity through a wide slit. The 

 tongue rather broad ; on the fine reddish-yellow colored radula seven- 

 teen rows of teeth, also on the point of the tongue were traces of six 

 entirely vanished rows ; the two first rows very incomplete, reduced to 

 some external plates. Further backwards were seen forty-two devel- 

 oped and three younger rows, or, all in all, the animal presented sixty- 

 two rows of teeth. The most external plate of each row is quite 

 colorless, the next two or three pale yellowish, the following all of 

 horny-yellow color ; the rhachis colorless. The length of the most 

 external plate about 0.0.35 mm., of the next about 0.05 mm., of the 

 following 0.07 mm. ; the length of the second large plate about 0.2 

 mm., of the first 0.022 mm. ; the breadth of the rhachis about 0.22 

 mm. The rhachis thickened between the rows and forming arched 

 elevations between them (PI. VI, fig. la, 3 ; PI. VIII, fig. la). The 

 first two plates rather large (PI. VI, fig. Ibb, cc, 4-6; PI. VIII, fig. 

 16, c) ; with a short strong hook and a stout denticle at each side of 

 it, the outer denticle broader ; the hook of the second plate somewhat 

 larger than that of the first ; sometimes a slight crenulation on the 

 outer margin of the first plate (fig. 5). All the following ten or eleven 

 plates (PI. VI, fig. 2e, /; PI. VIII, fig. 2a, b) of the same type, by 

 degrees decreasing in size, consisting of a quadrilateral basal part, 

 from which (PI. VI, fig. 7-13), in most of them, rises a strong, short, 

 broad hook ; the two or three outmost plates (PI, VI, fig. 2/; PI. VIII, 

 fig. 2) formed of the basal part alone ; the rest with the hook gradu- 

 ally more developed 



The salivary glands yellowish-white, flattened, ribbon-shaped, of 

 about 10.5 mm. in length, reaching to the cardia, where they 

 are agglutinated one to another ; the breadth in the foremost part 

 about 0.75 mm , in the middle 1.5 mm., the posterior part again some- 

 what narrower ; the duct of the gland rather short. 



The oesophagus rather wide, about 13.0 mm. long, the inside with 

 rather strong longitudinal folds ; it opens into the stomach, which lies 

 free in a cleft on the upper side of the liver. This organ (PI. VI, fig. 

 17a) is of oval form, of about (3.5 ram. largest diameter; the inside 



