88 TERRESTRIAL AIR-BREATHING MOLLUSKS. 



Macrocyclis, Beck. 



Animal heliciform ; mantle posterior, covered with a shell ; eye-peduncles 



long, slender; foot narrow, twice as long as the diameter of the shell, tail 



j,.j iQ pointed, scarcely reaching behind the shell; res- 



f-^^^'SlL V piratory and anal orifices on the right of the 



^^^"V^^ mantle, under the peristome of the shell ; gen- 



" ' \_ ^r erative orifice behind the right eye-peduncle; 



.^^_ _ _.. ^^^^HB^"^ no distinct locomotive disk or caudal mucus pore. 



Animal of Macrocyclis eoncava. CimlvorOUS. 



Shell thin, widely umbilicated, depressed, striate or wrinkled, color uniform ; 

 whorls 4|-5, the last broad, depressed, moderately deflexed in front ; aperture 

 obliquely ovate ; peristome somewhat thickened or expanded, the margins 

 approximating, the basal shortly reflexed. 



A few species of this genus have been found in Chili and the West Indies. 

 It seems, however, to reach its greatest development in our Pacific Province. 



Jaw crescentic, ends sharply pointed, anterior surface striated ; cutting mar- 

 gin smooth, with a median projection. I have examined the jaw of M. Van- 

 couverensis (Fig. 11), sportetla, eoncava, Duranti, Voyana, 

 and in the West Indian species, M. Baudoni,^ Petit, and ^'^- ^^ - 



M. eiispira, Pfr.^ 



The general arrangement of the lingual membrane of , , _ . 



o o D ^ jaw^ of Macrocychs 



Macrocyclis is the same as I have described above for Vancouver ensis. 

 Glandina. 



There are 32 rows in one lingual examined of M. Vancouverensis. The rows 

 of teeth are arranged en chevron. Each row is divided by the median line into 

 two irregular crescents, the teeth rapidly increasing and curving in a back- 

 ward direction, and then gradually decreasing in size and curving forward. 

 (See my figures on PI. I.) In M. Vancouverensis the sixth tooth is the largest. 

 The teeth of Macrocyclis, as also of Glandina, are separated, not crowded, as 

 in the llelicea. The central tooth is seen with some difficulty by the micro- 

 scope. I am confident, however, that I have drawn it correctly for the various 

 species. In M. Vancouverensis (PL I. Fig. B) the base of attachment is small, 

 triangular, the apex pointed forward, the angles bluntly rounded, somewhat 

 incurved at base, and bears a delicate, simple, short, slender cutting point, 

 reaching from about its centre to near its base. This cutting point was not 

 figured by Morse, and, indeed, was observed by me only on a few of the cen- 

 tral teeth, and then with difficulty. In M. eoncava (PL I. Fig. C) the central 

 tooth has a larger base of attachment, the apex of the triangle is truncated 

 and incurved, the base is more incurved, the outer lower corners more ex- 

 panded and pointed, the cutting point more developed, with distinct lateral 



1 See Am. Joxam. Conch., VIL 175 ; Ann. Nat. Hist. N. Y., X. 305. 



2 See Proc. Ac. Nat. Sci. Phila. 1875, 247, PL XXI. Fig. 3. 



